ECTODERM: the outer (ekto) layer of the embryo.
ENTODERM: the inner (ento) layer of the embryo.
EPIDERM: the outer layer of the skin.
EPIGENESIS: the theory of gradual development of organs in the embryo.
EPIPHYSIS: the third or central eye in the early vertebrates.
EPISOMA: see SOMA.
EPITHELIA: tissues covering the surface of parts of the body (such as the mouth, etc.)
GONADS: the sexual glands.
GONOCHORISM: separation of the male and female sexes.
GONOTOMES: sections of the sexual glands.