What is the transitional layer in the epidermis that marks the change from actively dividing keratinocytes to dead cells?

The transitional layer in the epidermis that signifies the shift from actively dividing keratinocytes to dead cells is the stratum granulosum. This layer plays a crucial role in the process of keratinization, where cells begin to lose their nuclei and organelles, accumulating keratohyalin granules which are essential for the formation of keratin.

Within the stratum granulosum, the keratinocytes begin to flatten out and become filled with keratin, a protein that provides strength and waterproofing to the skin. The presence of these granules marks a critical transitional phase in the life cycle of skin cells, indicating that the cells are moving away from a state of active division towards eventual death as they migrate upwards to the surface.

Above the stratum granulosum is the stratum lucidum, which is a thin, translucent layer that only appears in certain areas of the body, such as the palms of the hands and soles of the feet. It primarily consists of dead keratinocytes and does not actively contribute to the transitional process.

The stratum corneum is the outermost layer of the epidermis, composed entirely of dead keratinized cells that are continually shed and replaced. While it is the final stage of these