What is the primary component of the stratum corneum?

The primary component of the stratum corneum is keratin. This layer is the outermost part of the epidermis and plays a crucial role in protecting the underlying tissues from environmental damage, pathogens, and water loss. Keratin is a fibrous protein that provides strength and resilience, making the skin barrier tough and durable.

In the stratum corneum, keratinocytes, which are specialized skin cells, become filled with keratin as they move towards the surface of the skin. As they accumulate keratin, they lose their nuclei and organelles, forming the tough, protective layer of dead cells that make up the stratum corneum. This adaptation is vital for maintaining skin integrity and function.

Other components listed, such as collagen, elastin, and melanin, play significant roles in skin structure and functionality, but they are not primarily associated with the stratum corneum. Collagen provides structural support in the dermis and contributes to the skin's elasticity and firmness, while elastin allows the skin to return to its original shape after stretching. Melanin is responsible for skin pigmentation and protection against UV radiation, but it is not a component of the stratum corneum itself.