- allantois
[allantois 词源字典]
- "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", Mid 17th century: modern Latin, based on Greek allantoeidēs 'sausage-shaped'.[allantois etymology, allantois origin, 英语词源]