Are the extraembryonic membranes the same in all vertebrates?

4 months ago

The presence of each extraembryonic membrane varies according to the vertebrate class. In fishes and amphibians only the yolk sac is present. In reptiles and birds besides the yolk sac there are also the amnion, the chorion and the allantois. In placental mammals besides all these membranes the placenta is present too.

Dipti KC
May 26, 2023
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