Chorionic villus

Chorionic Villus

The chorionic villus is a structure that forms part of the placenta in a pregnancy. It is a microscopic finger-like projection that emerges from the chorion, a membrane that contributes to the formation of the placenta. The chorionic villi are critical in the exchange of nutrients and waste products between the mother and the fetus.

Structure

The chorionic villus is composed of a core of mesoderm surrounded by two layers of trophoblast cells. The outer layer, known as the syncytiotrophoblast, is in direct contact with maternal blood, while the inner layer, the cytotrophoblast, is in contact with fetal blood. The mesodermal core contains fetal capillaries which are connected to the fetal circulation.

Function

The primary function of the chorionic villi is to facilitate the exchange of nutrients, oxygen, and waste products between the mother and the fetus. This is achieved through the close proximity of the maternal and fetal blood supplies, separated only by the thin trophoblast layer. The chorionic villi also play a role in the production of hormones such as human chorionic gonadotropin (hCG) and progesterone, which are essential for maintaining pregnancy.

Clinical Significance

The chorionic villi are the target of certain prenatal diagnostic tests, such as chorionic villus sampling (CVS). This procedure involves the removal of a small sample of chorionic villus tissue from the placenta for genetic testing. It can be used to detect a variety of genetic disorders, including Down syndrome, cystic fibrosis, and sickle cell anemia.

See Also

• Placenta
• Pregnancy
• Chorionic villus sampling

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