Answer:
Chorion
Step-by-step explanation:
The chorion is made up of thick hypocellular collagen-like stroma that is filled with muscular chorionic vessels. It is found in mammals, birds, and reptiles.
The amniotic sac consists of two sacs/layers, the inner sac called the amnion, housing the amniotic fluid and fetus. The outer layer, the chorion which is part of the placenta.