Which layer of the epidermis contains fully keratinized cells?

The stratum corneum is the outermost layer of the epidermis and is composed of fully keratinized cells. This layer serves as a protective barrier for the underlying layers and is critical in preventing water loss and shielding the skin from environmental damage, including pathogens and physical abrasions.

As skin cells move upward through the layers of the epidermis, they undergo a process of keratinization, where they become filled with the protein keratin, losing their nuclei and becoming flattened. By the time they reach the stratum corneum, they are completely keratinized, offering the most effective form of protection for the skin. This makes the stratum corneum vital for maintaining skin health and stability.

The other layers, while important in their own right, do not consist of fully keratinized cells. The stratum granulosum contains cells that begin to lose their nuclei and dehydrate, the stratum lucidum is a thin, translucent layer found only in certain areas of thick skin, and the stratum spinosum consists of living cells that are still viable and have intercellular connections. Therefore, the primary role of the stratum corneum, with its fully keratinized cells, reinforces its essential function