Epiblast

In amniote animal embryology, the epiblast is a tissue type derived either from the blastodisc in reptiles (incl. birds) or the inner cell mass in mammals. It lies above the hypoblast.

Mammals
In mammalian embryogenesis, the columnar cells of the epiblast are adjacent to the trophoblast, while the cuboidal cells of the hypoblast are closer to the blastocoele. The epiblast, whilst referred to as the primary ectoderm, differentiates to form all three layers of the trilaminar germ disc in a process called gastrulation.

Epiblast diversity
Human epiblast is disc-shaped as opposed to the mouse epiblast which is cup-shaped.