The epidermis consists of a lower layer where cells multiply and rise to the surface while manufacturing keratin. Which substance is produced in this process?

• A. Melanin
• B. Keratin
• C. Collagen
• D. Elastin

Answer: (B)

The process described is keratinization in the epidermis. In the lower, or basal, layer, cells divide to replenish the skin. As these cells rise toward the surface, they synthesize keratin, a tough, fibrous protein, and accumulate it. This keratin fills the cells as they move upward, eventually forming the dead, keratin-rich cells of the outermost layer that create a protective, waterproof barrier. That’s why keratin is the substance produced in this process.

Melanin is produced by melanocytes in the epidermis and affects coloration, but it isn’t produced during this keratin-producing maturation. Collagen and elastin come from fibroblasts in the dermis, not the epidermis, so they aren’t part of this keratinization process.