The chorion lies closest to the placenta. The chorionic sac encompasses the fetus and the amnion and is covered with chorionic villi until the 8th week. After the 8th week, these villi are ...

The outer membrane (chorion) and trophoblast layer of the placenta are derived from the trophoectoderm of the blastocyst cells. Other extra-embryonic tissues, including the amnion (inner membrane ...

“I had nothing to lose,” Williams says. A placenta's amnion, also known as amniotic membrane – a thin inner layer of tissue that once surrounded an embryo — was applied to his foo ...