1. the outermost membrane surrounding an embryo in reptiles, birds, and mammals
Usage: biology
2. the outer membrane of an insect egg
Usage: entomology

Examples

• The chorion helps protect the developing embryo from environmental hazards.
• In mammals, the chorion contributes to the formation of the placenta.
• The chorion of bird eggs is permeable to gases but not to water.
• Researchers studied the chorion structure in various insect species.
• The chorion provides essential nutrients to the growing embryo.
• Damage to the chorion can affect embryonic development.