Intestinal Epithelial Cells

Question 1

Undifferentiated crypt cells/stem cells

Answer 1

located in basal portion of gland
divide –> other types of epith cells of gland and surface
intest epith is replaced every few days
if division is stopped, entire epith may be sloughed

Question 2

Goblet cells

Answer 2

secrete mucin (protective)
increase in #s caudally in intestine
type of mucin varies w/location

Question 3

enteroendocrine cells

Answer 3

several types
scattered singly thruout surface and glandular epith
imp. in hormonal regulation of GI functions

Question 4

paneth cells

Answer 4

only in base of gland (horse, ruminants, man)
have apical membrane bound granules w/lysozyme and peptidase
control microflora of crypts

Question 5

globular leukocytes

Answer 5

large eosinophilic globules/granules
small, heterochromatic nucleus
intraepithelial as well as in lamina propria

Question 6

M (microfold) cells

Answer 6

epith cells over lymphatic areas/nodules
apical surfaces w/blunt microvilli/ridges
derived from same stem cells as other epith cells
take up ags and pass to lymphocytes in invaginations of cell membrane

Question 7

intraepith lymphocytes

Answer 7

common thruout intestine

Question 8

intestinal absorptive cells/enterocytes

Answer 8

numerous on surface of villi in SI, luminal surface in LI and in glands of both
columnar, apical microvilli, striated border
apical tight junctions join adjacent cells - seal gut lumen
basal nucleus and RER, apical SER and golgi, many mitoch
glycocalyx covers mvilli = anchor for digestive & pancreatic

secretions:
enzymes into glycocalyx for final steps to digestion of proteins and carbs
active mvmnt of ions @ basal membrane
chylomicrons rel’d at lateral membrane by exocytosis

functions:
transport epithelium (uptake of small molecules)
resynthesis of TGs from FAs & formation of chylomicrons
endocytosis in neonate - IgG into absorptive cells 
Passes protease resistant IgA into lumen to fight invaders