Final answer:
The nail matrix, a deep layer of epidermal tissue located at the proximal end of a nail, contains stem cells that produce keratinocytes, which in turn produce the keratin that forms the nail body. The nail matrix also gives rise to the lunula when covered by epithelium, and the nail bed appears pink due to underlying blood vessels.
Step-by-step explanation:
The nail matrix is the key structure responsible for the growth of the nail and is a deep layer of epidermal tissue located at the proximal end of a nail. This matrix contains stem cells that divide and give rise to keratinocytes, which produce the protein keratin. This process extends the nail root and contributes to the formation of the nail plate, commonly known as the nail body, which is visible externally.
The nail body is composed of densely packed dead keratinocytes and protects our finger and toe tips from mechanical stress. The nail bed sits beneath the nail plate and is rich in blood vessels, making it appear pink. At the base of the nail bed resides the nail matrix which, when covered by a thick layer of epithelium, forms the lunula, a crescent-shaped white area.
The lateral nail fold helps anchor the nail body by overlapping it at the sides, while the eponychium, or nail cuticle, is a fold of epithelium that extends over the proximal end of the nail bed. The hyponychium lies under the free edge of the nail and consists of a thickened layer of stratum corneum.