What does the stratum corneum primarily consist of?

The stratum corneum is the outermost layer of the epidermis and primarily consists of dead keratinized cells. This layer serves as a critical protective barrier for the underlying layers of the skin. The cells in this layer have undergone a process called keratinization, where they become filled with keratin, a tough, fibrous protein that provides strength and waterproofing properties.

This layer's composition is essential for maintaining skin health, as it prevents water loss and protects against environmental damage, pathogens, and physical abrasions. The presence of dead cells is actually beneficial, as they help form an effective barrier while continually being replaced by the living cells emerging from the lower layers of the epidermis.

The other options do not accurately describe the stratum corneum; living cells pertain more to the layers below it, melanocytes are responsible for pigment production and are located deeper in the epidermis, and carcinogenic cells refer to abnormal cells that can lead to cancer, which is unrelated to the normal structure and function of the stratum corneum.