Which extraembryonic membrane in humans prevents desiccation of the...

Amnion is an extraembryonic membrane that surrounds embryo in reptiles, birds and mammals. It provides a kind of private aquarium to the embryo and protects it from mechanical shock and desiccation. Chorion (serosa) is the outermost extra embryonic membrane in reptiles, birds and mammals. It surrounds the whole embryonic system of embryo. Yolk sac contains yolk in reptiles and birds. In mammals, yolk sac is also known as umbilical vesicle. It is connected to enteron of embryo by a slender yolk stalk. Allantois functions as an embryonic urinary bladder or as a respiratory extension of hind gut in reptiles and birds. In mammals, it is modified to carry blood vessels to and from the placenta.