n. 尿囊

[医] 尿囊

[ noun ]
the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals)
<noun.animal>

Allantois \Al*lan"to*is\, Allantoid \Al*lan"toid\, ] n.. (Anat.)
A membranous appendage of the embryos of mammals, birds, and
reptiles, -- in mammals serving to connect the fetus with the
parent; the urinary vesicle.