amnion

Between these is a gelatinous substance, and within the amnion is a fluid, called the liquor amnii.

The whole being surrounded by two membranous coverings, the outer one called the chorion, and the inner one the amnion.

The amnion forms a small fold covering over the cephalic extremity of the embryo, which is deeply embedded in the yolk.

Both it and the stalk of the yolk-sack are enveloped by the amnion (am).

It adheres to the amnion and supplies it with blood-vessels (Bischoff).