Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun yolk_sac

2 senses of yolk sac

Sense 1
yolk sac, vitelline sac, umbilical vesicle, vesicula umbilicus -- (membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional)
       => sac -- (a structure resembling a bag in an animal)

Sense 2
yolk sac -- (membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo)
       => sac -- (a structure resembling a bag in an animal)