what is the skin that grows under the nail
Nail (anatomy) The nail bed is the skin beneath the nail plate.[8][unreliable source?] Like all skin, it is made of two types of tissues: the deeper dermis, the living tissue which includes capillaries and glands,[9][unreliable source?] and the epidermis, the layer just beneath the nail plate, which moves toward the finger tip with the plate. The epidermis is attached to the dermis by tiny longitudinal "grooves"[5] called matrix crests (cristae matricis unguis).[3][9] In old age, the nail plate becomes thinner, and these grooves become more visible.[5]
Human skin Epidermis is divided into several layers where cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate and become filled with keratin. They eventually reach the top layer called stratum corneum and are sloughed off, or desquamated. This process is called keratinization and takes place within weeks. The outermost layer of the epidermis consists of 25 to 30 layers of dead cells.