n. the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
常见例句
1
a relating to or characterized by an allantois
2
Of or pertaining to the allantois.
3
The division of Vertebrata in which the embryo develops an allantois
4
n the very vascular fetal membrane composed of the fused chorion and adjacent wall of the allantois
