amnion

But a single placenta can make anywhere between 50 to 100 amnion grafts.

A method to correctly specify amnion formation is important to be able to recapitulate human embryo development as closely as possible using stem cell-based embryo models.

Its major adaptive advantage is the amnion — an enclosing membrane that prevents the embryo from drying out, and the principal feature to which the amniotic egg owes its name.

Until recently, pre-natal screening required invasive procedures such as amniocentesis, in which the fluid from the sac surrounding the foetus, the amnion, is sampled and the DNA examined for genetic abnormalities.

The embryo of a moth, a dragon-fly or a bug is invaginated into the yolk at the head end, the portion of the blastoderm necessarily pushed in with it forming the amnion.