 The ectoderm contributes to the formation of many parts of the body, including the skin, sweat glands, hair, teeth, and nails.During embryonic development, these and/or other parts of the baby's body, including the lens of the eye, parts of the inner ear, the fingers and toes, or nerves, among others, may fail to develop normally.When a child has at least two types of abnormal ectodermal features—for example, malformed teeth and extremely sparse hair—the child is identified as being affected by an ED "syndrome."