Adipose Histology Flashcards
White adipose tissue (WAT) is also called… why?
unilocular adipose tissue - each cell has a single large droplet of fat which displaces other organelles to the cell periphery
brown adipose tissue (BAT) has what in contrast to WAT? called what bc of this?
many small fat droplets thus called multilocular fat
What term describes WAT?
signet rings - because large lipid droplet displaces the nucleus
the clear areas on fat slides are truly empty bc the triglycerides in the fat droplet are soluble in the organic solvents used in processing and are therefore removed
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WAT slides have numerous small blood vessels. WAT is highly vascularized. Sympathetic nerve endings are also present
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thymus has lots of adipose tissue when aged.
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WAT droplets squeeze the cytoplasm and nucleus to the periphery - cellular organells are present although not abundant. Collagen fibers adn fibroblasts are also surrounding the cells.
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Unilocular adipocytes appear as spheres on EM. WAT unilocular adipose has single fat droplet that is usually liquid at room temp. REtiular fibers (look like small threads) enmesh the adipocytes.
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In contrast to WAT, nuclei in BAT cells are..
roudn or oval and are centrally located!!
Many capillaries and vessels are still evident though.
The nuclei you see on the periphery for H&E of BAT is usually from fibroblasts of CT or endothelial cells of the blood vessels.
dont confuse mucus acinus and BAT - how to tell diff?
If mucus acinus – lots of peripheral nuclei
Also fat droplets of BAT have cytoplasm in between
axilla has BAT in it
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Mammary glad has both BAT and WAT.
BAT has numerous what in the cytoplasm?
mitochondria!
Developing what fat cells are what?
multilocular!!!
Both types begin as multiocular. BAT remains separate while WAT coelesce to form one large droplet.
When looking at slides, what terms are best to use?
multiocular and unilocular adipose! If you say white or brown, you are presuming what they are
may also say “either brown fat or developing white fat” if the tissue is multiocular
Can distinguish WAT/BAT using histochemistry. Stain with what?
Stain for uncoupling protein (UCP-1) - shows up brown in preparation.
UCP-1 is found where?
Found in the mitochonria of BAT cells but not in WAT cells. This protein dissipates the proton gradient before it can be used to provide the nergy for oxidative phosphorylation - resulting in heat instead of ATP
WAT and BAT are highly vascularized.. which is more vascularlized?
BAT!
What does the vasculature do in WAT?
Conveys FA to WAT for storage as TAGs and during mobilization, distributes the hydrolyzed FA and glycerol to other tissues
What does the vasculature do in BAT?
distributes the heat generated during arousal from hibernation in animals OR from cold or diet induced htermogenesis in man
Mucus glands center are what compared to BAT?
Clearer!!! - BAT also has a nucleus
Why is a tumor with BAT called a hiberoma?
Because BAT was first charactrized as being important in generating heat during arousal of animals from hibernation
Use sections with antibodies to UCP-1 found in mito of BAT but not WAT to tell the difference between tissues that are BAT or developing WAT.
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