Nails
the distal ends of the digits of humans and other primates have nails, whereas reptiles, birds, and most mammals have claws or hooves.
the nail is a thin plate, consisting of layers of dead stratum corneum cells that contain a very hard type of keratin.
the visible part of the nail is the nail body, and the part of the nail covered by skin isthe nail root (figure 5.7).
the eponychium, orcuticle, is stratum corneum that extends onto the nail body.
the nail root extends distslly from the nail matrix.
the nail also attaches to the underlying nail bed, which is located distal to the nail matrix and bed epithelial tissue with a stratum basale that gives rise to the cells that from the nail.
the nail matrix is thicker than the nail bed and produces most of the nail.
a small part of the nail matrix, the lunula, can be seen through the nail body as a whitish, crescent-shaped area at the base of the nail.
the production of cells within the nail matrix results in growth of the nail.
unlike hair, nails grow continuously and not have a resting stage.