What are keratinocytes and where are they located?

• A. Keratinocytes are the main cell type in the epidermis that produce keratin for protective barrier function.
• B. Keratinocytes are found only in the dermis.
• C. Keratinocytes produce melanin.
• D. Keratinocytes are nerve cells.

Answer: (A)

Keratinocytes are the main cell type in the epidermis, and they produce keratin, which gives skin its strength and helps form a protective, waterproof barrier. These cells originate in the deeper layers of the epidermis and migrate outward, becoming the flattened cells of the outermost layer. They are located in the epidermis, not the dermis, which is filled with connective tissue and other cell types like fibroblasts. Keratinocytes do not produce melanin (that’s the job of melanocytes), and they are not nerve cells. In short, the primary epidermal cells, keratinocytes, synthesize keratin to support the barrier function of the skin.