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MICRO IMAGE REVIEW #2: LABS 4-6. boggusrl@email.uc.edu. LAB #4 - EPITHELIUM. Epithelia: lines tubes or covers surfaces Cells held together by: Cell junctions Interdigitation of cell membranes Glycocalyx. Intro to Epi. Number of cells layers: 1 = simple More than 1 = stratified
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MICRO IMAGE REVIEW #2: LABS 4-6 boggusrl@email.uc.edu
LAB #4 - EPITHELIUM • Epithelia: • lines tubes or • covers surfaces Cells held together by: • Cell junctions • Interdigitation of cell membranes • Glycocalyx
Intro to Epi • Number of cells layers: • 1 = simple • More than 1 = stratified Shape of cells: • Squamous = flat • Cuboidal = square w/round nucleus • Columnar = taller than they are wide, oval nucleus
Simple Epithelium • Has 3 surfaces: • apical/upper/free surface that faces outside or into a lumen • Lateral surface that connects it to other cells • Basal surface that lies against the basement membrane
Look how the tops are flat…. • Transitional would be rounded on top. Don’t confuse!
Simple Columnar • Oval nuclei
Tip: • They will almost always have to show you simple columnar in the intestine b/c it isnt found a lot of other places. • Keep an eye out for the goblet cells and microvilli that are also associated with it. • Also, they may ask you about “interdigitating cell membranes.”
Here are goblet cells and microvilli w/ simple columnar Microvilli Goblet cell
Interdigitating cell membranes • Will most likely have to show you with EM
Pseudostratified columnar epithelium – ciliated and with goblet cells • Nuclei not at the same level • All touch the basement membrane but not all reach the lumen
If they show you pseudostrat it may have stereocilia if it is in the epididymis. Be aware.
Stratified epi of many fun varieties • Name them according to the cells facing the lumen – outermost cells. • Does not matter what the ones touching the basement membrane look like
Stratified squamous epi • If top layer has nuclei – NON keratinized • On wet surfaces - mucosa • If top layer has no nuclei and looks flaky and like its pulling off – keratinized • On dry surfaces, usually skin of some sort
Stratified cuboidal • Usually in glands
Stratified columnar • In glands too, don’t confuse with stratified cuboidal. Make sure to see if nucleus is round and in center of cell. If so, cuboidal. If nuclei a little more oval and not exactly in center, go for columnar
Strat. columnar • So even though the bottom layer here is cuboidal that doesn’t matter
Transitional • Pretty much only in the bladder • Often binucleate • Tops of cells bulge into lumen
Cell contacts • Terminal bar (my favorite) vs. junctional complex • Terminal bar in LM • Junc. Complex in EM *They will try to trick you. Do not be fooled.*
What is this? JUNCTIONAL COMPLEX!!!!!!!!
The JC has 3 parts • Zonula occludens • Tight junction • Cells pressed close together, looks black in between the 2 cells in EM • Zonula adherens • Lighter between the 2 cells than the zon occludens • If you cant see anything and there is an arrow in between a zon. occludens on top and a desmosome beneath (both of which are easier to see) then it is a zonula adherens • Macula adherens • Desmosome • Looks spiny b/c of the filaments branching out *they will ask you these. Be able to tell them apart*
Desmosomes • aka macula adherens • Have intercellular bridges • Can be more than one down the length of a cell
Gap Junction • This is what I found on google for gap junction. I don’t think this will be on the test
Will the real gap junction please stand up • Not spiny on the sides like the desmosome
Interdigitation of lateral membranes • Its in the lab book, its fair game
Basement membrane • Between epithelial cells and underlying tissue • Made by both epithelial cells and connective tissue cells • Epi cells secrete basal lamina = collagen and other stuff • CT cells secrete reticular fibers and other stuff
Don’t be alarmed • They may stain it funny
BASAL LAMINA • Like the terminal bar, different names in different tissues
hemidesmosomes • Pretty much just desmosomes on the basal side of the cells Also note the lamina lucida and lamida densa – they can only label these on EM
STUFF ON TOPS OF CELLS Microvilli Stereocilia Cilia Flagella
microvilli • Smooth border on top – not rough like cilia • Cant really distinguish individual microvilli like you can with cilia • Filled with actin filaments • Often in intestine • For absorption • Look for the columnar cells that you find there
Pics of microvilli • P.S. microvilli does NOT = glycocalyx. Glycocalyx is a carb covering. Lets demonstrate:
Microvilli contd • When in cross section do not confuse with cilia – cilia have TUBES inside them in the special arrangement, while microvilli have roughly 50 actin filaments in a bundle cilia microvilli