chorionic villus

biology

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June 24, 2026

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Chorionic villi are small, vascular projections that are part of the placenta. They significantly increase the surface area of the placenta, facilitating the exchange of nutrients and oxygen from the mother to the fetus. These villi contain the same genetic material as the fetus.12

Because of this genetic link, a procedure called chorionic villus sampling (CVS) can be performed. This involves taking a small sample of chorionic villi, typically between 8 and 12 weeks of pregnancy. The sample is then analyzed to detect potential chromosomal abnormalities or genetic disorders in the fetus. CVS can be performed earlier in pregnancy than amniocentesis, allowing for earlier diagnosis and decision-making. However, it carries a slightly higher risk of fetal loss compared to amniocentesis.3415

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pregnancy
The uterus and the development of the placenta
…of the third week, the chorionic villi that form the outer surface of the chorionic sac are covered by a thick layer of cytotrophoblast and have a connective tissue core within which embryonic blood vessels are beginning to develop. The vessels, which arise from the yolk sac, connect with the…
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…of the third week, the chorionic villi that form the outer surface of the chorionic sac are covered by a thick layer of cytotrophoblast and have a connective tissue core within which embryonic blood vessels are beginning to develop. The vessels, which arise from the yolk sac, connect with the…
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villus
…the placenta are known as chorionic villi. Chorionic villi make up a significant portion of the placenta and serve primarily to increase the surface area by which products from the maternal blood are made available to the fetus. The outer epithelial layer of the chorionic villi is made up of…
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…the placenta are known as chorionic villi. Chorionic villi make up a significant portion of the placenta and serve primarily to increase the surface area by which products from the maternal blood are made available to the fetus. The outer epithelial layer of the chorionic villi is made up of…
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