villus

(vĭl'əs)
n., pl., vil·li (vĭl'ī).

1. Biology. A minute projection arising from a mucous membrane, especially:
   1. One of the numerous vascular projections of the small intestine.
   2. One of the fingerlike projections of the chorion that contribute to the formation of the placenta in mammals.
2. Botany. A fine, hairlike epidermal outgrowth.

[Latin, shaggy hair.]

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Finger-like projections from the surface of some membranes (e.g. those of the small intestine ( that increase the surface area for the absorption of nutrients.

Pl. villi [L.] a small process or protrusion, as from the free surface of a membrane.

• arachnoid v. — microscopic projections of the arachnoid into some of the venous sinuses. Called also arachnoid granulations.
• chorionic v. — threadlike projections originally occurring uniformly over the external surface of the chorion.
• intestinal v. — multitudinous threadlike projections covering the surface of the mucous membrane lining the small intestine, serving as the sites of absorption of fluids and nutrients.

  Organization of an intestinal villus. By permission from Guyton R, Hall JE, Textbook of Medical Physiology, Saunders, 2000

• synovial v. — slender projections from the surface of the synovial membrane into the cavity of a joint; called also haversian glands.

For a list of words related to villus, see:

• Digestive and Excretory System - villus: small, fingerlike structure growing out of mucous membrane of small intestine that absorbs and carries off food material

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