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. 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.
3. 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.
