Chorionic villi

Chorionic villi are microscopic, finger-like projections that emerge from the embryo's chorion to provide maximum contact area with the maternal blood. They are a critical part of the placenta, facilitating the exchange of nutrients, gases, and wastes between the mother and the fetus.

Structure

The chorionic villi are composed of a core of mesoderm cells, which includes blood vessels, 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, provides support.

Function

The primary function of the chorionic villi is to facilitate the exchange of nutrients, gases, and wastes between the mother and the fetus. The villi are bathed in maternal blood, and the thin walls of the villi allow for the easy diffusion of substances between the maternal and fetal bloodstreams.

In addition to this, the chorionic villi also produce several hormones, including human chorionic gonadotropin (hCG), which is crucial for maintaining pregnancy.

Clinical significance

Abnormalities in the development or function of the chorionic villi can lead to complications in pregnancy. For example, in placenta previa, the placenta implants too low in the uterus, potentially blocking the cervix and leading to bleeding.

Chorionic villus sampling (CVS) is a prenatal test where a small sample of chorionic villi is removed from the placenta for genetic testing. This can provide information about the baby's genetic health early in pregnancy.

See also

• Placenta
• Embryo
• Pregnancy
• Chorionic villus sampling