Final answer:
Keratinocytes are produced in the stratum basale, the deepest layer of the epidermis, where basal cells divide to form these new skin cells.
Step-by-step explanation:
Keratinocytes are produced in the stratum basale, which is the innermost or deepest layer of the epidermis. In the stratum basale, basal cells divide to form new keratinocytes. As they mature, keratinocytes accumulate keratin and migrate through the different layers, eventually reaching the stratum corneum where they form a tough outer protective layer. The stratum spinosum, which comes just above the stratum basale, contains Langerhans cells along with keratinocytes that are beginning to accumulate keratin.
However, these cells are already formed in the stratum basale before they migrate to the stratum spinosum and other layers. The skin is composed of two major layers: the epidermis (superficial layer) and the dermis (deeper layer). The stratum basale is the innermost layer of the epidermis and it contains stem cells called basal cells, which divide to form all the keratinocytes of the epidermis