Chorionic villus sampling is a prenatal diagnostic test performed for prenatal genetic testing involving a biopsy of placental tissue between 10 to 13 weeks gestation. The tissue harvested is the ...

In its early life, the placenta is called a chorion because it is formed from the chorionic villi - finger-like growths which develop on the fertilised egg to help it implant in the wall of the uterus ...