Reproductive TBL Quiz Histology
1. Describe the overall organization of the ovary: hilum, cortex, medulla
Medulla is in middle, cortex is outside, and hilum leaves the ovary towards the uterus.
1. Know the histology of the seminiferous tubules
- A distinct connective tissue capsule, a layer of flattened myoid cells, and a basement membranous surround seminiferous tubules. The SEMINIFEROUS EPITHELIUM is an unusual, complex, stratified epithelium with two cell populations: SPERMATOGENIC (or germ) CELLS and NONPROLIFERATIVE SERTOLI CELLS
1. Know the general organization and the histology of the testes: epididymis, vas deferens, tunica albuginea, mediastinum, rete testis, seminiferous tubules
- After spermatozoa are produced in the testes, they travel a long, tortuous routeL from seminiferous tubules to the paired RETE TESTIS, EFFERENT DUCTULES (ductuli efferenti), EPIDIDYMIS, DUCTS (VAS) DEFERENS, and EJACULATORY DUCTS, and to the single urethra and penis - The testis, an ovoid gland, is encased in a thick capsule fo dense fibroelastic connective tissue known as the TUNICA ALBUGINEA, because it appears white in life. An outer layer of the tunica vaginalis invests teh capsule externally. - Along the posterior border of the testis, the capsule projects inward as a thickened ridge, known as the MEDIASTINUM TESTIS. This ridge corresponds to the hilum of other glands - the site where ducts, blood vessels, lymphatics, and nerves connect to the gland interior - Thin fibrous partitions, or septa, radiate from teh mediastinum and form wedge-shaped lobules, about 250 in the humans. The lobules contain SEMINIFEROUS TUBULES, which are sectioned in different planes because they have a convoluted course.
2. Identify the peg and ciliated cells in the mucosa of the fallopian tube, and know their function
- CILIATED CELLS with spherical nuclei bear apical cilia that beat toward the uterus. The chief function of ciliary motility is transport of oocytes from upper to lower ends of the fallopian tubes. - The fewer nonciliated secretory cells are named PEG CELLS, because they bulge above the surface and appear to insert into the epithelium like pegs - During the proliferative phase, epithelial cells are tall and columnar, and ciliated cells predominate During the secretory phase, the epithelium is low columnar to cuboidal with high number of PEG CELLS, which synthesize and secrete glycoproteins to provide nutrients to oocytes. - Early in the follicular phase, estrogen stimulates synthetic activity of peg cells and ciliogenesis in ciliated cells. Both proliferation and functional activity of this epithelium are regulated by estrogen receptors and fallopian tube - specific transcription factors in the cells
3. Know the function of Sertoli cells; role of tight junctions between Sertoli cells 4. You do not need to be able to distinguish between germ cell at various stages of spermatogenesis
- During a transformation period, spermatids attach tot eh relatively new Sertoli cells, which are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. Spermatids, which are known as early and late, do not divide but mature into SPERMATOZOA, which are released into the lumen and carried into efferent ducts
1. Describe the histology of the uterine (fallopian) tube (oviduct)
- Fallopian tubes (oviducts, uterine tubes) extend from the ovary to the uterus. They are suspended by thin mesentary known as the MESOSALPINX, which is derived from the broad ligament. After ovulation, the fallopian tube receives the oocyte and provides a suitable environment for fertilization. It is also where the initial embryonic development normally occurs, for about 3 days before transport of the early embryo, or zygote, to the uterus. 1. The INFUNDIBULUM is the initial, open-ended, trumpet-shaped segment that bears fringed folds called FIMBRIA 2. The tube opens in to the peritoneal cavity, so it may allow infection to enter the abdomen. The most dilated part of the fallopian tube, which accounts for most of its length, is the AMPULLA. It has a thin wall with complex infoldings of mucosa. 3. The ampulla leads into the shortest, thick-walled segment known as the ISTHMUS, which connects to the uterus. 4. The last part, which passes through the uterine wall, is the INTRAMURAL, or UTERINE, PART. Consists of an inner MUCOSA, MUSCULARIS, and external SEROSA
2. Distinguish the spermatogenic (germ) cells from the Sertoli cells
- In a seminiferous tubule, germ cells are at various stages of spermatogenesis. The cells closest tot eh basement membrane with spherical nuclei are SPERMATOGONIA. The haploid secondary spermatocytes are seldom seen; almost as soon as they form they divide and produce SPERMATIDS
2. Recognize the rete testis in the mediastinum
- In the mediastinum, seminiferous tubules empty into TUBULI RECTI and RETE TESTIS, which coalesce to form six to eight (6-8) EFFERENT DUCTULES. These ducts drain testicular fluid and spermatozoa to the proximal part of the EPIDIDYMIS. The rete testis is a labyrinthine network of collecting chambers of simple cuboidal epithelium. Interstitial connective tissue constitutes 20-30% of the substance of the gland and consists fo vascularized connective tissue with clusters of hormone-producing LEYDIG CELLS
1. Recognize and describe the histology of the placenta
- Placenta is a transitory compositive structure with both FETAL and MATURE components. It develops in pregnancy in close association with uterine endometrium. - The maternal component of the placenta is the DECIDUA BASALIS of the endometrium, which is the modified stratum basale in which the embryo is implanted. The fetal component, formed from teh chorionic sac surrounding the embryo, consists of the chorionic plate and its branching chorionic villi that extend from the chorion like branches of a tree - Fetal blood and maternal blood are close to each other but follow independent courses and do not mix, being separated by an efficient placental barrier - CHORIONIC VILLI are the fundamental units of the placenta! Each villus is formed from two epithelial cell layers derived from the trophoblast of the embryo, which are closely associated with extra-embryonic connective tissue. - An inner single layer of CYTOTROPHOBLASTS, or LANGHANS CELLS, consists of cuboidal epithelial cells with light-staining cytoplasm and distinct cell boundaries. They give rise to a continuous superficial layer of larger SYNCIOTROPHOBLASTS, which stain darker and have ill-defined cell boundaries - Macrophages known as HOFBAUR CELLS, are also present in villi and become more numerous during gestation. In the second half of pregnancy, cytotrophoblasts gradually disappear, and a thin layer of multinucleated syncytiotrophoblasts remains on villi surfaces. In the third trimester, local bulges of syncytiotrophoblast nuclei, called syncytial knows, are common. Fetal capillaries in the stroma of each villus receive blood from umbilical arteries and drain into venules that deliver blood to umbilical veins
3. Recognize Leydig cells
- Produce testosterone in the presence of luteinizing hormone (LH)
1. Describe the histology of the cervical-vaginal junction (endocervix, transformation zone, exocervix; associated glands)
- The cervix is the inferior, cylindrical tapering end of the uterus that consists of two anatomic regions: - The upper part- the CERVICAL CANAL - begins at the uterine isthmus. It extends downward into the upper part of the vagina, known as the PORTIO VAGINALIS - The cervical canal is lined by mucous membrane known as ENDOCERVIX. The endocervix is lined by mucus-secreting simple columnar epithelium that is arranged as deep compound furrows. - The portiovaginalis is lined by the exocervix - An abrupt change in the epithelium occurs at the EXTERNAL OS - from simple columnar to nonkeratinized stratified squamous. This area, known as the TRANSFORMATION ZONE, is subject to tumor formation and is the site fo most cervical carcinomas.
2. Recognize the histology, and identify the cells, of the corpus luteum and corpus albicans
- The corpus luteum, is a large endocrine structure formed from the remains of the large dominant follicle after it undergoes ovulation. Granulosa lutein cells undergo significant hypertrophy, producing most of the corpus luteum's increased size, and begin producing progesterone. The theca lutein cells increase only slightly in size, are somewhat darker-staining that the granulosa cells, and continue to produce estrogens. Theca lutein cells derived from the theca interna are typically located within the folds that comprise the bulk of this tissue - Corpus albicans is the scar of conenctive tissue that forms at teh site of a corpus luteum after its involution. It contains mostly collagen, with few fibroblasts or other cells, and gradually becomes very small and lost in the ovarian stroma. Involution of the corpus luteum does not involve atresia.
1. Know the general organization and the histology of the male genital ducts: epididymis and vas (ductus) deferens
- The epididymis caps teh posterior part of each TESTIS, its main component being tightly packed tortuous duct. The epididymis, derived from the mesonephros int he embryo, is divided into three parts: an initial (head) segment, a body (the main part of the duct), and a caudal (tail) region - The head consists of tightly coiled parts of efferent ductules. Several cross and oblique views of the same duct are usually seen in histologic sections. In 25% males, the head contains a pedunculated cystic structure, the appendix epididymis, which is believed to be an embryologic remnant - Wall of duct of the epididymis consists of very highly pseudostratified epithelium containing basal (stem) cells and tall columnar (principal) cells with long, apical, nonmotile stereocilia projecting into the lumen - The ductus deferens, a continuation of the epididymis, is a hollow tube. It ends in the excretory duct of the SEMINAL VESICLE to form the ejaculatory duct, which passes through the prostate to drain into the prostatic part of the urethra. It derives embryologically from the mesonephric (wolffian) duct. Pseudostratified columnar epithelium, composed fo columnar cells and basal cells, lines the tube - Underlying LAMINA PROPRIA is rich in elastic fibers. The wall has a thick three-layer smooth muscle coat and an inner mucosa in longitudinal folds. COnsists fo a prominent middle circular layer enclosed by thinner inner and outer longitudinal layers. The outermost adventitia is loose connective tissue containing blood vessels and nerves, which blend with surrounding tissue. Via sympathetic stimulation, smooth muscle contraction force spermatozoa along the duct during ejaculation
1. Describe the organization and histology of the uterus: fundus, corpus (body), cervix
- The expanded, upper part of the organ is the body, or CORPUS - Fallopian tubes enter the wall the most superior, dome-shaped region, called the FUNDUS - At the narrowest and most inferior part of the organ, the CERVIX opens into the vagina The corpus and fundus are almost identical histologically, but the cervix shows some important structural difference. The three layers of the uterus include the outer PERIMETRIUM (mainly connective tissue that is only partly covered in some areas by peritoneal mesothelium constituting a serosa), the intermediate and thickest layer, the MYOMETRIUM (consisting of interconnecting bundles of smooth muscle separated by connective tissue), and the innermost ENDOMETRIUM (is a specialized mucosa consisting of simple and columnar epithelium, which undergoes pronounced cyclic changes during the menstrual cycle)
2. Describe the histology of the vagina
- The vagina is a distensible fibromuscular tube that connects the cervix of the uterus to the exterior of the body. Its wall has three layers: MUCOSA, MUSCULARIS, and ADVENTITIA - The mucosa consists fo prominent nonkeratinized stratified squamous epithelium, and an underlying LAMINA PROPIA - Vagina has no glands and gets its mucus for surface lubrication from the mucous glands in the cervix. The transverse folds, or RUGAE, of the mucosa are prominent in teh relaxed vagina. Near time of ovulation, estrogen stimulates an increased glycogen count. When the cells are shed, they discharge glycogen into vaginal lumen - With diminished estrogen levels after menopause, the vaginal epithelium atrophies with a dramatic reduction in the number of stratified layers
1. Recognize and describe the transformation of the post-ovulation follicle
After the Graafian follicle has ruptured at ovulation and teh secondary oocyte is released, a temporary glandular structure - the CORPUS LUTEUM - forms in teh follicular remnant. The follicle collapses a nd becomes highly infolded, and its lumen fills with fibrin-containing fluid and blood.Coagulation of teh enteral space forms a clot that is replaced by fibrous scar tissue. The basement membrane separating GRANULOSA CELLS from THECA INTERNA CELLS is broken down, and vascular invasion of the formerly avascular granulosa layer results. Luteinizing hormone from the anterior pituitary influences both granulosa and theca interna cells to change into GRANULOSA LUTEIN and THECA LUTEIN CELLS respectively. Their cytoplasm accumulates lipid droplets and it is slightly eosinophilic. - Granulosa lutein cells synthesize and secrete the hormone progesterone, which prepares the endometrium for implantation of a fertilized ovum and stimulates growth of mmary glands. - Theca lutein cells synthesize and secrete estrogen. If pregnancy occurs, the corpus luteum persists for the first 8 weeks, after which the placenta becomes the major site for steroid hormone production. If pregnancy does not occur, the corpus luteum gradually involutes, stops producing progesterone, and forms a white scar called the CORPUS ALBICANS, or white body
2. Recognize atretic follicles
Atresia or degeneration of a follicle. Characterized by apoptosis of follicle or granulosa cells and autolysis of the oocyte, with the macrophages entering the degenerating structure to clean up debris
1. Recognize and describe the histology the developing follicles (from primordial to mature)
Follicular epithelium forms a solid SECONDARY FOLLICLE in which mitotically active GRANULOSA CELLs become stratified and form several layers of concentrically arranged, closely packed cells. The primary oocyte diameter increases, and the extracellular layer, the ZONA PELLUCIDA (rich in proteoglycans), surrounds the cell's plasma membrane As the follicle enlarges adn consists of 8-12 layers of granulosa cells, small, irregular fluid-filled spaces develop among the cells, and the follicle is called a SECONDARY (vesicular, or antral) FOLLICLE. Eventually large enough the spaces coalesce to form a single cavity known as the FOLLICULAR ANTRUM. Inside is a clear, viscous fluid within the antrum known as the liquor folliculi (rich in hyaluronic acid, growth factors, and steroid hormones produced by granulosa cells) THECA INTERNA cells become vascularized and secrete the steroid androstenedione, from which granuloma cells produce estrogens. An outer layer of these THECA EXTERNA cells also form and is continuous with connective tissue cells of the stroma
2. Describe the histology of the endometrium during the menstrual cycle
The endometrium has a unique and dual blood supply and consists of two functional layers: - The thicker, more superficial FUNCTIONALIS layer is most affected by menstruation. It is periodically shed. - A deeper basal layer, the STRATUM BASALE, is unaffected by hormonal variations, it continues to aid the superficial layer regeneration without being sloughed off itself during menstruation. - The uterine artery distributes blood to 6-10 arcuate arteries, which encircle the UTERUS just beneath the SEROSA. They in turn give off radial arteries hat penetrate inward to the inner muscular layer of the myometrium and five off two distinct sets of arteries, known as basal and spiral arteries. Short, straight basal arteries supply the stratum basale and maintain uninterrupted circulation. - In contrast, spiral (coiled) arteries pass through the statum basale, run parallel with uterine glands and reach the endometrial surface. They drain into an extensive capillary network, which ramifies into thin-walled venous lakes that drain into efferent veins. The distal segment of spiral arteries degenerates and regenerates with each menstrual cycle. About 1 day before menstruation, intense vasoconstriction of these arteries produces ischemia and rupture of the capillaries that they supply. Uterine glands undergo necrosis; blood, uterine secretions, and tissue debris are sloughed off from the endometrium and discharged through the vagina The ENDOMETRIUM and OVARIES undergo cyclic changes resulting from interplay of hormones produced by the PITUITARY, OVARIAN FOLLICLES, and CORPUS LUTEUM. Phases in cycle are MENSTRUAL (days 1-4); FOLLICULAR, or PROLIFERATIVE (days 4-15); LUTEAL, or SECRETORY (days 15-27); and PREMENSTRUAL, or ISCHEMIC (day 28) - The pituitary contributes follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin; ovaries, estrogen, and progesterone respectively
