Which skin layer contains the most active living cells?

The stratum basale, also known as the basal layer, is the lowest layer of the epidermis and is where the most active living cells are found. This layer is primarily composed of keratinocyte stem cells that undergo continuous mitosis to replenish the skin cells above them. As these cells divide, they push older cells upwards through the layers of the epidermis, leading to the formation of the outermost layer, the stratum corneum.

The high level of cellular activity in the stratum basale is critical for skin regeneration and repair, as it provides a constant supply of new cells to replace those that are shed from the surface. This layer also contains melanocytes, which produce melanin to protect the skin from ultraviolet (UV) radiation, and Merkel cells, which are involved in sensory perception.

In contrast, the other layers mentioned, such as the stratum corneum, stratum spinosum, and stratum granulosum, either contain cells that are more differentiated and less metabolically active or are primarily comprised of dead cells (in the case of the stratum corneum). Thus, the stratum basale stands out as the layer with the highest degree of cellular activity, making it essential for maintaining the