| any of the tissues, derived from the fertilized egg, that enclose or otherwise contribute to the support of the developing embryo, as the yolk sac, allantois, amnion, and chorion. |
| embryonic membrane n. Any of the membranous structures closely associated with or surrounding a developing vertebrate embryo, including the amnion, chorion, allantois, and yolk sac. |
embryonic membrane n.
See fetal membrane.