A membranous appendage of embryos of animals wild birds and reptiles in mammals providing for connecting the fetus with all the mother or father the urinary vesicle
- the vascular fetal membrane layer that lies below the chorion and develops through the hindgut in many embryonic greater vertebrates (reptiles, birds and animals)
- Alt. of Allantoid
The level of placenta closest toward inside.
(n.) Alt. of Allantoid
It is urged that the imperfect placenta of the bandicoots instead of being vestigial, may be an instance of parallelism, and that in marsupials generally the allantois failed to form a placental connexion.