Which layer of the skin contains actively dividing cells?

The stratum basale, also known as the basal layer, is the deepest layer of the epidermis where actively dividing cells are located. This layer is primarily made up of keratinocytes, which undergo mitosis, producing new cells that will eventually migrate upwards to replenish the upper layers of the skin as they become damaged or shed.

The cells in the stratum basale are crucial for the continuous regeneration of the epidermis, ensuring that the skin remains healthy and intact. As these basal cells divide, they push older cells towards the surface, contributing to the overall process of skin renewal.

In contrast, the stratum corneum consists of dead, flat cells that have lost their nuclei and are primarily responsible for providing a protective layer. The stratum lucidum is found only in thick skin and is made up of a few layers of clear, flat, dead keratinocytes. The stratum granulosum contains cells that are in the process of dying and are accumulating keratin, but it does not contain actively dividing cells. Thus, when considering which layer is responsible for cellular division, the stratum basale is the correct choice.