Ectoderm

The Ectoderm is the exterior of the first 3 primary germs layers of an embryo, which is the earliest stage of development for an organism. A germ layer is one of the first cell layers that form when an embryo begins to grow. The ectoderm forms on the exterior of the mesoderm (the middle germ layer) and the endoderm (which is the most interior germ layer). The ectoderm eventually goes to form our skin, nerves, spine, and brain.