hair [AS, haer] , a filament of keratin consisting of a root and a shaft formed in a specialized follicle in the epidermis. There are three stages of hair development: (1) anagen, the active growing stage; (2) catagen, a short interlude between the growth and resting phases; and (3) telogen, the resting (club) stage before shedding. Scalp hair grows at an average rate of 1 mm every 3 days, with body and eyebrow hair growing at a much slower rate. Hair plucking does not stop hair growth. See also hirsutism, lanugo.
