Definitions

1. noun

The outer layer of the embryo, especially in birds, formed from the epiblast and hypoblast cells.

“During embryonic development, the formation of the chorion is a critical step in the formation of the placenta.”

2. noun

The outer membrane of the embryo, formed from the cells of the epiblast and hypoblast.

“The chorion plays a crucial role in the exchange of gases and nutrients between the mother and the developing embryo.”