Neurulation

Neurulation is the process the body uses to form the nervous system. It's like making a map of your body and the most important roads. During neurulation, the embryo (fetus) makes three layers of cells called germ layers. The outer layer is the ectoderm and it will turn into the skin and parts of the eyes, ears, and nose. The middle layer is the mesoderm and it will become the bones, muscles, heart, and other organs. The innermost layer is the endoderm and it will become the lungs, intestines, and other inner organs. The cells in these layers will then begin to fold, stretch, and squeeze so they can all fit in the tiny body of the embryo. Some of them will combine to form the spinal cord and later brains, along with the nerves that will connect these parts of the body together. Neurulation happens very quickly, starting as early as 6 days after conception for humans!