Final answer:
The active tissue responsible for generating cells that form the nail plate is known as the nail matrix, which is located at the proximal end of the nail and contains stem cells that divide to facilitate nail growth.
Step-by-step explanation:
The active tissue that generates cells which harden as they move outward to form the nail plate is called the nail matrix. The nail matrix is a deep layer of living epidermal tissue at the proximal end of the nail, responsible for nail growth. Stem cells in the nail matrix keep dividing to produce new nail cells, forming first the nail root and then the nail plate as the nail grows longer and emerges from the epidermis.
The nail plate is the main keratinous plate that forms the nail, providing protection to the tips of the fingers and toes which experience maximum mechanical stress. The nail bed, located beneath the nail plate, is rich in blood vessels giving it a pink appearance except at the lunula, a crescent-shaped region at the base of the nail. Contrary to the matrix, the nail cuticle or eponychium is a fold of epithelium that extends over the nail bed, and does not take part in the generation of the nail cells.