https://doi.org/10.1351/goldbook.10516
- In human embryology, the cellular, outermost extra-embryonicmembrane, composed of trophoblast lined with mesoderm.
Note: The chorion develops villi, becomes vascularized by allantoic vessels, and forms the fetal part of the placenta. - In mammalian embryology, the cellular, outer extra embryonic membrane, not necessarily developing villi.
- In biology, the noncellular membrane covering eggs of various animals, e.g., fish and insects.