ectoderm

Because both the brain and skin develop from the same embryonic layer called the ectoderm, the scientists set out to explore how these two systems might be connected.

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.