n. Zool. & Embryology
the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis, nerve tissue, and nephridia. Compare with endoderm and mesoderm.
/ ˌektōˈdərməl/ adj.
In a triploblastic
embryo, the outer layer of cells which eventually give rise to the epidermis
, the most anterior and posterior portions of the digestive tract, and the majority of the nervous system
ectoderm (ek-toh-derm) n.
the outer of the three germ layers
of the early embryo. It gives rise to the nervous system
and sense organs, the teeth and lining of the mouth, and the epidermis and its associated structures (hair, nails, etc.).
The external layer of cells of the gastrula
, which will develop into the epidermis and the nervous system
in the adult. See also germ layers