Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of the chorion is found beset with fine processes, the so-called chorion villi, which give it a rough and shaggy appearance. Shown is a magnified view of chorion villi.

Magnified View of Chorion Villi

Very soon after the entrance of the ovum into the uterus, in the human subject, the outer surface of…