Definitions

1. noun

the innermost of the three primary germ layers in the very early embryo, giving rise to the lining of the digestive tract, respiratory tract, and other internal organs, and also to the epithelial linings of glands and other ducts, and to the connective tissue of the lining of the peritoneum and the pleura.

“The endoderm is the primary germ layer that gives rise to many of the internal organs in the human body.”