Final answer:
Mitosis in the epidermis takes place in the stratum basale, which is the innermost layer of the epidermis containing basal cells that divide to form new keratinocytes.
Step-by-step explanation:
Mitosis or cell division in the epidermis occurs in the stratum basale. The stratum basale is the innermost layer of the epidermis and contains stem cells known as basal cells. These basal cells divide to produce new keratinocytes, which are the main type of cell found in the epidermis. As they divide, newly formed keratinocytes begin as cube-shaped cells with minimal keratin but, over time, as they are pushed upward by the continuous production of new cells, they accumulate more keratin and undergo a process of differentiation, resulting in the distinct layers of the epidermis.
The stratum basale is responsible for the ongoing regeneration of the epidermis and also houses melanocytes, which produce melanin, and Merkel cells. Above the stratum basale is the stratum spinosum, where keratinocytes become tougher and flatter, beginning their transformation into the protective layer of the skin. Cellular differentiation continues through the stratum granulosum and eventually leads to the formation of the stratum corneum, the outermost layer composed of flat, dead keratinocytes that form a tough, waterproof barrier.