Search Result for "allantois": 
Wordnet 3.0

NOUN (1)

1. the vascular fetal membrane that lies below the chorion and develops from the hindgut in many embryonic higher vertebrates (reptiles, birds and mammals); 



The Collaborative International Dictionary of English v.0.48:

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]


WordNet (r) 3.0 (2006):

allantois
    n 1: the vascular fetal membrane that lies below the chorion and
         develops from the hindgut in many embryonic higher
         vertebrates (reptiles, birds and mammals)