You searched for: “chorioallantois
1. The highly vascular fetal membrane that consists of the fused chorion and allantois, found adjacent to the eggshell in reptiles and birds and constituting the placenta in most mammals.
2. A membrane surrounding an embryo.

In a bird's or reptile's egg, it lies next to the shell. In mammals, it forms a major part of the placenta.

This entry is located in the following unit: chorio-, chori- (page 1)