The amnion is a thin, protective membrane that surrounds the developing embryo in mammals, including humans. It forms a part of the amniotic sac, which contains amniotic fluid. This fluid cushions the embryo, providing a stable environment and allowing for movement, which is essential for proper development. During pregnancy, the amnion plays a crucial role in protecting the embryo from physical shocks and infections. It also helps maintain a consistent temperature and provides a medium for the exchange of nutrients and waste products. The amnion is one of the key structures that support the growth of the fetus until birth.