yolk sac

1. 1.

   membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional

   Synonymsvitelline sacumbilical vesiclevesicula umbilicus

   Broadersac
2. 2.

   membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo

   Broadersac

Questions about yolk sac

What does yolk sac mean?

yolk sac means "membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional". That is the primary sense; the word has 2 in total, listed in full on this page.

What is another word for yolk sac?

Close synonyms include vitelline sac, umbilical vesicle, vesicula umbilicus. Each sense on this page lists its own synonyms, because a word with several meanings rarely has one substitute that works for all of them.

Is yolk sac a common word?

yolk sac is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.