What is primarily composed within the stratum corneum?

The stratum corneum is the outermost layer of the epidermis and plays a critical role in the integumentary system. It is primarily composed of dead cells that are filled with keratin, which is a fibrous protein that provides structural strength and resilience to the skin. The presence of keratin substances within these dead cells forms a tough, protective barrier that safeguards the underlying layers of skin from environmental hazards such as pathogens, chemicals, and physical abrasions.

As skin cells in the deeper layers of the epidermis mature and migrate upward, they undergo a process called keratinization, transforming into these dead, flattened cells that contribute to the stratum corneum. This layer is crucial for maintaining hydration and preventing water loss, further emphasizing its protective role.

In contrast, the other options describe components that do not accurately represent the primary composition of the stratum corneum, such as living cells or factors related to pigmentation, which are more characteristic of the deeper layers of the epidermis. This underscores the unique and specialized function of the stratum corneum in ensuring the overall health and protection of the skin.