Allantois

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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.
     [1913 Webster]



From WordNet (r) 2.0 [wn]:

  allantois
       n : vascular fetal membrane that develops from the hindgut in
           embryonic higher vertebrates (reptiles, birds and
           mammals)