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.

• 绒毛膜尿囊由融合的绒毛膜和尿囊组成的富含血管的胎膜组织，存在于爬行类动物和鸟类的蛋壳附近，并且构成大多数哺乳动物的胎盘。