Human Embryology and Teratology
Teaching text 17: Skin and musculature 6: Skin appendages: nails
At the end of the embryonic period, the epidermis thickens and forms nail fields in which nails grow, similarly to hairs, from epithelial invaginations. In the depth of the nail folds there are mitotically active matrix cells. Derivatives of these matrix cells differentiate to form horny cells which grow over the nail bed to form the nail plate. The nails grow slowly and reach the tips of the fingers immediately before birth.