In which layer of the skin are keratin-containing cells primarily found?

Keratin-containing cells are primarily found in the stratum granulosum, which is a crucial layer of the epidermis. This layer plays a significant role in the formation of the skin's protective barrier.

The stratum granulosum is characterized by the presence of keratinocytes that begin to lose their nuclei and organelles while accumulating keratin filaments and keratohyalin granules. This process aids in the formation of the tough, protective layer of skin as these cells move up to the outermost layer. The keratin produced in this layer contributes to the skin's strength and waterproofing properties, essential for preventing water loss and protecting underlying tissues from environmental damage.

In contrast, while the stratum corneum also contains keratin, it is primarily made up of dead keratinized cells that have lost their nuclei and are not actively producing keratin anymore. The stratum basale consists of living cells that are actively dividing and responsible for generating new skin cells, but it does not contain the concentrated keratin found in the granulosum layer. Lastly, the stratum spinosum contains cells that are primarily involved in providing strength and flexibility to the skin, but these cells are not primarily focused on keratin production.