Epithelium and Glands 8/17
____ connexins = ___________
6 connexins = 1 gap junction
what are microvili and what are they composed of
Apical hair-like projections composed of cross linked actin filaments
what is GMS and what does it stain? what color?
GMS = grocott methenamine silver stains type III collagen, fungus and other microbes black
what is PAS and what does it stain? what color
PAS = Periodic acid Schiff stains mucopolysaccharides (protein that makes up basement membrane) and glycogen/other carbs magenta
what happens in a merocrine secretion
The product is released from an exocrine cell by membrane-bound secretory vesicles through exocytosis. Vesicles will fuse to plasma membrane in apical surface for exocytosis
What is AFB and what does it stain? what color?
Ziehl-Neelsen acid-fast bacilli stain stains bacteria such as the bacteria causing TB stains purple
What is transitional epithelium?
a specialized type of stratified epithelium with the ability to contract and expand
what are the functions of simple cuboidal tissue?
absorption secretion active ion transport
what are the functions of simple columnar cells
absorption and secretion
what parts of the body are derived from the endoderm of the embryo
alimentary tract GI tract respiratory tract liver pancreas endocrine glands
what are stereocilia and what are they composed of
apical hair like projections composed of actin longer than microvilli
what are cilia and what is their arrangement/what are they composed of
apical projections made of tubulin tubules arranged in 9 +2 orientation
what are the three surfaces of an epithelial cell
apical, lateral, basal
what are characteristics of pseudostratified columnar (shape, nuclei, components)
appears multilayered but only a single layer columnar shape variable nuclear position ciliated intermixed with mucous-secreting goblet cells
what are some features of stratified squamous epithelium
avascular and variable in thickness multiple layers of squamous cells layering over the basement membrane
what is the epithelial function of the skin?
barrier protection, thermoregulation, sweat, synthesis of vitamin D
what does hematoxylin bind to and what does it stain?
binds to DNA and RNA stains nucleic acids blue
what is wright's stain commonly used for
blood cells
how do epithelial tissues form/ what are they derived from?
brachial arches
what drives polarity in epithelial tissue
cell junctions - protein complexes that bind cells together
what takes place at the lateral surfaces of an epithelial cell
cell-cell adhesion and communication
what takes place at the basal surface of an epithelial cell
cell-extracellular matrix adhesion to the basement membrane
what characteristic do surface cells on transitional epithelium share
cells are rounded
how does cilia differ in composition compared to sterocilia and microvilli
cilia is made of tubulin and stereocilia and microvilli are made of actin
what are multicellular glands and how are they categorized
collection of cells that together produce secretion categorized in single and compound glands
what is trichrome stain commonly used for
connective tissue
what is the role of the basement membrane?
connects all epithelium to connective tissue
what does the ectoderm layer do?
cover the external surface of brachial arch
what is the shape and nuclei location of simple cuboidal
cube shaped cells central nucleus
what do gap junctions connect and what does it allow?
cytoplasm of adjacent cells allows for direct passage of small molecules between cells
connective tissue is ______ in relation to epithelium
deep/ under
what makes up anchoring junctions
desmosomes and hemidesmosomes
what is cell polarity
different sides of epithelial cells express different components and thus have different functions
what are the three layers of a brachial arch?
ectoderm, mesoderm, endoderm
what is stained with weigert's elastic stain and what color?
elastic fiber- blue/black
what is weigert's elastic stain used for
elastic fibers
what does eosin bind to and what does it stain?
eosin binds to cytoplasmic elements and stains them pink-red (specifically stains elastic and reticular fibers in cytoplasm pink)
what are the 4 main tissue types
epithelium connective tissue muscle nervous
what parts of the body are derived from ectoderm
epithelium of the mouth, nose, paranasal sinuses, part of pharynx epidermis hair nails prepuce of genital organs lens of eye cornea tooth enamel anal canal adrenal medulla
what is the difference between an exocrine gland and endocrine gland?
exocrine glands produce secretions that exit onto epithelial surfaces endocrine glands produce secretions that enter into bloodstream
what is the shape and nuclei location of simple squamous cells
flattened, pillow shaped cells central nucleus
what does the mesoderm do?
forms the core of each brachial arch
what is toluidine blue commonly used for? (metachromatic stain)
general staining
what is hemotoxylin commonly used for?
general staining with eosin
what is eosin commonly used for?
general staining with hematoxylin
Where can simple cuboidal epithelium be found?
glandular ducts, kidney tubules, thyroid follicles, lung, kidney, salivary gland
what is a unicellular exocrine gland
goblet cell- single secretory cells are distributed among non-secretory cells and able to release secretory product
if you are trying to see whether your tissue sample has viable nuclei what stain would you use?
hematoxylin
what are the four types of stains used to see structures within tissue?
hematoxylin eosin trichrome verhoeff-van gieson
what are cytokeratins and what are the produced by
intermediate filament proteins produced by all epithelial cells
how do tight junctions determine and maintain polarity
junctions are impermeable to water and solutes (no paracellular transport) forces cells to actively pump nutrients (transcellular pathway) *once a cell is bound with tight junction, nothing can pass through
what parts of the body are derived from the mesoderm of the embryo
kidneys and ureters adrenal cortex gonads and genital ducts endothelium of blood/lymphatic vessels mesothelium
what is the difference between light and electron microscopy
light microscopy allows for a magnification in 2D view electron microscopy allows for vision of ultra structure in 3D view
what does the endoderm do?
lines internal surfaces of brachial arch
Where can pseudostratified columnar epithelium be found?
lines the respiratory tract
where can simple columnar cells be found
lining the stomach and intestines ameloblasts (beginning of tooth formation)
where can apocrine secretions be found
lipid droplets incorporated into breast milk
what is the function of certain epithelial tissue dependent on
location and organ
what does toluidine blue stain and what color?
mast cell granules and glycogen stains purple
what are the three types of secretions from exocrine glands
merocrine apocrine holocrine
what is the most common exocrine secretion?
merocrine secretion
what is the least common source of epithelium that is embryonically derived
mesodermal
Where can simple squamous epithelium be found?
mesothelium and endothelium
what is histology?
microscopic study of tissue structure
what are the three components that can be found on the apical surface of an epithelial cell
microvilli stereocilia cilia
what color does wright's stain present as?
neutrophil granules - purple/pink eosinophil granules - bright red/orange basophil granules - deep purple/violet platelet granules - red/purple
what is the basement membrane composed of?
non-cellular structure -protein and polysaccharide rich
what is the epithelial function of the intestines and kidneys?
nutrient absorption from digestion
how many layers does simple epithelium have
one
what are tissues?
organized aggregates of cells that function in collective and coordinated manner
what is the function of simple squamous tissue?
oxygen exchange CO2 exchange protective barrier
where can merocrine secretion be found
pancreas, salivary glands
all diseases have _____
pathological basis
what is the mesothelium of the heart called
pericardium
what is the mesothelium of the abdominal region called
peritoneum
what are some examples of endocrine glands
pituitary gland thyroid gland parathyroid gland adrenal gland pancreas ovaries testes
what is the mesothelium of the thoracic region called
pleura
what is the epithelial function of glands
produce and secrete substances
what is the epithelial function of teeth
produce enamel matrix
what are tight junctions and where are they found?
protein complex structures where cell membranes join together lateral wall near apical surface of epithelial cells
what is the shape and nucleus location of simple columnar cells
rectangular shape, nucleus positioned to one side
what color does silver stain show as?
reticular fibers - brown/black nerve fibers - brown /black
what is silver stain commonly used for?
reticular fibers and nerve fibers
what are some examples of exocrine glands
salivary glands eccrine and apocrine sweat glands sebaceous glands mammary glands ceruminous glands lacrimal glands
where can holocrine secretion be found
sebaceous glands of skin
what glands are derived from the ectoderm
sebaceous glands, eccrine glands, salivary glands mammary glands, pituitary gland, pineal gland
what happens in an apocrine secretion
secretion contents form a 'pimple-like' pouch at apical surface surrounded by membrane. Will pinch off upon release of the contents
what happens in holocrine secretion
secretion occurs upon cell death - both secretory product and cell debris are discharged together
what cell type makes up the endothelium and mesothelium
simple squamous epithelium
what are the three cell types found in epithelial tissue
squamous, cuboidal, columnar
why are most tissue samples stained with H&E as a comparison
stain will be present in all cells in the tissue
What is a Giemsa stain used for?
stains RBC's pink and leukocytes nuclei purple
what does trichrome stain?
stains collagen and cartilage blue stains epithelium and muscle fibers red/orange
what does verhoeff-van gieson elastic stain?
stains elastic fibers black
what is anatomy?
study of bodily structure, study of structures on a gross level
what is physiology?
study of normal organismal function healthy function
what is pathology? what does it use?
study of the causes and effects of disease uses laboratory examination of samples for diagnostic or forensic purposes
Where can stratified squamous epithelium be found?
surface of skin, lining of mouth, throat, esophagus, rectum, anus, and vagina
what is the apical surface and what characterizes it?
the free surface, top of the cell facing lumen characterized by specializations based on where the cell is located
what do cytokeratins do?
they are expressed within the cytoplasm to give cells their architecture
the mesothelium of which body cavities are derived from the mesoderm?
thoracic (pleura) abdominal (peritoneum) pericardium (heart sac) surrounds male internal organs
what are the three types of junctions
tight (occluding) junctions, gap (communicating) junctions, and anchoring junctions
what is immunocytochemistry used for?
to visualize proteins within cells using biomolecules capable of binding target of interest allows us to see certain features within tissue since H&E is non-specific binding
if you are trying to find collagen protein within your tissue sample what stain would you use?
trichrome
how many layers does complex/stratified epithelium have
two or more
where can transitional epithelium be found?
urinary bladder or other urothelial structures
how does immunohistochemistry work?
utilizes antibodies that specific bind to the molecule or protein of interest on the surface of the tissue antibody will mark where it is present with either fluorescence or some characteristic of expression
if you wanted to look at fibers of elastic arteries under a microscope, what stain would you use?
verhoeff-van gieson / weigerts
how do secretions from exocrine glands get released?
via ducts to epithelial surfaces