What defines the stratum corneum?

The stratum corneum is defined by its composition of 20 to 50 rows of flattened, dead cells that are rich in keratin. This outermost layer of the epidermis plays a crucial role in providing a protective barrier for the underlying tissues. The cells in the stratum corneum are continuously shed and replaced, a process essential for maintaining healthy skin. The keratin present within these cells makes them resilient and waterproof, guarding against environmental factors, pathogens, and preventing water loss from the body.

In contrast, the other options describe aspects that do not accurately represent the stratum corneum. Layers of living cells that are actively dividing refer to the deeper layers of the epidermis, such as the stratum basale and stratum spinosum, where cell proliferation occurs. Partially flattened cells that provide elasticity might pertain to different layers of the epidermis or the dermis, which has its own structures contributing to skin elasticity. Lastly, describing only a few rows of highly keratinized cells does not capture the full extent of the stratum corneum, as it is characterized by a much greater number of cell layers, contributing to its thickness and protective function.