ectoderm /ek″tədurm/ [Gk, ektos, outside, derma, skin] , the outermost of the three primary cell layers of an embryo. The ectoderm gives rise to the nervous system; the organs of special sense, such as the eyes and ears; the epidermis and epidermal tissue, such as fingernails, hair, and skin glands; and the mucous membranes of the mouth and anus. See also embryo, endoderm, mesoderm. −ectodermal, ectodermic, adj.
