Yolk Sac (Noun)
Meaning 1
Membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo.
Classification
Nouns denoting animals.
Meaning 2
Membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional.
Classification
Nouns denoting animals.