And that ectoderm gives rise to the integumentary system of the human body and that includes the outer portion of the skin, the ears, the nails and the hair. Now because of an invagination process. As we'll see in just a moment, a portion of that ectoder makes its way into that developing embryo. And this forms the nervous system of the human body. And that includes the brain and the spinal cord and it also includes all the nerve cells that are part of the peripheral nervous system. We also form the pituitary gland that is found beneath that hypothalamus in the brain.