Histology complete exam revision

Female Reproductive system

Female Genital tract: Ovaries Fallopian tubes (oviducts) Uterus Cervix Vagina Vulva Breast

Taste buds

-Onion-shaped structures -Contain 50 - 100 cells -Located on the basal lamina, microvilli are in contact with the surface through taste pores. -Undifferentiated basal cells are the germinal cells. Drawing showing taste bud structure . . . . . . .

Testes

Has 2 functions - reproductive / hormonal. Surrounded by thick capsule of connective tissue - tunica albuginea. Forms fibrous septae dividing the testis into lobules. Lobules consist of seminiferous tubules, Leydig cells, vessels and nerves. Labeled diagram showing testis . . . . . . . . . TA - Tunica Albuginea: The tunica albuginea ~ thickened region in its centerline = mediastinum testis. RT - Rete Testis: Through this (mediastinum testis) run tortuous channels lined with a low cuboidal epithelium = the rete testis. E - Epididymis Seminiferous tubules discharge their spermatozoa into these channels, which conduct them to the 7-15 efferent ducts. Efferent ducts are larger than the channels through the mediastinum, and collectively lead into a long, extremely coiled single duct, the ductus epididymis. -> This duct fills the epididymis.

Exam revision: Skin

Has four major functions: Protection: against UV, mechanical and chemical insults, micro-organisms and dehydration. Sensation: touch, pressure, pain and temperature. Thermoregulation: Hair and deep fatty tissue Metabolic functions: Triglycerides (fat) stored within deep tissue, Vitamin D is synthesised in this organ.

Female reproductive continued

Chorionic villi in the vicinity of the uterine wall. Surface of syncytiotrophoblast surrounding a core of mesenchyme containing foetal blood vessels. Foetal blood vessels visible only in largest villi. Villi vastly increase the surface area available for material interchange with maternal blood. Decidual cells are large cuboidal cells derived from endometrial stroma

Example questions

Describe the structural differences between the arterial and the venous systems. Describe the microanatomical structure of the heart. Draw a diagram of a medium sized artery indicating the relative positions of tunica intima, tunica media and tunica adventitia.

Myometrium

thick muscle layer with criss-cross fibres. Enlarges greatly during pregnancy for expulsion of fetus. Histology of Myometrium Bundles of smooth muscle in poorly demarcated layers Fibres oriented transversely, longitudinally and obliquely.

Four basic tissues

Epithelial / Connective / Muscular / Nervous

Larynx

Labeled Diagram showing Larynx: . . . . . . . . . . . .

Intramembranous ossification

- Direct replacement of mesenchyme - Membrane bones • Vault of skull • Mandible, maxilla Occurs within 'membranes' of condensed, primitive mesenchymal tissue. Mesenchymal cells differentiate into osteoblasts which secrete osteoid at multiple centres of ossification. Collagen fibres are randomly arranged in interlacing bundles. (hence woven bone) Woven bone gradually converted by progressive remodelling into lamellar bone.

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- Due to the fact that cartilage does not have blood vessels, it might produce inhibitors of capillary formation. Cartilage inhibits tumour growth when tumour and cartilage are implanted together.

Draw a diagram of the epidermis indicating the relative positions of the stratum corneum, stratum granulosum, stratum spinosum and startum basale Name three other cell types that are present in the epidermis (other than keratinocytes).

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Table showing Part of GI, type of epithelium, main cell types of epithelium, and other distinctive features.

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Histology of the Breast

15-25 independent glandular units = breast lobes. Arranged radially within fat. Each is a complex branching tubulo-acinar gland draining into a lactiferous duct. Each lobe of the breast contains numerous terminal duct-lobular units TDLU open into main duct TDLU consist of the terminal duct and a cluster of glands or acini which form the lobule Each TDLU lined by dual layer of epithelial and myoepithelial cells. Nipples Each duct has a slight dilation called lactiferous sinus just before opening into nipple. Each duct opens into the nipple independently.

Seminal Vesicle

2 highly tortuous tubes circa 15cm in length Folded mucosa with pseudostratified columnar epithelium. Produces a nutrient rich fluid for survival and motility of spermatozoa (up to 85% of total volume of seminal fluid). Epithelium is testosterone dependent.

Teeth and associated structures

2 major segments - Crown, project into buccal cavity. Root - embedded in the jaw. Enamel: It is the hardest component of the human body. It is derived from ectoderm whereas other parts of the tooth derive from mesoderm. Does not contain collagen. Contains: amelogenins and enamelins (ECM proteins). Enamel matrix is secreted by ameloblasts. Dentine: Calcified tissue in the form of hydroxyapatite. Harder than bone (more Ca) Composed mainly of type I collagen, glycosaminoglycans, phosphoproteins, phospholipids, hydroxyapatite crystals (Ca). Odontoblasts secrete organic material of the dentine. Dentine is sensitive to stimuli and contains a few unmyelinated nerve fibres. Picture showing teeth structure layers . . . . . . . . .

Penis

3 cylindric masses of erectile tissue plus urethra. Surrounded by skin. 2 of these cylinders are dorsal- corpora cavernosa . 1 ventral cylinder- corpus spongiosum ~ surrounds urethra.

Bone composition

30% organic- 90% type I collagen- 10% Proteoglycan - osteoid 70% inorganic- Calcium + phosphate- hydroxyapatite Active osteoblasts secrete osteoid collagen + matrix vesicles. Matrix vesicles are focus for deposition of hydroxyapatite crystals. Confluent mineralisation of osteoid collagen and supporting glycosaminoglycan. Vesicles rich in phosphatases ~ leads to accumulation of phosphate ions with eventual production of hydroxyapatite. Drawing showing the layers, clearly labeled. . . . . . . . .

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400,000 eggs at birth. Released at monthly intervals throughout reproductive life. (ovulation) Sequential cyclical changes occur in the uterine lining to prepare for pregnancy. Ovarian and uterine events are controlled by hypothalamic, pituitary and ovarian hormones whose levels are regulated mutually by feedback mechanisms. GnRH, FSH, LH, oestrogen, progesterone Cyclical changes halt if pregnancy occurs and resume when lactation finishes Diagram of Ovary . . . . . . . . . . . .

Follicle development / structure

400,000 of these primordial follicles are present at birth. (primary oocytes) During every ovarian cycle (i.e. each month) up to 20 primordial follicles are activated only one reaches full maturity and undergoes ovulation, the remainder degenerate i.e. undergo atresia. Total antral follicle count decreases with increasing maternal age and correlates with a reduction in fertility. Dominant (ovulatory) antral follicles are classified as those with a diameter equal to or greater than 6 mm. Challenger follicle (i.e.those seeking dominance) numbers peak at mid-follicular phase. The oocyte has increased substantially in cytoplasmic and nuclear size. Surrounding the oocyte is the specialised E.C. matrix, the zona pellucida. (pink layer) Surrounding the zona pellucida is a double layer of granulosa cells. Surrounding the granulosa cells are the developing thecal layers (flattened cells). Diagram of mature follicle . . . . . . . Secondary follicle - within zona granulosa have fluid-filled space = follicular antrum. Oocyte reached full size, eccentrically located in cumulus oophorus. Theca interna - (rounded cells) and theca externa (flattened cells) Membrana granulosa cells sit on the follicular basal lamina and line the antrum as a stratified epithelium. Following ovulation, these granulosa cells contribute to the corpus luteum. Cumulus oophorus is a column of granulosa cells that attaches the oocyte to the follicle wall. At ovulation, this column of cells is broken or separates to release the oocyte from its follicle attachment. Corona radiata ~ granulosa cells that directly surround the oocyte; released along with it at ovulation. Theca Interna (Greek, thek = box) Ovarian follicle endocrine cells forming the inner layer of the theca folliculi surrounding the developing follicle. Respond to lutenising hormone (LH) synthesising and secreting androgens (androstendione) transported to glomerulosa cells which process initially into testosterone and then by aromatase into oestrogen (oestradiol). Theca cells do not begin hormonal functions until puberty. Theca Externa The ovarian follicle stromal cells forming the outer layer of the theca folliculi surrounding the developing follicle within the ovary. Consisting of connective tissue cells, smooth muscle and collagen fibres. At ovulation the secondary oocyte is released, along with corona radiata (CR) into peritoneal cavity near the mouth of the Fallopian tube

Seminiferous Tubules

800-1600 with an aggregate length of around 600 metres. LINED BY - Stratified complex germinative epithelium 2 types of cells - Sertoli cells (have a characteristic dark nucleolus) / Spermatogenic (germ) cells. These cells reproduce several times and finally form spermatozoa, through a process called spermatogenesis.

Haversian Canal / System

A characteristic feature of adult compact bone is the presence of central Haversian canals, each about 22-110 μm in diameter, which run longitudinally within the substance of the bone and contain the blood vessels, which nourish the osteocytes. Central canals are surrounded by 4 to 20 successive layers of bone known as the concentric lamellae, each of which is 3 to 7 μm thick. A central canal and its associated concentric lamellae constitute a unit of bone structure called a Haversian system or osteone. Diagram of an Osteon / Haversian sys . . . . . . . . The osteocytes lie in lacunae - usually situated between lamellae. The lacunae are connected with each other and with Haversian canals by means of delicate canaliculi, which allow passage of nutrient substances from the bloodstream to the osteocytes.  Central canals are connected with one another, with the marrow cavity, and with the periosteal surface of the bone by perforating canals (nutrient canals; Volkmann's canals), which run obliquely or perpendicularly to the long axis of the bone. They can be distinguished from central canals in sections by their direction and by the fact that they appear to pass through lamellae rather than being surrounded by them.

Tongue

A mass of striated muscle. Covered by a mucous membrane with a variable structure. Dorsal surface is irregular and is covered by numerous papillae. Posterior 1/3 is separated from the anterior 2/3 by a V shaped boundary. The posterior portion mainly contains small lymphoid aggregates Filiform papillae: on the entire surface of the tongue, contain no taste buds. Fungiform papillae: interspersed among the filiform papillae and contain taste buds. Foliate papillae: not well developed in humans. Circumvallate papillae: largest and least common, encircled by a deep cleft, associated with serous (von Ebner's glands) glands which open into base of cleft, facilitating taste reception. Secrete lipase - dissolves food constituents and facilitates taste reception. Contains taste buds on their sides.

Lymph vascular system

A network of drainage vessels for returning excess extravascular fluid (lymph) from extracellular spaces to the blood. Transport lymph to the lymph nodes for immunological screening. The system has no pump, but most of the lymphatics have intrinsic pumping system effected by contractile smooth muscle fibres in the wall. Back-flow prevention is present due to valve system. Lymphatic vessels are found in all tissues except, the CNS, bone, cartilage, teeth, cornea and placenta.

Large intestine

About 1.5m long. Absorbs water and electrolytes from the approximate 1.5L of chyme passing through the ileocecal valve daily. Absorbs vitamins created by colonic bacteria, such as Vit K, Vit B12, thiamine and riboflavin. It also compacts faeces, and stores faecal matter in the rectum until it can be discharged via the anus in defaecation. Colon: Recovery of H2O, peristalsis of faecal material. Thick Muscular wall Absorptive cells and mucus-secreting cells. Commensal bacteria.

Endothelial cells

Act as a permeability barrier. Synthesise basement membrane, and secrete molecules which minimise pathological thrombus formation. (thrombomodulin, prostacyclin) Also secrete vasoactive factors controlling blood flow. e.g. nitrous oxide, prostacyclin and vasoactive peptides. Produce some growth factors. (e.g. fibroblast, growth factor, platelet-derived growth factor, blood cell colony stimulating factor)

Adipose tissue

Adipocytes are cells adapted for the storage of fat. May be found in isolation or clumps, or make up the bulk of the tissue as in adipose tissue. Generally has a rich blood supply as important for releasing energy. Hormones and the nervous system, diet and energy expenditure will all influence the fat metabolism of adipocytes. Adipocytes also are responsible for releasing several proteins = adipocytokinesis. e.g. leptin, tumour necrosis factor alpha, which regulate body mass and influence general metabolism. White adipose tissue 20% of body weight in normal male adults 25% females. Distributed throughout the body especially deep in the dermis. Thermal insulator and cushion against mechanical shock in sites like the kidney. Pale staining as it is occupied by lipid, leaving thin rim of cytoplasm and cell membrane. Adipocyte nucleus is squashed to one side. Adipocytes have receptors insulin, cortisol, growth hormone and noradrenaline. Brown adipose: Highly specialised, found in newborn mammals. Important role in temperature regulation. Adult humans have very little brown adipose tissue. Arranged in lobules separated by fibrous septae which convey blood vessels and nerves.

Adrenal Gland

Adrenal Cortex: 3 Zones: Zona Glomerulosa Cell clusters separated by fibrous septae. Secrete mineralocorticoids. (mainly aldosterone - acts on renal tubules to increase Na and H2O retention). Zona Fasciculata Columns of cells with abundant pale cytoplasm. One cell thick, separated by capillaries. Secrete glucocorticoids - mainly cortisol. Zona Reticularis Irregular group of cells Separated by wide capillaries Less lipid. This is the source of adrenal androgens like: -dehydroepiandrosterone (DHEA) and DHEA sulphate Secretes steroid hormones: Mineralocorticoids (Fluid and electrolyte balance.) Glucocorticoids (Carb and lipid balance) Sex hormones ======================= Adrenal medulla Clusters of cells with granular, basophilic cytoplasm. Very vascular. Secrete epinephrine and norepinephr. Turn brown in Chromium salt fixative: Chromaffin cells. Cells secreting noradrenaline (Na) more strongly positive.

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Afferent lymphatic vessels divide into branches outside the node and pierce the capsule to drain into a narrow space called the subcapsular sinus, which encircles the Lymph node beneath the capsule. From the sinus channels, called cortical sinuses, pass through the cortex to the medulla. In the medulla, the most prominent feature are broad lymphatic channels called medullary sinuses, which converge on the hilum. Lymph drains from the efferent lymphatic vessels.

Bile

Aids in lipid digestion in small intestine. Synthesised by all hepatocytes. Secreted into canaliculi which are formed by the plasma membranes of adjacent hepatocytes. Contains ATPase which suggests bile secretion is energy dependent. Also contain alkaline phosphatase such that elevated blood levels of hepatic alkaline phosphatase are a feature of obstructive jaundice. "Bile canaliculi: ATPase activity" Produced by all hepatocytes. Grooves in the plasma membrane of hepatocytes form bile canaliculi. Bile canaliculi fuse to form canals of Hering. Tight junctions separate them from vasculature. Bile canaliculi -> canals of hering -> bile ductules -> terminal bile ducts.

Low Power Structure of The Gonads

All the major glands are divided into lobules, each containing many secretory units, by fibrous septae. Occasional fat cells, (adipocytes) are seen. The proportion of these gets greater as individuals age. The striated ducts lead into larger excretory ducts. Excretory ducts found in fibrous septae alongside arteries and veins.

Muscle Tissue

All three types (smooth / skeletal cardiac) are surrounded by an elastic lamina, which binds the muscle cells into a functional mass. Contractile forces develop by internal contractile proteins, transmitting forces to the external lamina via link proteins in the cell membrane.

The Nervous System

Anatomically, 2 Parts: CNS (consists of brain and spinal cord) and PNS (connection between CNS and rest of body). Functionally 2 Parts: Somatic and Autonomic NS. Somatic is voluntary, autonomic is involuntary.

Cells of the skin

Apart from keratinocytes: Melanocytes: Produce melanin, responsible for skin pigmentation. More synthetically active in dark skinned people. (little difference in # between wh/bl) Melanocytes are also characterised by dendritic processes, which stretch between relatively large numbers of neighbouring keratinocytes. Ageing diminishes the melanocyte population. Melanin accumulates in melanosomes: transferred to adjacent keratinocytes where they remain as granules. Melanin provides protection against UV. Langerhans Cells: Star shaped, mainly found in the stratum spinosum, Antigen presenting, processing and recognising cells. They have an irregular, lobulated nuclei, with an almost clear cytoplasm. Merkel Cells: Touch receptors

Hepatic sinusoids

Are lined by discontinuous, fenestrated endothelium which has no basement membrane. Separated from the hepatocytes by a narrow space = space of Disse, which drains into lymphatics of the portal tracts. Sinusoid lining cells -fenestrated endothelium. -No BM (reticulin) framework. Microvilli -larger surface area for metabolic exchange. Space of Disse -Continuous with sinusoid lumen. -Bathes hepatocytes in plasma. -Drains into lymphatics in portal tract. (<-stick picture here)

Arterial System

Arterial system functions to distribute blood from the heart to capillary beds throughout the body. Contraction - systole. Blood is forced into the arterial system, leads to expansion of the arterial walls followed by recoil during a diastole. Expansion and recoil is a function of the elastic tissue within the arterial walls. Flow of blood to different organs is regulated by varying the diameter of vessels. The role of the circumferentially arranged smooth muscle -> this is under the control of the SNS (sympathetic) and the adrenal medullary hormones. The walls of the arteries have the 3 layered structure again, but are characterised by ELASTIN. The smooth muscle layer is thick relative to the diameter of the lumen. As the vessels become smaller, elastin decreases and the smooth muscle layer becomes more prominent. ELASTIC ARTERIES - Major distribution vessels e.g. aorta, carotid Tunica intima is a single layer of flattened endothelial cells supported by connective tissue rich in elastin and smooth muscle cells. With age, these cells accumulate lipid -> atherosclerosis develops. Tunica media is broad and very elastic. With elastin between the smooth muscle fibers. Tunica adventitia contains small vasa vasorum, (small arteries running in the tunica adventitia.These send arterioles and capillaries into the tunica media) which also penetrates the outer part of the tunic media. MUSCULAR ARTERIES - Distributing branches. Internal elastic lamina, located between intima and media, is well marked. External elastic lamina, located between media and adventitia, more variable, less prominent. ARTERIES - terminal branches supplying capillary bed. ARTERIOLES - terminal branches of the arterial tree, which supply capillary beds. Loss of elastic laminae and reduction in the number of muscle layers in the media. Tunica adventitia is thin and merges with surrounding supporting tissue.

Gastro-oesophageal junction

At junction of oesophagus and stomach mucosa abruptly changes to glandular secretory. (S)

Basic Tissue Staining

Basic dyes, including haematoxylin, have positive charge so bind to negatively charged tissue components. Acidic dyes have negative charge so bind to positively charged tissue components. Basophilia = BLUE if haematoxylin -nuclear chromatin -cytoplasmic RNA -certain extracellular matrix proteins (cartilage) Acidophilia = PINK if eosin -cytoplasmic proteins including cytoskeleton -intracellular membranes -most extracellular protein fibres eg. collagen

Thyroid Gland

Basic unit is the Follicle. Spheroidal structure lined by cuboidal epithelium. Gland divided into lobules by septae. . . . . . . . . . The Thyroid Gland is under the control of the Hypothalamus. It is unusual in the fact that it stores inactive hormone. When the gland is inactive, follicles distended with dark-staining colloid, and epithelial cells become flattened. When active, thyroid becomes taller, develops more cytoplasm; the colloid (Colloid is rich in a protein called thyroglobulin.) is paler, develops scalloped edges as colloid extracted. 25% of all the body's iodide ions are in the thyroid gland. Inside the follicles, colloid serves as a reservoir of material for thyroid hormone production while also acting as a reservoir for the hormones themselves. Thyroid hyperplasia - epithelial cells large, active, increased in number. Marked depletion of stored colloid. (disease called hyperthyroidism - Graves' disease) TRH = Thyrotropin releasing hormone Thyroid produces 2 major hormones T3 - tri-iodothyronine T4 - thyroxine also produces calcitonin - calcium homeostasis. Calcitonin is produced by C cells or para-follicular C cells. Small clumps between follicles. Calcitonin is the antagonist of PTH, as it lowers the blood calcium levels. (parathyroid hormone) These are involved in how quickly the body burns energy, makes proteins, and controls how sensitive the body should be to other hormones.

Alternative model = hepatic acinus

Berry-shaped unit of liver parenchyma, centred on a portal tract. Lies between two or more terminal hepatic venules. Divided into zones, 1, 2 and 3 with hepatocytes in different zones having different metabolic functions. More accurately reflects the physiology of the liver. Zone 1 - closest to portal tract. Zone 3 - hepatocytes here receive least oxygen, high in esterases, low in oxidative enzymes. Plates of hepatocytes -some are binucleate -variations in ploidy Interweave with sinusoids. Radiate outwards from terminal hepatic vein

Bile

Bile comes from the liver. it emulsifies fat so it is in droplets small enough to be susceptible to lipase. Combination of fat and lymph in lacteals has a milky appearance = chyle.

Appendix

Blind-ended, tubular sac attached to caecum. Part of large intestine. Masses of lymphoid tissue in submucosa. Glands spaced more widely than elsewhere in large intestine. Diffuse infiltration of lymphocytes.

Duodenum

Brunner's glands - produce abundant alkaline mucus to neutralise the acid contents entering the duodenum from the stomach. Brunner's glands are compound, tubular, mucous glands located in the submucosa of the duodenum. They fill this region so completely that the typical submucosal connective tissue is obscured. Essentially represent a continuation of the pyloric glands of the stomach. At the stomach / intestine junction, mucous glands of the pyloric mucosa are replaced by Brunner's glands of the duodenal submucosa. Meissner's plexus - the plexus comprises a network of unmyelinated nerve fibres, and associated ganglia. Also called submucosal plexus. Considered as part of the autonomic nervous system, part of the peripheral nervous system that largely acts independent of conscious control. (involuntarily)

Trachea

C-shaped rings of hyaline cartilage prevent collapse during inspiration. Bands of smooth muscle (trachealis) join free ends of rings posteriorly. Contraction of trachealis reduces trachea diameter, assists in raising intrathoracic pressure during coughing. Labeled Diagram showing histology of Trachea: . . . . . . . . . . . . ======================= Labeled diagram showing layers of Trachea. . . . . . . . . . . The tracheal glands are mixed glands of the compound tubuloalveolar type. They contain mostly mucous cells. Demilunes of serous cells often cap the mucous cells. Ducts of the glands pass through the lamina propria to empty onto the epithelial surface.

Antigen presenting cells (APC)

Include macrophage-monocyte type cells. Dendritic cells. (often surrounded by lymphocytes.) Antigen is taken up by APC and processed. Processed antigen is then bound to an MHC (major histocompatibility complex) and the MHC-peptide complex is exposed to the outside world.

Basement membranes

Called external lamina in nerve and muscle tissue. Sheet-like arrangements of E.C. matrix proteins which act as interface between support tissue and parenchymal cells. Provides metabolic support and binds to underlying support tissue, while controlling epithelial growth and maturation - acts as a barrier to downward epithelial growth. Composed of 3 layers Lamina lucida: relatively transparent layer abuts the plasma membrane of the basal epithelial cells. Lamina densa: intermediate electron-dense layer. Lamina fibroreticularis: broad relatively electrolucent layer which merges with supporting tissue underneath. Mainly type 3 collagen and fibronectin. Both lamina lucida and densa are largely made up of type 4 collagen and laminin. Selective permeability especially important in the kidney. Main constituents are the fibrous protein collagen type 4, and the structural glycoproteins laminin, entanctin and fibronectin. These appear to be produced by the epithelial cells, except for fibronectin, which fibroblasts produce.

Conducting and Cleansing System

Upper respiratory system Lined by respiratory epithelium with 2 cell types: Mucus-secreting: trap particulate matter. Ciliated: move surface mucus layer and dust. The upper respiratory system isVery vascular, this helps Warms inhaled air

Sertoli cells

Can be considered 'nurse' cells - preserve correct environment for spermatogenesis. Permanent population in outer portion of tubule. Pale staining oval nucleus. A major role is to define two separate and physiologically different compartments in the seminiferous tubule. The basal compartment, near the periphery, is sealed off from the luminal compartment by processes of adjacent Sertoli cells that reach out and make contact: where the processes are in contact they form occluding junctions. Below the junction (basal compartment) - diploid spermatogonia. Once these commence division, the cells send out new processes to "undermine" the forming spermatocytes, and seal off a new layer below them, then break the barrier above. This effectively transfers the haploid cells to the luminal side and seals off the diploid ones. Sertoli cells secrete: Anti-Mullerian hormone (AMH) secreted during the early stages of fetal life. Inhibin and activins - secreted after puberty, and work together to regulate FSH secretion. Androgen binding protein - (also called testosterone binding globulin) increases testosterone concentration in the seminiferous tubules to stimulate spermiogenesis. Oestradiol - aromatase from Sertoli cells converts testosterone to 17 beta oestradiol to direct spermatogenesis. Glial cell line-derived neurotrophic factor (GDNF) - has been demonstrated to function in promoting undifferentiating spermatogonia, which ensures stem cell self-renewal during the perinatal period. The ETS related molecules aka ERM transcription factor - needed for maintenance of the spermatogonial stem cell in the adult testis. Transferrin is a blood plasma protein for iron ion delivery.

Stomach Cardia

Cardia: small, mucus-secreting glands. Narrow, circular band <1.5-3cm. Mucosa contains simple or branched cardiac glands, coiled with large lumens. Most of the glands produce mucus and lysozyme. (which attacks bacterial walls) A few parietal cells are also found (HCl secreting) These glands are similar to the cardiac glands of the oesophagus. Glands secrete two types of mucus and associated endocrine cells secrete gastrin. Glands secrete acid-pepsin, as well as mucus Diagram . . . . . . . . .

Cartilage

Classified into 3 types Elastic cartilage Hyaline cartilage Fibro-cartilage E.C. matrix mainly composed of collagen fibres, which is an abundant ground substance, rich in proteoglycans and elastin fibres. Cartilage precursor cells are chondroblasts. Synthesise ECM around themselves. Chondroblasts mature into chondrocytes. Maintain cartilage. Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are supplied by diffusion, helped by the pumping action generated by compression of the articular cartilage or flexion of the elastic cartilage. Thus, compared to other connective tissues, cartilage grows and repairs more slowly. Surface perichondrium gives rise to new chondroblasts. - These regenerate cartilage. Most articular surface do not have perichondrium therefore cannot regenerate. Very poor blood supply. - Receives nutrients via diffusion.

Mature fibroblasts

Collagen fibres are dense and very pink. Fibroblast nuclei are condensed and elongated in the direction of the collagen bundles. Little cytoplasm. Its main function is to maintain the integrity of tissue by slow turnover of the extracellular matrix constituents. Variation in supporting tissues - may be loose e.g. bowel submucosa. Where more strength is needed, pink collagen bundles are more condensed. - muscle fascia ; (dura mater?)

Collagen

Collagen: Main type of fibre. Most abundant protein in the body. Provides tensile strength. Secreted as tropocollagen which polymerises in the extracellular matrix to form collagen. 2 types. Type 1 collagen: Found in dermis, tendons, ligaments, bone and fibrous supporting tissue. Bundles visible with light microscopy. Type 2 collagen: Found in hyaline cartilage, fine fibrils dispersed in the ground substance. Type 3 collagen (reticulin): delicate branching supporting meshwork in highly cellular tissues. - liver, bone marrow and lymphoid organs, absorb metallic silver by which they are stained black. Type 4 collagen: forms a mesh-like structure in basement membranes. Type 7 collagen: anchoring fibrils that link basement membrane.

Corpus Luteum

Collapsed ruptured follicle fills with blood. Granulosa cells become markedly enlarged. Steroid secreting cells - granulosa lutein cells Secrete Progesterone - orchestrates changes in secretory behaviour of lining of uterus. Theca interna cells continue to secrete oestrogen. Involuted corpus luteum = corpus albican, a fibrous scar. After ovulation ruptured follicle collapses, fills with a blood clot Under influence of LH from anterior pituitary granulosa cells increase in size & begin secretion of progesterone ( granulosa lutein cells) Progesterone acts on endometrium preparing it for implantation Cells of theca interna also increase in size + secrete oestrogens to maintain thickened uterine mucosa (theca lutein cells) Progesterone feeds back on pituitary to inhibit LH. Corpus luteum not able be maintained~12-14 days after ovulation regresses-corpus albicans-and secretion of progesterone and oestrogen ceases, thus the endometrial lining collapses = menstruation.

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Composed of cells in ECM given rigidity by calcium ECM is type I collagen: osteoid Cells: Osteoblasts - Synthesise osteoid and mineralise it - Link up on surface of bone Osteocytes - Inactive osteoblasts - Maintain nutrition of bone Osteoclasts - Phagocytic cells - Involved in bone turnover Osteoblasts and osteocytes are derived from a common osteoprogenitor cell.

Blood Vascular system

Comprises a circuit of vessels. Blood flow is initiated by continuous action of a central muscular pump, the heart. The arterial system provides a distribution network to the tiny peripheral microcirculation, which are the main sites of interchange between the tissues and the blood. Venous system carries blood from the capillary system back to the heart.

Peripheral Nervous system

Comprises the nerves which run between the CNS and other tissues. The PNS also has ganglia, which are nerve relay stations. (In the ANS, cell bodies lie in aggregations (ganglia) in peripheral sites.) All axons in PNS are enveloped by Schwann cells. Provide structural and metabolic support. These axons are either myelinated or non-mye. In PNS: Small diameter axon enveloped by just Cytoplasm of Schwann cells = non-myelinated. (these can be small nerves that are simply enclosed) Large diameter axon wrapped by variable concentric layers of Schwann cell plasma membranes = myelinated / myelin sheath. This serves to increase conduction velocity. Each Schwann cell forms myelin sheath for part of axon - internode. Distance between myelin sheaths - Node of Ranvier. (here, the axonal membrane is uninsulated and therefore capable of generating electrical activity.) Nerve action potential jumps from node to node - saltatory conduction. (Difference between CNS/PNS myelin sheath in CNS - oligodendrocytes and in PNS Schwann cells)

3 types of lamellar bone in the shaft of a long bone

Concentric lamellae Circumferential lamellae Interstitial lamellae The inner circumferential lamellae, deposited by the endosteum, encircle the marrow cavity. While the outer circumferential lamellae are laid down around the outside of the bone by the periosteum. Periosteum consists of dense irregular connective tissue. Periosteum is divided into an outer "fibrous layer" and inner "cambium layer" (or "osteogenic layer"). The fibrous layer contains fibroblasts, while the cambium layer contains progenitor cells that develop into osteoblasts. Endosteum = is a thin layer of connective tissue which lines the surface of the bony tissue that forms the medullary cavity of long bones.

Heart valves

Consist of leaflets of fibro-elastic tissue covered by endothelium on both sides. A central dense collagen plate called the lamina fibrosa is there. . . . . . .

Parotid gland

Consists mainly of serous cells. Thin watery secretion rich in enzymes and antibodies. Large striated ducts to convert saliva to hypotonic solution. The secretion produced by the parotid glands is serous in nature. Enters the oral cavity through Stensen's duct after passing through the intercalated ducts which are prominent in the gland. Despite being the largest pair of glands, only approximately 25% of saliva is produced by the glands.

Endocrine system

Consists of Pituitary gland Thyroid gland Parathyroid gland Adrenal gland Endocrine Pancreas Pineal Gland The Diffuse neuroendocrine system

Submandibular Gland

Consists of a mixture of serous and mucous cells, often found as mixed seromucous secretory units. Serous demilunes are seen. The paired submandibular glands (submaxillary glands) are salivary glands located beneath the floor of the mouth. In humans, they account for 70% of the salivary volume and weigh about 15 grams The secretory viscous cells of the submandibular gland have distinct functions The serous cells are the most active and therefore the major product of the submandibular glands is saliva In particular, the serous cells produce salivary amylase, which aids in the breakdown of starches in the mouth Mucous cells secrete mucin which aids in the lubrication of the food bolus as it travels through the oesophagus.

Glycocalyx

Consists of acidic mucopolysaccharides and glycoproteins that project from the apical plasma membrane of the epithelial absorptive cells. It provides additional surface for adsorption, and includes enzymes secreted by absorptive cells that are essential for the final steps in digestion of proteins and sugars.

Lymphocytes:

Constitute around 20-50% of WBC in circulation. Numbers increase in response to viral infection. Lymphoid cells have round/oval nuclei with dense chromatin and nucleoli which are not usually visible and often very little cytoplasm. B lymphocytes produce antibody, T lymphocytes have several subtypes and act as suppressor cells, cytotoxic cells and helper cells.

Post-menopausal/Atrophic phase of Endometrium

Cyclical production of hormones ceases. Atrophic changes in endometrium and myometrium. Uterus shrinks. Glands become cystically dilated.

Upper GI possible questions

Describe the various papillae of the tongue and discuss their functions. How does the mucosa change from the oesophagus to ileum and how does this relate to function? Write short notes on Peyer's patches. Label diagram seen on slides.

Differences epithelium, lamina propria, Submucosa, Muscularis propria

Duodenum: Epithelium- Simple columnar, goblet cells, Paneth cells. Lamina Propria - No Peyer's patches Submucosa - Brunner's glands, and Meissner's (submucosal) plexus. Muscularis propria - longitudinal and circular layers, with Auerbach's (myentric) plexus in between. Jejunum - somewhat similar to duod. Epithelium - similar to duod. long villi Lamina propria - few Peyer's patches. Submucosa - No Brunner's glands. Ileum - similar to duod. Epithelium -similar to duod. short villi Lamina Propria - Peyer's Patches Submucosa - No Brunner's glands.

Jejunum and ileum

Differences from duodenum. Villi longest in duodenum, shorter towards ileum. Lymphoid tissue becomes more prominent in the ileum, inconspicuous in duodenum. Proportion of goblet cells increase towards ileum. (= increases distally) Plicae circulares: only found in jejunum & ileum, absent in proximal duodenum and distal ileum.

Spinal Ganglia

Discrete aggregations of neuron cell bodies outside CNS. Lie on posterior nerve roots of spinal cord as they pass through intervertebral foramina. Neurons are of pseudo-unipolar type.

Lecture 1: Basic Membrane structure

Electron micrograph shows trilaminar layer in a basic membrane. 1.) outer electron-dense 2.) central electron-lucent ---- Nucleus is heterogeneous: Electron dense Heterochromatin: inactive coiled chromatin Electron lucent Euchromatin: DNA involved in RNA synthesis

Myoepithelial cells

Embrace the acini and, on contraction, force the secretions from the acinar lumen into the duct system. Located between the basal plasma cell membranes of secretory cells and the basement membrane. Flattened cell with long cell processes which extend around the acinus.

The Pancreas

Embryological development = outgrowth of primitive foregut Exocrine and endocrine components - pancreas is a dual-function gland. Exocrine: bulk of gland, alkaline enzyme-rich secretion. Trypsin and chymotrypsin (secreted in inactive form) digest proteins, carbohydrates, lipids and nucleic acids. Endocrine: islets of Langerhans, produce insulin and glucagon. Pancreatic secretion: Continuous, but rate modulated by hormonal and nervous influences. Secretin (produced by diffuse neuroendocrine cells of duodenum) promotes secretion of water fluid rich in bicarbonate. Cholecystokinin-pancreozymin (CCK) stimulates enzyme-rich pancreatic fluid. Gastrin (neuroendocrine cells of gastric pylorus) has similar effect to CCK. Pancreatic juice contains sodium bicarbonate which neutralises the acidic material from the stomach. Pancreatic amylase digests starch to maltose. Trypsin and Chymotrypsin digest proteins to peptides. Like pepsin (produced in the stomach), they are specific for certain amino acids, not all of them. Lipase digests fats to glycerol and fatty acids. Why doesn't the pancreas digest itself? Secretion is continuous, but rate is tightly controlled. Vagal nerve - acetylcholine Hormones - Secretin (H2O / bicarbo) Cholecystokinin (enzymes) Both secreted by duodenum triggered by acid load, fatty acids and protein digestive product. Enzymes secreted in inactive state.

Epididymis

Epididymis is lined by a columnar epithelium adorned at its surface with large microvilli. Resemble the cilia found in other parts of the body. This similarity in appearance led to them being dubbed "stereocilia". BUT they are not cilia. Cilia have internal microtubules and are capable of movement, "stereocilia" do not. They're filled with cytoplasm ~ structures for absorption, not movement, of fluids. The epididymis is an absorptive and secretory organ. Sperm have to spend some time in the epididymis to be "capacitated" before capable of fertilizing an oocyte. Lining epithelium produces glycoprotein material that coats the sperm. Secretory nature of the epithelium - large and easily-seen Golgi apparatus in lining cells.

The Heart layers

Endocardium / Tunica Intima - Surface layer flattened endothelial cells. Fibrous layer containing various amounts of elastic tissue. It has become evident that the endocardium, which primarily is made up of endothelial cells, controls myocardial function. Epicardium / Visceral Pericardium / Tunica adventitia - dense sheet of fibro-collagenous and elastic tissue. On outer surface, a single layer of flat mesothelial cells (simple squamous epithelium) is responsible for secreting lubricating fluid. Myocardium / Tunica media - Made up of cardiac muscle fibers. They form an interconnecting network and are joined to each other by intercalated discs. Cardiac muscle cells have central nuclei and regular cytoplasmic striations. Intimate and extensive capillary network because of the high and constant O2 demand. Purkinje fibres - Modified cardiac muscle fibres. Involved in regulating coordinated contraction of heart. Derived from atrioventricular bundles (of His?) Run immediately below endocardium / tunica intima.

Bone development and growth

Endochondral ossification: - Cartilage models replaced by bone - Cartilage bones • Long bones, vertebrae • Pelvis, base of skull Appositional growth. Chondrocytes resorb cartilage. Osteoblasts grow in from periostium. Replacement of cartilage by bone. Growth plates replaced by bone. Allows functional stresses to be maintained during bone growth. Formation of small 'model' in hyaline cartilage . Shaft = diaphysis, future articular portions = epiphyses. Within shaft of cartilage model chondrocytes enlarge, resorb surrounding cartilage. Cartilage matrix becomes calcified and chondrocytes degenerate. Perichondrium gradually assumes role of periosteum ~ lays down thin layer of bone around surface of shaft Primitive mesenchmal cells invade spaces left by degenerated chondrocytes - differentiate into osteoblasts - form irregular woven bone. Ends of the original cartilage 'model' are separated by a large site of primary ossification. Interface between shaft and each epiphysis constitutes a growth or epiphyseal plate. Within the growth plate the cartilage proliferates continuously ~ progressive elongation of bone. At diaphysial aspect the chondrocytes die and degenerating carilage zone is replaced by bone. At maturity hormonal changes inhibit further proliferation ~ growth plates replaced by bone. Fusion of diaphysis and epiphyses. Meanwhile in centre of mass of cartilage of each developing epiphysis get secondary ossification.

Enzymes of Pancreas

Enzymes secreted as proenzymes Except amylase & lipase Contained in zymogen granules (can be degraded by lysosome if ducts obstructed) Trypsin can be inactivated Trypsin inhibitors present Trypsin can inactivate itself Acinar cells are resistant to their enzymes Trypsin, chymotrypsin & phospholipase A2 Where are these enzymes made? In the pancreatic ACINI Eosinophilic granular apex (zymogen granules) Cells of each acinus have triangular shape Nuclei are basally located surrounded by basophilic cytoplasm Apices packed with eosinophilic secretory granules (proenzymes). Lumen -> intercalated duct -> intralobular duct -> interlobular duct.

Basic layers of the skin

Epidermis: the external layer mainly composed of layers of keratinocytes but also containing melanocytes, Langerhans cells, Merkel cells and inflammatory cells. Basement membrane: multilayered structure forming the dermoepidermal junction. Dermis: The area of supportive connective tissue between the epidermis and the subcutis. The dermis contains sweat glands, hair roots, nervous cells, fibres, blood and lymph vessels. Subcutis (Hypodermis): The layer of loose connective tissue and fat beneath the dermis.

Synovial joints

Extensive movement Articular surfaces coated with synovial fluid. Synovial cells are of mesenchymal origin. No basement membrane No cell-cell junction. Contains numerous blood vessels, lymphatics and nerves. Synoviocytes produce synovial fluid - major constituents are hyaluronic acid and glycoproteins. Drawing of a synovial joint . . . . . . . . . Study graphs of how -hyaline cartilage -fibrous capsule -extensor tendon -synovum -articular cartilage -cortical bone -periosteum are laid out.

Bone structure 2

Fatty marrow Trabecular bone Articular cartilage Compact bone Trabecular / cancellous bone - interconnecting struts of lamellar bone around haemopoietic/fat space. Trabeculae covered by inconspicuous layer of endosteum.

Histology of the vagina

Fibromuscular canal Stratified squamous epithelium, lamina propria,outer fibromuscular adventitial layer Contraction after coitus helps retain semen Capable of considerable stretching during delivery.

Thymus

Flattened lymphoid organ. In upper anterior mediastinum and lower part of the neck. Most active during childhood, heaviest at puberty and then undergoes involution. Structure: Thymus originates as epithelial outgrowths which merge in the midline forming an organ with fine lobules. Epithelium develops into a sponge-like structure containing numerous interconnecting spaces which are colonised by immature T cells. In the centre, the epithelial meshwork is coarser with a smaller lymphocyte population so the gland has an outer cortex and a less cellular central medulla. Drawing representing thymus . . . . . . . . . . Functions: development of immunocompetent T lymphocytes from T cell precursors derived from BM. Development of self-tolerance. Proliferation of clones of mature naive T cells to supply the lymphocyte pool. Secretion of hormones which regulate T cell maturation, proliferation and function.

Cerebellum

Forms deep fold known as folia. Consists of cortex of grey matter with central core of white matter. Coordinates muscular activity and posture. Central core of white matter contains 4 pairs of nuclei. Molecular Layer Granular Layer Purkinje Cells (lie between ML and GL) Purkinje cells are huge neurons. Have extensive arborising dendritic system. Afferent fibres enter the cerebellum from the brain stem. Pass via white matter to make connections with the granular layer - then connect to Purkinje cells. The only fibres leaving (efferent) the cerebellum are the Purkinje cell axons - down through granular layer to central nuclei.

The circulatory system

Functions: Mediates continuous movement of all body fluids. Transport oxygen and nutrients to tissues. Transport of carbon dioxide and metabolic waste products away from tissues. Temperature regulation. Distribution of molecules and cells e.g hormones,immunocytes

Liver

Functions: Fat metabolism - oxidising tryiglycerides to produce energy - synthesising plasma lipoproteins - synthesising cholesterol and phospholipid. Carbohydrate metabolism - converting carbs and proteins into fatty acids and triglyceride. - Regulating blood glucose concentration by glycogenesis, glycogenolysis, and gluconeogenesis. Protein metabolism Synthesising plasma membrane proteins (albumin, clotting factors) Synthesising non-essential amino acids. Detoxifying metabolic waste products. - e.g. deamination of amino acids, production of urea. Storage - glycogen, vitamins, iron. Intermediary metabolism - detoxifying various drugs and toxins, including alcohol. Secretion - synthesising and secreting bile.

The Respiratory System

Funnel-shaped space Relatively rigid chest wall and diaphragm Expansion of space Produces negative pressure Air enters lungs Extends lung tissue Elasticity of lung tissue causes reversal Air leaves lungs Conducting and cleansing: Nasal cavity Larynx Trachea Primary, secondary, tertiary bronchi Bronchioles Terminal bronchioles

Hormones of the pituitary gland

Group 1. Those acting on non-endocrine tissues: -Growth hormone (GH) -Anti-Diuretic hormone (ADH) -Prolactin -Oxytocin -Melanocyte stim. hormone (MSH) Group 2. Those modifying the secretory activity of other endocrine tissues: -Thyroid stimulating hormone (TSH) -Adrenocorticotrophic horm. (ACTH) -Follicle stimulating hormone (FSH) -Luteinising hormone (LH) Thus the thyroid, adrenal and gonads are known as pituitary-dependent endocrine glands. ======================= ADH (vasopressin) is synthesised in the supraoptic nucleus. Oxytocin is synthesised in the paraventricular nucleus Both pass down axons of hypothalamopituitary tract. Secretion process called neurotransmission.

Epidermal skin appendages

Hair follicles: produce hair shafts composed mainly of keratin. Sebaceous glands: majority associated with hair follicles. Secrete sebum which provides waterproofing. Some sites (breast areolae, buccal mucosa) open directly onto skin or mucosa. These cells are packed with lipid filled vacuoles. Involved in Holocrine secretion (done by holocrine glands): discharge of whole cells. Eccrine sweat glands: normal found everywhere Apocrine glands: (mainly axilla / armpit / groin and areolae of breast) In animals used as 'scent' producer. Low cuboidal epithelium, eosinophilic cytoplasm. Myoepithelial cells are present.

Liver further.

Has a dual-blood supply. Hepatic artery - carries O2 from the heart. Portal vein - carries nutrient-rich blood from GIT. Porta Hepatis - hilum. Hepatic sinusoids form low-resistance system of vascular channels allowing blood to come in contact with hepatocytes over huge area. This close association is essential for normal function. The hepatic lobule is a structural unit, hexagonal in its shape, centred on terminal hepatic (centrilobular) venule. The blood flows from the portal vein and hepatic artery in portal tract to central veins. Blood flows along sinusoids lined with endothelial cells. There is a close association with hepatocytes, allowing absorption of nutrients and secretion of hepatic products. Hepatocytes - large polyhedral epithelial cells, round nuclei, prominent nucleoli. More than half the hepatocytes contain twice the normal complement of chromosomes. (i.e. are TETRAPLOID) Binucleate cells are common. Irregular unstained areas where glycogen and lipid have been removed during processing.

Cortex of lymph nodes

Highly cellular area called cortex, consists of densely packed lymphocytes, Cellular medullary cords project into the medulla between the medullary sinuses. In outer cortex: lymphocytes form densely packed lymphoid follicles, which may show germinal cetres. (GC) Deep cortex is devoid of lymphoid follicles. lymphoid follicles in LN: Major sites in which B lymphocytes localise and proliferate. Classified as: primary (no germinal centre present) or secondary (GC is present) GC: site of B cell proliferation and is pale because the nuclear chromatin is not condensed. GC is pale, (especially towards capsule end) surrounded by darker mantle zone. Periphery of the mantle zone is slightly paler and is called the marginal zone. Mantle zone composed of small resting lymphocytes and is asymmetric and broader on the side nearest the capsule. Resting B cells enter the lymph node and if they encounter antigen, with which they react, they enter blast transformation to produce clones and memory cells. -> The first step is activation which produces centroblasts. Centroblasts: Large mitotically active cells with round nuclei found at the darker end of the GC. Differentiate into centrocytes which are of variable size and have folded irregular nuclei. No mitotic figures, but tingible body macrophages are present. Other cells in Germinal Centres. Follicular dendritic cells: Major APC of the follicles. Tingible body macrophages: contain apoptotic bodies in their cytoplasm, they also contain condensed chromatin fragments. Deep cortex (paracortical areas) Mainly T lymphocytes which are never arranged as follicles. Medullary cords are mostly B cells and plasma cells producing antibody.

Saliva

Hypotonic watery secretion containing: -mucus -enzymes (amylase and lysozyme) -antibodies (IgA) -inorganic ions (Overall composition of saliva will vary according to which of the glands is most active.) Salivary secretion Minor glands secrete continuously and are under local control. Major glands secrete in response to parasympathetic activity, which is induced by physical, chemical and psychological stimuli. Daily saliva production in humans ranges fro 600-1500mL. Salivary secretory unit - These are terminal branched, tubulo-acinar structured secretory units, composed of serous cells, mucous cells or both. In mixed secretory units, where mucous cells predominate, a semilunar cap of seros cells called a serous demilune is seen. Draw a basic saliva secretory unit . . . . . . .

Layers of the Cerebral Cortex

I = Plexiform/molecular layer Dendrites and axons + horizontal cells of Cajal II = Outer granular layer Axons, dendrites. Small Pyr cells and stellate III = Pyramidal layer Pyr cells predominate and Martinotti cells IV = Inner granular layer Stellate cells mainly V = Ganglionic layer Large Pyr cells + Martinotti cells VI = Multiform layer Numerous cells of different morphological type Drawn if possible . . . . . . . .

Multiple Sclerosis

Immune mediated destruction of myelinated axons in the CNS. Leading to demyelination and scarring, as well as a broad spectrum of signs and symptoms. In healthy nerve, intact myelin, K+ channels covered, Normal conduction Unhealthy nerve, Disrupted myelin, K+ channels exposed, conduction failure.

Fibrocartilage

In fibrocartilage chondrocytes are far less numerous and much more widely separated than in other types. They tend to be arranged in somewhat regular rows rather than the obvious isogenous groups of hyaline or elastic cartilage.

Leydig cells / Interstitial cells

In the regions between the seminiferous tubules, (outside the adjacent boundary layers) run small amount of CT. Here there are many capillaries, as is true of all such CT regions. Another population of cells - not part of the germ line. Small groups of cells which produce the male steroid hormone Testosterone. The pituitary hormone (ICSH - Interstitial cell stimulating hormone) is the trigger for the interstitial cells to start making testosterone at the onset of puberty.

Trachea cell populations

In trachea comprises 5 cell populations: Ciliated pseudostratified columnar cells Goblet cells Serous cells Basal cells: Neuroendocrine cells Basal stem cells

Infundibulum fimbrae

Infundibulum and fimbriae overlie the site of ovulation. Directed movement of ovum toward uterus by gentle peristalsis and cilia. Fertilisation usually occurs in the Ampulla. Mucosa in folds called plicae, Smooth muscle in longitudinal and circular layers.

Pituitary Gland (Hypophysis)

Is under the control of the hypothalamus, while also being a protrusion of the hypothalamus. About the size of a pea. Sits in the sella turcica -Anterior Pituitary (Adenohypophysis) Pars tuberalis Pars intermedia Pars distalis The anterior pituitary has 2 main population of cells. Chromophils (A and B) - strongly staining cytoplasm (dark stain) / basophils and acidophils Chromophobes - Weakly staining (pale) cytoplasm, few secretory granules, may produce any of the hormones. Anterior pituitary is ectoderm, and an upgrowth from roof of primitive oropharynx Five cell types in the anterior Pituit. Somatotrophs (50%) - GH secretion Acidophil Mammotrophs (20%) - Prolactin - acidophil - increase during pregnancy Corticotrophs (20%) - ACTH (adrenocorticotrophic hormone) derived from pro-opiomelanocortin) basophil Thyrotrophs (5%) - TSH - basophil Gonadotrophs (5%) - FSH / LH - basophil ======================= Pars intermedia - Derived from remnants of Rathke's pouch. Composed of basophilic cells. Lies between AP and PP Contains endorphins Produces MSH in foetal life ======================= -Intermediate lobe - in humans just a few cells thick. Generally, the hormones secreted from here are involved in homeostatis. ======================= -Posterior pituitary (Neurohypophysis) Infundibular stalk Pars nervosa Formed / composed of non-myelinated axons with cell bodies in the supraoptic and paraventricular nuclei of hypothalamus. Axons form the hypothalamohypophysial tract. Terminates in pars nervosa. Secretory granules present all along axons. Most numerous in terminal distensions where they meet capillaries: Herring bodies (ADH and Oxytocin). Herring bodies are the dilated hypothalamic nerve terminals from the hypothalamus from which the posterior pituitary actually releases ADH and Oxytocin. ADH and Oxytocin are released from different Herring bodies, reflecting their separate origins. Posterior pituitary is neuroectoderm, downgrowth from the floor of the 3rd ventricle. Maintains link with hypothalamus by neural tract. Drawing representing Pituitary, including the vestigial cleft neural stalk, pars tuberalis etc. . . . . . . . . . .

Endocrine Pancreas

Islets of Langerhans < in tail Grouped around strands of capillary networks. 3 major cell types Alpha (glucagon) Beta (insulin) Delta (somatostatin) Also vasoactive intestinal peptide and pancreatic polypeptide. Endocrine cells within islets are arranged as irregular cords around abundant capillaries, which receive the secreted hormones for delivery into the systemic circulation.

Endocrine Pancreas

Islets of Langerhans Most numerous in tail Groups and strands of cells around capillary network. Three types of cells A - alpha - 15-20% - Red - Glucagon B - beta - 60-70% Brown - Insulin D - delta -5-10% Blue - Somatostatin

Additional cells lining sinusoids

Kupffer cells -large plump cells, ovoid nuclei. -Monocyte/phagocyte system-removal spent erythrocytes. -found in sinusoids Stellate cells/Ito cells/Hepatic lipocyte -fat storage, lipid droplets contain vitamin A -Production of ECM and collagen. -Space of Disse. -Appear to produce excess collagen during cirrhosis.

Bone structure

Lamellae Haversian Canal Haversian system Volkmann's canals Periosteum Endostium Interstitial systems = remnants of lamellae no longer surrounding Haversian systems.

Stomach fundus and body

Lamina propria has abundant number of gastric glands. The distribution of epithelial cells is not uniform. Each gastric gland has 3 main areas: isthmus, neck and base. Labeled diagram of fundus and body . . . . . . . . . .

Spleen

Large lymphoid organ in the upper part of the abdomen. Receives a rich blood supply via a single artery, the splenic vein into the hepatic portal system. 2 main functions: provide immune response against blood borne antigens and removal of particulate matter and old and defective blood cells. Macroscopically, the spleen consists of discrete 05-1mm white nodules: the white pulp embedded in a red matrix called the red pulp. Microscopically: the WP consists of lymphoid aggregates and the RP, making up bulk of organ, is highly vascular tissue. The spleen also has a thin but dense fibroelastic outer capsule from which short trabecullae extend into the parenchyma. Capsule is thickened at the hilum. In WP, the cell areas surround the central arteries forming the periarteriolar lymphoid sheath. (PALS) The central artery is surrounded by white cells, constituing periarterial sheath. Spleen red pulp Splenic parenchyma permeated by an interconnected network of sinuses which drain into larger sinuses which then drain into splenic vein. Sinuses are lined by flattened endothelial cells resting on a basement membrane interrupted by narrow slits. Red pulp removes particulate matter and aged and abnormal RBC from the bloodstream. Defective cells are less deformable and cannot pass through narrow slits. Splenic White pulp T cells and B cells together make up 5-20% of the total mass of the spleen. T cells form an eccentric sheath around a central arteriole. B cells form follicles usually located in the vicinity of the arteriole and in young people can have a GC.

Stomach pylorus

Latin expression: gatekeeper The gastric pits are deeper and communicate with pyloric glands. Mucus and lysozyme is secreted. Gastrin (G) cells which release Gastrin are seen which are neuroendocrine cells and are found in between mucus secreting cells. They activate the parietal cells. Parasympathetic stimulation, aminoacids and stomach distention directly stimulate G cells to secrete Gastrin. Also D cells are present. -> they secrete somatostatin. Somatostatin inhibits the release of gastrin, it is stimulated by HCl and counterbalances acid secretion.

Nasopharynx

Lined by respiratory epithelium - pseudostratified ciliated epithelium With age may be replaced by areas of squamous epithelium. Lamina propria is rich in lymphoid tissue. Part of Waldeyer's ring (protects entry portals of GI and respiratory systems). Waldeyer's ring - an interrupted circle of protective lymphoid tissue at the upper ends of the respiratory and alimentary tracts. Lymphoid tissue particularly prominent in children; bulges out into lumen=adenoids

Pineal Gland

Located deep in the centre of the brain. Connection to light. Synthesises melatonin - Which induces rhythmical changes in endocrine activity. Pinealocytes are chief cells - secrete melatonin into capillaries via long axons - modified neurons. Neuroglial cells - support pinealocytes. They are modified astrocytes. (Astrocytes are: Highly branched support cells. Provide mechanical support. Mediate exchange of nutrients. Repair following injury. Termination of astrocytic processes upon basement membranes of capillaries = Perivascular feet (these form part of the blood-brain barrier) Basophilic pineal sand - salts of calcium, magnesium and silicon; feature of ageing gland. At high magnification, three types of nuclei can be distinguished. Small dark nuclei - astrocytes Larger, lighter, round nuclei - Pinealocytes. (surrounded by a broad rim of light cytoplasm). Most nuclei present are the nuclei of pinealocytes. Endothelial cell nuclei - are found in association with the vessels and capillaries traversing the tissue. Both pinealocytes and astrocytes have long processes which give the tissue between the nuclei its "stringy" appearance.

Cells of the jejunum and ileum

Look into crypts of Lieberkuhn. Majority of cells in crypt bases are stem cells. Goblet cells - immature in crypt. Paneth cells - part of the innate immune system, contain anti-microbial peptides (defensins) and protective enzymes = Phospholipase A and lysozyme. Long lived cells (weeks) versus enterocytes / goblet cells (3-5 days). - When exposed to bacteria or bacterial antigens, Paneth cells secrete a number of antimicrobial molecules into the lumen of the crypt. Endocrine cells cells - hormones like secretin (first hormone discovered), serotonin, somatostatin.

Venous system

Low pressure compartment, responsible for carrying blood from capillary networks to the right atrium of the heart. Back-flow is prevented by the presence of valves. Valve failure leads to varicose veins. Also conforms to the 3 layered arrangement of the circulatory system, but elastic and muscular components are much less prominent. Post-capillary venules, (PCV) are formed by the confluence of several capillaries. These drain into vessels of increasing diameter and gradually acquire smooth muscle layer that is 2-3 cell layers thick. These vessels are now called muscular venules. Veins have a much thicker muscular wall with poorly developed internal elastic lamina. Tunica adventitia is continuous with the surrounding supporting tissues. Inferior vena cava - Largest vein in body together with superior vena cava, returns deoxygenated blood to right atrium. Thickest wall of all veins with distinct lamina, narrow media and thick adventitia. Circular smooth muscle present in media, and longitudinal smooth muscle fibers within the adventitia.

Lymphoreticular cell types

Lymphocytes: B lymphocytes produce andtibody, T lymphocytes have several subtypes and act as suppressor cells, cytotoxic cells and helper cells. Antigen presenting cells: Including macrophages and B lymphocytes, control activation of the T cells.

Mucosa associated lymphoid tissue

Lymphoid tissue is present throughout the GIT either diffusely or as large discrete non-encapsulated aggregates. e.g. tonsils, and intestinal Peyer's patches. Smaller aggregations and diffuse populations are seen in the tracheobronchial tree and Genito Urinary tract. The amount of tissue present is extremely large and is known collectively as mucosa-associated lymphoid tissue. Larger aggregation function as lymph nodes do. Diffusely scattered lymphocytes are mainly T cells with smaller numbers of B cells.

Paracortical zone

Main cells are T lymphocytes. When activated, T cells enlarge to form immunoblasts before mitotic proliferation. Main APC: interdigitating dendritic cell, with numerous cytoplasmic processes which form a meshwork.

Arterioles and Microcirculation

Microcirculation - Exchange of fluids, gases, nutrients and waste products occurs in capillaries. Blood flow within the capillary beds is controlled by arterioles and precapillary sphincters. The capillaries drain into venules, collecting venules and small muscular venules respectively. Capillaries - Single layer of flattened endothelial cells line the lumen. Nuclei bulge into capillary lumen. Muscular and adventitial layers are absent. Occasional pericytes embrace the capillary endothelial cells and may have a contractile role.

Hyaline Cartilage

Most common Nasal septum, larynx, trachea, ribs, joints. Picture showing the layers of hyaline cartilage in trachea. . . . . . . . . . Chondrocytes individually are small cells with an oval nucleus and one or two nucleoli. Shrinkage associated with preparation makes it difficult to make out the details of these cells with the light microscope, but they have a rough surface and numerous processes that can be visualized in the electron microscope. Chondrocytes are derived from the same stem cell line that, in other locations, leads to the fibroblasts. As they secrete matrix material around them, the chondrocytes become walled off into small chambers or lacunae. The cells are grouped into small clusters. These "cell nests" are referred to as isogenous groups. They represent several generations of daughter cells that arose from the same chondroblast.

Osteoblasts, clasts, cytes

Osteoblasts and osteocytes are derived from a common osteoprogenitor cell. Osteoblasts are columnar or cuboidal shaped, with eccentric nuclei and perinuclear halo. - These cells also have polarity, with the cytoplasm toward the bone but the nuclei at the end away from the bone. Osteoclasts sit in a bony depression caused by resorption. (Howship's lacuna)

Gall bladder

Muscular sac lined by simple columnar epithelium. 100mL capacity in humans. Presence of lipid in duodenum promotes secretion of cholecystokinin, (CCK) by neuroendocrine cells of duodenal mucosa - this leads to contracting and forcing of bile into duodenum. Facilitates hydrolysis by pancreatic lipases. Intrahepatic bile collecting systems merge form right and left hepatic ducts. Create single large common hepatic duct. On leaving liver is joined by cystic duct which drains gall bladder, forms common bile duct. labeled diagram of gall bladder, cystic duct, common hepatic duct, and common bile duct. . . . . . . . . . Gall Bladder simply: Muscular sac Simple homogenous columnar epithelium loose submucosa rich in elastic fibres, blood vessels and lymphatics. Lining cells concentrate bile 5-10 fold by acitve process, resulting water passing into lymphatics of lamina propria. Only 1 muscle layer. Serosa Function - Concentrate and store bile (fat emulsifying agent)

Oesophagus

Muscular tube which transports food from the mouth to the stomach. Transport is driven by peristaltic contractions. Lower oesophageal sphincter and the upper oesphogeal sphincters also contribute. Lined by non-keratinised squamous epithelium. In the sub-mucosa there are groups of small mucus-secreting glands = oesophageal glands. Lubrication and protection. Near the stomach oesophageal cardiac glands are within the Lamina Propria = secrete mucus. Oesophagus layer drawing . . . . . . . .

Histology of Cervix

Neck of womb Projects into upper vagina Endocervical canal lined by mucus secreting glands Ectocervix - thick, protective stratified squamous epithelium

Nerve Cell - Neuron

Neuron is used to deliver rapid communication. Consists of 3 parts - Cell Body, Dendrites and Axon. Cell Body - Contains nucleus surrounded by cytoplasm (perikaryon) Generally, the cell bodies of all neurons are located in the CNS, with the exception of primary sensory neurons and the terminal effector neurons of the autonomic nervous system. In the ANS, cell bodies lie in aggregations (ganglia) in peripheral sites. Dendrites - Supply a sensory input. Axon (nerve fibre) - Terminates in efferctor organ or another neuron. Three types of neurons: Bipolar: Two processes extending from cell body, (dendrite and axon) - retinal cells, and olfactory epithelium. Multipolar: Multiple processes extending from its cell body; one of the extensions would be an axon and the rest would be dendrites. - spinal cord motor system and Purkinje cells. Pseudo-unipolar neurons: Two axons, rather than one axon and one dendrite. Extend from the spinal cord to connect it to skin or muscle cells. Ultrastructural aspects of a neuron. Nucleus - large, round or ovoid, chromatin dispersed, prominent nucleolus. Cytoplasm - large aggregations of ER (Nissl substance) Neuron types of cerebral cortex Pyramidal cells - shaped like pyramid with apex directed towards cortical surface. Stellate (granule) cells - small, appearance like small granules. Cells of Martinotti - smallish, polygonal cells; axon runs toward the surface. Fusiform Cells - spindle shaped, oriented at right angels to the surface of the cerebral cortex. Horizontal cells of Cajal - small and spindle shaped, But oriented parallel to the surface. Only found in most superficial surface.

Non-synovial joints

No free articulating surfaces - joined by dense collagenous tissue. Dense fibrous tissue - snydesmoses - Sutures of skull bones. Hyaline cartilage - (synchondrosis) - 1st rib with sternum. Fibrocartilage joints (symphyses) - intervertebral discs.

Long Bones

Outer compact cortical bone Inner cancellous medullary bone. Both compact and spongy bone are lamellar forms. The greater part of a long bone is the shaft, or diaphysis. The outer surface of the shaft is covered with a tough collagenous CT, the periosteum.

Ovary

Outer portion of the ovary - cortex. includes all of the ovarian follicles. Inner portion - medulla Contains larger blood vessels. Micrograph of Ovary - labeled . . . . . . . . . . . . . .

CNS

Overall structure of the CNS Arrangement of neurons in outer part of the brain = cortex Arrangement of neurons in discrete focus = nucleus Neuronal cells running along spinal cord = column Axons running in white matter = tract or fascicle. Brain forms complex folds, where clefts are called sulci. Outfoldings are called gyri. Cerebral hemispheres consists of cortex of grey matter overlying medulla of white matter. Grey matter: Neuron cell bodies and axons / neurons + supporting cells (astrocytes / oligodendroglia) White matter: Tracts of nerve fibres, mostly myelinated. Very little ECM in CNS. Within the CNS, myelination is consequence of the myelin sheaths being formed by oligodendrocytes. Cells of the CNS Neurons 1 axon extends from the cell body. Constant diameter throughout length. The ones passing through white matter are myelinated. Supporting cells Neurons are supported by neuroglia, which form almost 50% of CNS. (oligodendrocytes / astrocytes / microglia and ependyma) -Oligodendrocytes Form myelin. fewer processes than astrocytes. smaller than astrocytes. In grey matter seen close to cell bodies of neurons = perineural satellites. Rounded nuclei -Astrocytes Most numerous glial cells in grey matter. Highly branched support cells. Provide mechanical support. Mediate exchange of nutrients. Repair following injury. Termination of astrocytic processes upon basement membranes of capillaries = Perivascular feet (these form part of the blood-brain barrier) -Microglia Resident macrophages. Constitue 20% of glial population -Ependymal cells Epithelial cells, cuboidal or low columnar shape. Line ventricles and spinal canal. No basement membrane (unlike other epithelia). Absorptive and secretory function. Variable number of cilia and microcilia. Within the brain's ventricles, a population of modified ependymal cells and capillaries together form a system called the choroid plexus, which produces the cerebrospinal fluid. (CSF) -Choroid plexus vascular structure arising from the wall of each of the four ventricles of the brain. Produce cerebrospinal fluid. (shock absorber) Branching system of blood vessels running in fronds composed of collagenous tissue covered by cuboidal / columnar epithelium. Epithelial cells rest on a basement membrane. (When compared to ependymal cells, which have no basement membrane - unlike other epithelia) Central grey matter comprising Ventral horn - cell bodies of motor neurons Dorsal horn - cell bodies of smaller sensory neurons Central canal is lined by the ependymal cells and contains CSF (cerebrospinal fluid) White matter consists of ascening tracts of sensory neurons and descending motor neurons DS = dorolateral sulcus FC = fasciculus cuneatus FG = fasciculus gracilis

Salivary Glands

Parotid Submandibular Sublingual Numerous minor accessory glands scattered throughout the oral mucosa. Two main types of secretory cells are found: -serous cells -mucous cells

Autonomic Nervous system

Part of the PNS that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. Sympathetic and parasympathetic is part of the ANS. In the sympathetic the nerves originate in the lumbar and thoracic regions and mediate involuntary responses. In the parasympathetic system, the nerves originate in the midbrain, hindbrain and the sacral region. Functions include constriction of pupils, slowing heartbeat and stimulation of digestive glands. The difference between the symp, and the parasymp. lies in the fact that they are often opposite to one another. - ergo - stimulation by the parasymp. decreases the contractions of the heart, while the sympathetic does the opposite.

Uterus

Pear shaped organ about 7cm long Inner lining = Endometrium, changes during menstrual cycle. Endometrium: Consists of two layers: functionalis and basalis. Functionalis is sloughed at the time of menstruation; Basalis contains all of the elements that will restore the endometrium to prepare it for implantation. At end of menstruation a thin basalis layer remains. Over 14 days under the influence of oestrogen this thickens through an increase in glands and stroma. As oestrogen and progesterone levels decrease, the endometrium undergoes involution. Secretory phase of endometrium. After ovulation, under influence of Progesterone glands are stimulated to secrete glycogen, needed for nutrition of the fertilised ovum. Days 25-26 of the menstrual cycle, endothelin and thromboxin begin to mediate vasoconstriction of the spiral arteries. The resulting ischemia may cause some early menstrual cramps. By day 28 of the menstrual cycle, intense vasoconstriction and subsequent ischemia cause mass apoptosis of the functionalis. Menstrual phase begins as the spiral arteries rupture secondary to ischemia, releasing blood into the uterus. Apoptosed endometrium is sloughed off and usually lasts four days. During this period, the functionalis is completely shed. Arterial and venous blood, remnants of endometrial stroma and glands, leukocytes, and red blood cells are all present in the menstrual flow.

Peripheral nervous Tissues

Peripheral nerve Nerve fibres surrounded by - Endoneurium. These form bundles called Fascicles. These Fascicles are surrounded by Perineurium. All fascicles are bound by Epineurium.

Elastic cartilage

Picture showing the layers of elastic cartilage in ear. . . . . . . . . .

Breast Histology during Pregnancy and Lactation

Pregnancy - Oestrogen, Progesterone and Prolactin cause marked increase in numbers of acini Lactation - Oestrogen and Progesterone levels fall. Prolactin stimulates secretion of milk and oxytocin causes contraction of myoepithelial cells propelling the milk into the sinuses

Bone

Primary tissue of bone - Osseous tissue. Relatively hard and lightweight composite material, formed most of calcium phosphate and calcium hydroxylapatite. (Ca10(PO4)6(OH)2) Relatively high compressive strength, but poor tensile strength. Although bone is essentially brittle, it does have a significant degree of elasticity, contributed chiefly by collagen. All bones consists of living a dead cells, embedded in the mineralised organic matrix that makes up the osseous tissue.

Cells derived from the Mesenchyme

Primitive Mesenchymal cells are embryonic tissue from which all connective tissue is derived. They are stellate shaped with delicate branching cytoplasmic extensions. Oval nuclei. / E.C. matrix is mainly ground substance, with very few fibres - Permits free diffusion. These cells are derived from the mesenchyme: Fibroblasts: most common cells - responsible for secreting extracellular matrix. Myofibroblasts: contractile function + secretion of extracellular matrix. Chondrocytes / Osteocytes: responsible for secreting extracellular matrix in cartilage and bone respectively. Adipocytes: highly specialised for the storage and metabolism of fat, may collectively form adipose tissue. Defence and Immune cells: mast cells, tissue macrophages, and plasma cells; may be static or migrating elsewhere.

Small intestine

Principal site for absorption of digestion products. Anatomy reflects this funciton. Mucosa and submucosa are structured in folds ->plicae circulares Finger-like projections. Microvilli on the enterocytes. Prominent feature are 200+ lymphoid aggregations within lamina propria known as Peyer's patches. Groups of lymphoid follicles which bulge 'dome-like' into the lumen. Least in duodenum, most prominent in terminal ileum. Germinal centre of proliferating and maturing B cells surrounded by a mantle of small resting lymphocytes. Area between follicles consists of T lymphocytes. Epithelium overlying these 'domes' is specialised for antigen uptake. Three parts: Duodenum - 25-30cm Jejunum - 2.5 m Ileum - 3.5 m Circular folds - plicae circulares (valves of Kerckring) are particularly prevalent in the jejunum.

Prostate gland

Produces prostatic fluid and stores it for expulsion during ejaculation. Surrounded by fibro-elastic capsule rich in smooth muscle. Fibro-muscular stroma and bilayered ducts and acini. Acid phosphatase activity. Corpora amylacea ~ They are derived from degenerate cells or thickened secretions and occur more frequently with advancing age.

Basic forms in the GI tract

Protective: oral cavity, pharynx, oesophagus, anal canal. - stratified squamous epithelium. Secretory: only in stomach Absorptive: small intestine (duodenum / Brunner's glands) Absorptive / Protective: the whole large intestine, contains a lot of mucus-secreting cells.

Rectum and Anus

Rectum - dilated distal part of large bowel. Rectal mucosa similar to rest of large bowel with more goblet cells. Recto-Anal junction: abrupt transition to stratified squamous epithelium. Anal canal = last 2-3cm of GI tract, stratified squamous epithelium, gradual transition to skin. Anal canal is surrounded by skeletal muscle: anal sphincter.

Auerbach's plexus

Regulation of peristaltic contractions by nerve fibres located between circular and longitudinal layers of muscle.

Respiratory Mucosa

Respiratory epithelium: Pseudostratified columnar ciliated. Underlying lamina propria contains: Blood vessels. Serous and Mucous glands. This type of epithelium, which contains goblet cells begins near the base of the posterior surface of the epiglottis and lines most of the remainder of the larynx. It lines the false vocal folds, but not the true vocal folds. (diagram to aid)

Lower GI

Review on basic layering Epithelium Lamina Propria Muscularis Propria Submucosa Inner circular layer Outer longitudinal layer Serosa

Diffuse Neuroendocrine system

Scattered neuroendocrine cells G.I. system Secretion include gastrin, secretin, somatostatin and Vasoactive intestinal peptide (VIP) Respiratory system Secretions include serotonin, calcitonin, bombesin. Act in endocrine or paracrine fashion.

Intralobular / Intercalated ducts

Size of lumen Height of cell Simple Cuboidal in smaller ducts Stratified Cuboidal in larger ducts Amount of connective tissue around duct increases with duct size Intralobular larger Intercalated Ducts smaller

Skeletal Muscular tissue

Skeletal muscle - Striated - voluntary Responsible for movement of skeleton and organs like tongue. Arrangement of contractile proteins gives appearance of cross-striations on light microscopy; therefore striated muscle. Highly specialised cell, therefore cytoplasm = sarcoplasm. endoplasmic reticulum = sarcoplasmic reticulum. Each fibre is elongated, unbranched and cylindrical, numerous flattened nuclei are located at regular intervals just underneath the plasma membrane (sarcolemme) Composed of elongated multinucleate contractile cells, muscle fibres, bound together by collagenous supporting tissue.Individual fibres vary greatly in diameter. They are also grouped together in fasiciculi with delicate supporting tissue called endomysium between them. Each fascicle is surrounded by loose support tissue called perimysium. Most muscles are made up of many fasiciculi and they are all invested in a dense collagenous sheath called the epimysium. Large vessels and nerves enter the epimysium and divide and spread throughout the muscle in the peri- and endomysium. Small fasiciculi and lots of perimysium = muscles involved in fine controlled movements - eye. Large fasiciculi = muscles involved in gross movements. - butt Skeletal muscle contraction is controlled largely by large motor nerves. A group of muscle fibres supplying the same nerve = motor unit. When the nerve fires, all the fibres in a motor unit contract simultaneously. Vitality of skeletal muscle fibres is dependent on their nerve supply, so if the supply is damaged, the muscle fibres atrophy.

Parathyroid gland

Small (2-5mm glands) closely related to the posterior surface of the thyroid. Two pairs in most people Major role is secretion of PTH, which increases blood calcium levels. Three major actions: Bone: Increases osteoclastic resorption. Kidney: enhances renal tubular resorption of calcium. Small intestine: Vit D. dependent increase in calcium absorption. Two cell types present: Principal / Chief cells - small dark nuclei / pale cytoplasm. most numerous. Secrete PTH Oxyphil cells - abundant pink cytoplasm. not known to have secretory role.

Smooth muscle

Smooth - involuntary Arrangement of contractile proteins does not appear as cross-striations. Muscular component of visceral structures. (e.g. blood vessels, uterus, gall bladder, GI tract and bladder also called visceral muscle) Under inherent autonomic and hormonal control, so called involuntary muscle. Specialises in continuous contractions of relatively low force, producing diffuse wave-like rhythmic movements. Cells are relatively small, only a single nucleus. Fibres are bound together in irregularly branching fasciculi, differing from organ to organ, which form the functional contractile units. Fibres are elongated spindle-shaped cells, with tapered ends. Nucleus is centrally located.

Synapses and Neuromuscular junction (NMJ)

Specialised junction between neurons, or with neuron and effector cell. Axon of one neuron synapses with dendrite. Space between adjacent cleft = synaptic cleft. (20-30nm wide) Axon generating stimulus terminates at bulbous swelling = terminal button (not myelinated) Many types of neurotransmitters - acetylcholine, noradrenaline, glutamate, dopamine. A NMJ is the synapse or junction of the axon terminal of a motor-neuron with the motor end plate. The motor end plate is a highly excitable region of muscle fibre plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract. In vertebrates, the signal passes through the NMJ via the neurotransm. acetylcholine. 1 Motor Neuron may innervate from a few to more than a thousand muscle fibers. They occupy recess in muscle cell surface = sole plate. - Covered by extension of last Schwann cell. Post-synaptic membrane of neuromuscular junction is deeply folded to form parallel secondary synaptic clefts. - Transmitter is acetylcholine. Drawing of a Motor End plate . . . . . . . . . . Myasthenia Gravis - disorder of neuromuscular transmission, characterised by weakness and fatigability of skeletal muscles.

Spermatogenesis

Spermatogonia - primitive germ cells. Present only in small numbers in the male gonads before sexual maturity. After puberty, spermatogonia multiply continuously by mitosis to provide a supply of cells, which then undergo meiosis to form male gametes. The development of the spermatogonia into motile spermatozoa / sperm. Final maturation of spermatozoa occurs in the epididymis. Spermatogonia basally located (i.e. at periphery of the tubule.) Densely stained, round nuclei, diploid cells. Sit in the basal compartment created by Sertoli cells. Primary spermatocytes are the initial product of spermatogonial maturation. Large cells with a round nucleus filled with clumped chromatin material. After first meiotic division, they become secondary spermatocytes (seldom seen because they undergo second meiotic division) Secondary spermatocytes - meiosis - spermatids. Spermatids close to final morphological differentiation. Located closer to the lumen of the tube, resting in the branches of the Sertoli cell "tree". Spermatids virtually completed spermiogenesis. Ready to be cast off into the lumen. Cast off cytoplasmic droplets are below them. Beneath the maturing sperm, another wave of spermatids is beginning the process of differentiation. DRAWING OF THIS MIGHT BE POTENTIALLY REALLY HELPFUL IN TRIMMING FAT.

Four functional components of the Male reproductive system

Testes - produces male gametes / secretes testosterone. Ductular system - collect, store, conduct spermatozoa from testes. Exocrine glands - produce seminal fluid Penis - organ of copulation Anatomical location of Male reprod. . . . . . . . . . . . .

Basic Periodic Acid Schiff (PAS)

Stains complex carbohydrates deep red eg. basement membranes Also stains stored glycogen, but digested on enzyme treatment diastase (PAS-D)

Gastric Glands / Cell types

Stem cells: Are found in the isthmus and neck. High rate of mitosis. Some move upward to replace mucous cells (4-7 days turnover period) Others migrate downwards to differentiate into parietal, chief and endocrine cells. Mucous neck cells: Are present in clusters or single cells in the necks of gastric glands. Their secreiton is quite different (larger secretory granules) from the superficial mucous glands. Parietal (oxyntic) cells: Present mainly in the upper half of the gastric glands, large round cells with eosinophilic cytoplasm. Secrete HCl, and intrinsic factor, which is crucial for Vit B12 absorption. The most striking feature of active parietal cells is the presence of numerous mitochondria and intracellular canaliculi. They also have large, rounded eosinophilic cytoplasm, with a central nucleus. In the resting cells, there are tubovesicular structures. Chief (zymogenic) cells: They predominate in the lower part of the tubular glands. They have abundant rER, condensed basal nuclei, basophilic granular cytoplasm. They secrete pepsinogen. (inactive enzyme) Pepsinogen rapidly converts into the active form: pepsin. Pepsin is a proteolytic enzyme. Chief cells also secrete lipase. Neuroendocrine cells / argentaffin: Are found in the necks and base of gastric glands. In the fundus, 5-hydroxytryptamine (serotonin) is one of the principal secretory products. These are very hard to see. Most pick up silver -> argent. They secrete hormone. Chief cells - > dark staining Parietal cells - >light stained

Layers of the epidermis

Stratum basale: Repeated mitotic division leading to regeneration. (Human epidermis renews every 15-30 days) Stratum Spinosum: aka prickle cell layer: Large pale nuclei, prominent nucleoli. Intercellular bridges are tonofilaments. Stratum granulosum: Coarse basophilic keratohyaline granules. Together, the granulosum and the spinosum are referred to as the Malphigian layer. Stratum corneum: aka keratin layer: 15-20 layers of flattened, non-nucleated keratin material. In addition, the stratum lucidum is a thin layer of translucent cells seen in only thick epidermis. (not in thin) It represents a transition from the stratum granulosum and stratum corneum.

Lymph nodes

Structure: Small, bean-shaped organs situated on the coarse of lymphatics so lymph draining back to bloodstream passes through one or more lymph nodes. In inactive state only a few mm in size. Lymph nodes are surrounded by a collagenous capsule, from which trabeculae extend for a variable distance into the node. Mature lymph nodes are distributed throughout the body in aggregates. Encapsulated and highly organised, present along the larger regional vessels of the lymphovascular system. Occurs in groups: especially neck, axillae, groins, lung hila and para-aortic areas. Functions: Non-specific filtration of particulate matter and micro-organisms from lymph. Interaction and circulating lymphocytes with antigen-containing lymph. Activation and proliferation of B cells. Aggregation, activation and proliferation of T cells. Cell types present: Lymphoid cells Immunological accessory cells Stromal cells

The Sublingual Gland

Sublingual glands are mainly mucous, viscid secretion. The secretion produced is mainly mucous in nature, however it is categorized as a mixed gland. Unlike the other two major glands, the ductal system of the sublingual glands do not have striated ducts, and exit from 8-20 excretory ducts. Approximately 5% of saliva entering the oral cavity come from these glands

Dermis

Supports the epidermis via anchoring fibrils and connects it to the hypodermis (sub-cutaneous tissue). Anchoring fibrils attach dermis to epidermis. Surface of the dermis is irregular: dermal papillae -> interdigitate with epidermis at epidermal pegs or ridges. The dermis also contains loose connective tissue. Fibroblasts, mast cells and macrophages and leukocytes are present, as well as: Blood vessels, lymphatics, nerve endings, eccrine and apocrine sweat glands.

Ganglia

Sympathetic Ganglion cells (still part of the ANS) are multipolar, more widely spaced. Nuclei tend to be eccentrically located. Cytoplasm has variable quantities of lipofuscin. Lipofuscin - finely granular yellow-brown pigment granules, composed of lipid-containing residues of lysosomal digestion. It is considered one of the aging pigments, found in the liver, kidney, heart muscle, adrenals, nerve cells and ganglion cells. It is arranged around the nucleus. Autonomic ganglia may actually be embedded in the substance of a visceral organ, in which case they are called "terminal ganglion"

T lymphocytes

T helper cells: help other lymphocytes perform functions. Cytotoxic T cells: kill virally infected and malignant cells. Suppressor T cells: switch off the immune system when the stimulating antigen is removed. Three consequences of T cells recognising antigenic peptides presented by MHC molecules on antigen-presenting cells. Drawings representing the 3 paths . . . . . . . . . . . . .

Salivary ductal system

Terminal secretory units merge to form intercalated ducts. Intercalated ducts are lined by cuboidal secretory cells. Intercalated ducts join to form intralobular ducts, also called striated ducts because infoldings of the basal membranes of their lining cells give the appearance of radial striations from the base to the nuclei of the cells. The striations are due to interdigitating cytoplasmic processes of adjacent lining cells, which contain many mitochondria needed to provide energy for ion transport. These ducts join to form the main duct of each gland, lined by stratified, non-keratininized, squamous epithelium, like the oral cavity into which they empty.

Thymic histology

The epithelial cells provide a mechanical framework. Cortical epithelial cells ("nurse cells") envelope multiple lymphocytes promoting T cell differentiation and proliferation. Hassall's corpuscle: eosinophilic structures in the centre of the medulla formed by groups of keratinised epithelial cells (probably degenerative) -> function uncertain Also an APC called a thymic interdigitating cell. In adults, T-cell precursors enter the thymus at the cortico/medullary junction, and then begin a highly ordered differentiation programme, which is linked to migration through the thymic stroma. Different thymocyte subsets are found in spatially restricted regions of the thymus.

Ileocaecal junction

The ileocaecal junction separates the ileum from the large intestine. It can be seen as a transition from villous mucosal surface of the ileum to flat mucosa of large intestine. There is prominent submucosal adipose tissue characteristic of this region. transition between small int. and large int. . . . . . . . . . .

Lymphoreticular Introduction

The immune system provides highly specific responses to antigen with destruction of the antigen. (from antibody generator) - originally defined as any molecule that binds specifically to an antibody, the term now also refers to any molecule or molecular fragment that can be bound by a major histocompatibility complex (MHC) and presented to a T-cell receptor. Numerous cells are involved and these reside in several organs.

Meninges

The meninges (singular meninx) is the system of membranees which envelops the CNS. The meninges consists of three layers: dura mater / arachnoid mater and pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system. Representation of layers . . . . . . . . . . . Pia mater - surface of nervous tissue delicate, contains collagen fibres, fine elastin fibres and occasional fibroblasts. Arachnoid mater - Cobweb-like strands connect it to the pia mater. Space between these layers = sub arachnoid space, in places forms large cisterns. CSF circulates from the ventricular system into subarachnoid space. Arteries and veins pass in subarachnoid space. Dura mater - outermost layer. Dense fibroelastic layer lined on internal surface by flattened cells. In the cranium, the dura merges with the periosteum; in the spinal canal, it is suspended by denticulate ligaments with epidural space filled with loose fibro fatty tissue.

Structure of the GI tract

The pattern is more or less the same throughout the GI tract. Mucosa: epithelium, lamina propria, muscularis mucosae (local movement and folding of the mucosa) Submucosa: nerves, blood vessels, supporting connective tissue. muscularis propria: two layers: outer longitudinal layer, and inner circular layer. Only in the stomach, a third, inner oblique layer is present. Adventitia: Outermost layer of loose supporting tissue within the abdominal cavity = serosa (visceral peritoneum) = simple squamous layer of mesothelium.

Epithelium of efferent ducts

The rete testis opens into seven or eight efferent ducts. Relatively short and highly coiled. Lined by pseudostratified columnar epithelium of peculiar appearance, varying in height from place to place, giving the duct a "scalloped" appearance. Many (but not all) of the epithelial cells lining the duct, especially the taller ones, are ciliated. These are true cilia capable of movement. The cilia help propel the spermatozoa.

Spermiogenesis

This process takes about 70 days. Both spermatogenesis and spermiogenesis (final stage) occur within the testes. Spermiogenesis - process by which spermatids are transformed into motile mature spermatozoa. During this process, the Golgi app. elaborates a large vesicle. = acrosomal vesicle. Accumulates carbohydrates and hydrolytic enzymes. This vesicle becomes applied to one pole of the progressively elongating nucleus. Forms acrosomal head cap. Meanwhile, both centrioles migrate to the end of the cell opposite to the acrosomal head cap. Centriole aligned parallel to the long axis of the nucleus elongates to form flagellum - basic structure similar to that of the cilium. As the flagellum elongates, nine coarse fibrils, (contain contractile proteins) arranged longitudinally around the core of the flagellum. Further rib-like fibrils then become disposed circumferentially around the whole flagellum. The cytoplasm migrates to surround the first part of the flagellum. The remainder of the flagellum appears to project from the cell but in fact remains surrounded by plasma membrane. This migration of cytoplasm thus concentrates mitochondria in the flagellar region. As the flagellum elongates, excess cytoplasm is phagocytosed by the enveloping Sertoli cell prior to release of the spermatid into the lumen.

Organs of the Lymphoid system

Thymus Lymph nodes Mucosa-associated lymphoid tissue (MALT) Spleen

Supporting tissues

Tissue of mesodermal origin - provides structural and metabolic support for other tissues and organs, while mediating exchange of nutrients, gases and metabolites between tissues and the circulatory system. Generally contains blood and lymphatic vessels. Supporting tissues are composed of: specialised cells E.C. Matrix - dominant component of many tissues, comprised of: ground substance, fibres. Physical properties of the tissue are determined by the E.C. matrix component. Wavy bundles of pink-stained material = fibrous proteins with a low cell density. Loose connective tissue is usually composed of fibroblasts, long cytoplasmic processes, this is rich in hyaluronic acid and fibres.

Main Bronchi

Trachea divides at the carina Forms two main bronchi, right and left Enter respective lungs Divide into smaller (segmental) bronchi Divide into bronchioles

Placenta

Trophoblast forms finger-like projections or chorionic villi that protrude into maternal vessels. It is through these "vessels" that the fetus and mother exchange materials. Placenta is a mass of such villi, connected to the fetus via the umbilical cord.

Lecture 1: Basic Tissue Fixation

Unfixed tissue will degrade by autolysis Fixative required to maintain structure: Either denatures proteins (e.g alcohol-based). OR cross-links proteins (e.g. formaldehyde) Formalin (37% formaldehyde) most common fixative.

Blood circulatory system

Tunica Intima: An inner lining composed of flattened epithelial cells, endothelium, supported by basement membrane and delicate collagenous tissue. Tunica media: Intermediate mainly muscular layer. Shows the variation of all the layers. Tunica adventitia: Outer supporting tissue layer. When considering the heart, there are 3 layers: Tunica Intima = Endocardium Tunica Media = Myocardium Tunica Adventitia = Epicardium or visceral pericardium. The tissues of thick walls of large vessels cannot sustain themselves by diffusion of nutrients from the lumina alone. Instead, they are supplied by vasa vasorum, which are small arteries running in the tunica adventitia.These send arterioles and capillaries into the tunica media .

Types of bone

Two types of bone can be identified microscopically according to the pattern of collagen forming the osteoid (collagenous support tissue of type I collagen embedded in glycosaminoglycan gel): 1) woven bone characterised by haphazard organisation of collagen fibres and is mechanically weak. 2) lamellar bone which has a regular parallel alignment of collagen into sheets (lamellae) and is mechanically strong. - Osteocytes embedded in lacunae. (lacunae are black holes in which osteocytes are embedded in.) - Cytoplasmic extensions of osteocytes link via canaliculi.

Small intestinal villi / crypts is lined by simple columnar epithelium

Variety of cells. Enterocytes - Most numerous, tall, columnar, surface microvilli. Goblet cells - produce mucin. Paneth cells - base of crypts, eosinophilic apical granules. Neuroendocrine cells - produce locally acting hormones. Stem Cells - base of crypts, divide to replenish above cell types. Intraepithelial lymphocytes. Neuroendocrine / APUD cells APUD - amine and precursor uptake and decarboxylation. They have eosinophilic granules, but they are sub-nuclear. A collective term for a diffuse range of endocrine cell types scattered throughout the body. APUD cells constitute a component of a universal diffuse neuroendocrine system. - histologically, these cells can be identified by their staining behaviour. (chromaffin argentaffin / chromophil cells)

Blood

Various cells suspended in plasma. Transports gases, nutrients, products of metabolism, cells and hormones. (Erythrocytes / Leukocytes / Thrombocytes : aka RBC / WBC / platelets. RBC / Erythrocytes: Major function is O2 and CO2 transport. Due to high haemoglobin content, (quaternary structure protein) cells stain pink. Main skeletal protein is spectrin. Reticulocytes - form in which erythrocytes are released from bone marrow. Immature RBCs retain residual nuclear material. Leukocytes / WBC - Granulocytes (granular): Neutrophils / Eosinophils / Basophils. Phagocytes: Neutrophil / Eosinophil / Monocyte / Macrophage. Mononuclear leucocytes (agranular) - lymphocytes (T cell and B cell) / monocytes

Exam revision

What type of epithelium lines the organ/structure? What does it secrete? How is it adapted for its function?

Epidermis:

What type of epithelium lines the organ/structure? Keratinising stratified squamous epithelium. Adapted to withstand constant abrasion and desiccation due to tough non-living surface layer composed of protein keratin wrapped in plasma membrane. (As the epithelium matures, nuclei are eventually lost). The epidermis is avascular, nourished by diffusion from the dermis. 95% of the epidermis is keratinocytes Rete ridges are epidermal thickenings that extend between dermal papillae. Layers of the epidermis: moving superiorly: Stratum basale, spinosum, granulosum, lucidum, corneum.

Secretory Cells - Serous

Zymogen granules contain enzymes, and stain strongly, apically. Nuclei are rounded with dispersed chromatin. Mucous cells - within these cells are poorly stained nuclei, which are characteristically flattened against the basement membrane.

Tendon

a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fascia as they are all made of collagen except that ligaments join one bone to another bone, and fascia connect muscles to other muscles. Tendons and muscles work together and can only exert a pulling force. Ligaments bind bone to bone. Tendons bind muscle to bone.