amniotic sac

Từ điển WordNet v3.1 - WordNet Dictionary

noun

thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)
• Syn:
amnion, amnios
• Derivationally related forms:
amniotic (for: amnion), amnionic (for: amnion), amnic (for: amnion)
• Topics:
mammal, mammalian
• Hypernyms:
sac
• Part Holonyms:
amniote, fetal membrane