The amnion is a membranous sac that surrounds and protects the embryo in reptiles, birds, and mammals. It creates an aquatic environment necessary for embryo development on land.
5 Must Know Facts For Your Next Test
The amnion is one of the four extraembryonic membranes in vertebrates.
It is filled with amniotic fluid, which cushions the developing embryo.
The presence of an amnion is a key feature distinguishing amniotes (reptiles, birds, and mammals) from amphibians and fish.
Amniotic fluid plays a critical role in preventing desiccation and providing mechanical protection.
The development of the amnion allowed vertebrates to reproduce away from water.