Comprehensive
Dictionary Suite
Help
Help
Help
 
Advanced Dictionary      
Lookup History
yolk sac

yolk sac

 
pronunciation:
yok saek
part of speech: noun
definition 1: a membranous sac that nourishes the embryos of primitive mammals, bony fishes, sharks, reptiles, and birds.
definition 2: a similar organ in the human embryo that functions as the circulatory system until internal circulation begins.