chorionic villi

Chorionic villi

Microscopic, finger-like projections that emerge from the outer sac which surrounds the developing baby. Chorionic villi are of fetal origin and eventually form the placenta.

Mentioned in: Chorionic Villus Sampling

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chorionic [kor″e-on´ik]

pertaining to the chorion.

chorionic villi numerous branching projections from the external surface of the chorion that provide for exchange between the maternal and fetal circulation. Oxygen and nutrients in the maternal blood diffuse through the walls of the villi and enter the blood of the embryo or fetus. Carbon dioxide and waste products diffuse from blood in the fetal capillaries through the walls of the villi into the maternal blood. See also chorionic villus sampling.

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villus [vil´us] (L.)

a small vascular process or protrusion, as from the free surface of a membrane.

arachnoid villi microscopic projections of the arachnoid into some of the venous sinuses.

chorionic villi see chorionic villi.

intestinal villi multitudinous threadlike projections covering the surface of the mucous membrane lining the small intestine, serving as the sites of absorption of fluids and nutrients.

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