Medicogramover 3 years ago

This's a 10 weeks old embryo (Scanning electron micrograph). The sac in which the embryo is enclosed is known as Amnion or amniotic sac and the floral looking structure at the base of the amnion is known as Chorion frondosum. The chorion frondosum (literally "bushy chorion") arises from the polar pole of the human embryo trophoblast. It consists of a layer of trophblasts and extraembryonic mesoderm surrounded by numerous villi. This portion of the placenta is located at the site of implantation.