ectoderm

Amniotic ectoderm is a single cell layer that forms the membrane surrounding the developing embryo.

In an unexpected twist, no part of the sea star ectoderm expresses a "trunk" genetic patterning program, suggesting that sea stars are mostly headlike.

After gastrulation, the embryo can be thought of as an onion with three layers: the ectoderm, the mesoderm and the endoderm.

These disks eventually formed the three main cell layers of the body: the endoderm, mesoderm and ectoderm.

Beyond that, researchers typically assess pluripotency by confirming that the cells can differentiate into the three primordial germ-layer tissues: endoderm, mesoderm and ectoderm.