Which skin layer is primarily made up of keratin?

The stratum corneum is the outermost layer of the epidermis and is primarily composed of keratin. Keratin is a tough, protective protein that forms the primary structural element of this layer, providing a barrier against environmental damage, pathogens, and water loss. This layer consists of dead keratinized cells that continually shed and are replaced, playing a critical role in maintaining skin integrity and health. The presence of keratin in the stratum corneum is vital for the skin's protective function and contributes to its resilience.

In contrast, the dermis, while important for providing structure and support to the skin, is primarily made up of connective tissue and does not have a significant keratin component. The epidermis consists of several layers, but only the stratum corneum is specifically noted for its keratin content. The stratum basale, the deepest layer of the epidermis, contains living cells that are actively dividing and do not contain the high concentrations of keratin found in the stratum corneum. Therefore, the focus on the high keratin content specifically identifies the stratum corneum as the correct answer.