allantois
/æˈlæntəʊɪs/noun
(pl.allantoides /-ɪdiːz)
- the fetal membrane lying below the chorion in many vertebrates, formed as an outgrowth of the embryo's gut. In birds and reptiles it grows to surround the embryo; in eutherian mammals it forms part of the placenta尿囊。
派生词
allantoic
adjectiveallantoid
adjective词源
mid 17th cent.: modern Latin， based on Greek allantoeidēs 'sausage-shaped'.