Intestinal villus

Microanatomy File:Gray1059.png|Vertical section of a villus from the dog's small intestine. X 80. (Simple columnar epithelium labeled at right, third from top.) File:Gray1060.png|Transverse section of a villus, from the human intestine. X 350.a. Basement membrane, here somewhat shrunken away from the epithelium.b. Lacteal.c. Columnar epithelium.d. Its striated border.e. Goblet cells.f. Leucocytes in epithelium.f’. Leucocytes below epbithelium.g. Blood vessels.h. Muscle cells cut across. File:Cross-section histology of small intestinal villi of the terminal ileum.jpg|Cross-section histology of small intestinal villi of the human terminal ileum. File:MCT Chicken jejunum oblique.jpg|MicroCT-based volume projection of the jejunal mucosa of a chicken. Virtual volume block with vertically truncated villi in oblique view. Scalebar = 0.2 mm. File:MCT Chicken jejunum horizontal cut.jpg|MicroCT-based volume projection of the jejunal mucosa of a chicken. Virtual horizontal cut through villi. Scalebar = 0.2 mm. Enterocytes, along with goblet cells, represent the principal cell types of the epithelium of the villi in the small intestine. ==Function==

There, the villi and the microvilli increase intestinal absorptive surface area approximately 40-fold and 600-fold, respectively, providing exceptionally efficient absorption of nutrients in the lumen. There are also enzymes (enterocyte digestive enzyme) on the surface for digestion. Villus capillaries collect amino acids and simple sugars taken up by the villi into the blood stream. Villus lacteals (lymph capillaries) collect absorbed chylomicrons, which are lipoproteins composed of triglycerides, cholesterol and amphipathic proteins, and are taken to the rest of the body through the lymph fluid. Villi are specialized for absorption in the small intestine as they have a thin wall, one cell thick, which enables a shorter diffusion path. They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream. They have a rich blood supply to keep a concentration gradient. File:Intestinal villus simplified.svg|Structure of a villus (see reference quoted in text) ==Clinical significance==

Villous atrophy In diseases of the small intestine the villi can become flattened due to the effects of inflammation, and the villi can sometimes disappear. This deterioration is known as villous atrophy, and is often a feature of coeliac disease. ==Additional images==

File:Nudemousejejunum EM.jpg|Microvilli (shaggy hair) show electron dense plaques (open arrow) at their apices. ==References==