Amnion

The amnion is an extraembryonic membrane that surrounds the amnion. embryo developing amniote. It acts as a protective sac together with three other extra-embryonic membranes: the chorionthe yolk sac and the allantois . The membranes are then further enclosed by a shell (in birds, reptiles and some mammals) or on a uterus (in most mammals). The four membranes protect the developing embryo by providing gas exchange, supply of nutrients and excretion of waste .

Amniotes

The amniotes is a defining characteristic of the amniotes. amniotesa group of animals that includes reptiles, birds and mammals. Amniotes are thought to have diverged from non-amniote tetrapods some 300-350 million years ago. Amniotes are tetrapods that have evolved adaptations for living on land; vertebrate embryos require an aquatic environment to develop, and the amniote egg provides this environment. Amniotes have also evolved a number of other adaptations that allowed them to move away from water and exploit a larger terrestrial environment.

Structure of the amnion

The amnion is an extra-embryonic membrane that surrounds the amniote embryo. The membrane is not part of the embryo itself, but is derived from the tissues that emerged from the embryo. The amnion is made up of two germ layers: the mesoderm and the ectoderm. The ectoderm forms the inner part of the amnion and a thin layer of mesoderm connects the amnion to the chorion.

Amnion function

The amnion, together with the chorion, yolk sac and allantois, form a series of protective barriers that provide a life support system for the developing embryo. The four membranes function to exchange oxygen and dioxide carbon dioxide between the embryo and the placentato provide nutrients to the embryo and to remove nitrogenous waste from the embryo.

The amnion forms a sac filled with amniotic fluid. Amniotic fluid acts as a buffer to protect the embryo from physical damage due to mechanical shock. In addition, amniotic fluid also helps prevent dehydration and desiccation when bathing the embryo. Amniotic fluid is released at birth when the amnion ruptures. In humans, this is the phenomenon known as the rupture of the mother’s “waters”.

This figure represents a hen’s egg. It shows the four extraembryonic membranes surrounding the embryo: the amnion, the chorion, the allantois and the yolk sac.