Lab: Epithelia Flashcards
microvilli
will stain in PAS due to the glycocalyx
have a core consisting of f-actin filaments
sub-microscopic (can’t be seen except fuzzies)
terminal web
thickened apical intracellular f-actin cytoskeleton supporting the microvilli cores
f-actin core of microvilli ends in terminal web
terminal bar
LM staining corresponding to the junctional complex
Lamina lucida
directly connected to the cell membrane consists of mainly glycoproteins, most important ones are laminin and fibronectin
basement membrane (basal lamina)
a special CT interface between an epthelial sheet and the subjacent CT layer
lamina densa
darkly staining
consists type IV collagen. It is a fibrillar type of collagen which forms a very dense meshwork with fine fibers compared to type I or III collagen. Into that meshwork is inserted the collagen of the normal CT (type 7 collagen).
Why is the basement membrane important in stopping cancer?
The basement membrane loses its ability to contain cells that have undergone dysplasia thus allowing for an EMT to occur as epithelial cells migrate into the CT layer
cilia
long, motile, and have a core of “9+2” microtubules
stereocilia
extremely long microvilli
most apparent in the epididymis
Collagens that are structurally important to forming the basement membrane are:
type IV collagen
Common glycoproteins that are structurally important to forming the basement membrane are:
laminin and fibronectin
Where would you find simple squamous epithelia?
outer surfaces of an organ- mesothelium
blood (and lymphatic) vessels- endothelium
Where would you find simple columnar epithelia?
GI epithelium where they have absorptive and secretory functions
Where would you find stratified squamous epithelia?
areas exposed to abrasive forces, nonkeratinized covering wet surfaces such as oral cavity or vagina, and keratinized covering dry surfaces such as skin
endothelia are derived from:
derived via a mesenchymal-epithelial transition event from mesoderm
What is the “golden rule” in histology?
every free or lumenal surface in the body is lined by an epithelium
What are several specific functions of the endothelium?
the lumenal surface (towards the blood) interacts with blood cells flowing rapidly by. There, cell adhesion molecules selectively grab leukocytes and initiate the process of transporting them across the epithelium. Also, substances found on the basal surface (i.e. the outer part, towards the connective tissue) will initiate clotting if they are exposed to platelets
unilocular adipocytes
white fat cells. The nucleus in the white fat cell is displaced towards the wall of the cell, and the “space” in the middle is actually another ex vivo artefact caused by the necessity to dissolve fat from the tissue section before hydrophilic (lipophobic) stains such as H&E will be effective.
mesentery
Connective tissues that suspends the intestines in the peritoneal cavity
goblet cell
mucus-secreting cell
