Mitosis takes place in the stratum:
Germinativum
The epidermis is composed of several layers: The stratum basale or stratum germinativum undergoes constant mitosis to replace the cells exfoliated from the skin's surface. The stratum basale, which is a row of columnar cells resting on the basal lamina that separates the epidermis from the dermis. Mitosis occurs exclusively at the basal cell layer and allows for the replacement of cells lost from the surface.