What term is used to describe the "dead" protein cells that make up the stratum corneum?

• A. Corneocytes
• B. Keratinocytes
• C. Melanocytes
• D. Fibroblasts

Answer: (A)

The term that describes the "dead" protein cells that make up the stratum corneum is corneocytes. The stratum corneum is the outermost layer of the epidermis and serves as a protective barrier for the underlying layers of the skin. Corneocytes are essentially flattened, dead cells that are filled with keratin, which is a fibrous protein that provides strength and resilience to the skin. These cells are continuously shed and replaced, a process known as desquamation.

Keratinocytes are the predominant cells found in the epidermis, responsible for forming the skin's barrier, but they are not specifically the dead cells of the stratum corneum; they become corneocytes as they move towards the surface and lose their nuclei and organelles. Melanocytes are specialized cells that produce the pigment melanin, which is crucial for skin color and UV protection, but they do not make up the stratum corneum. Fibroblasts are located in the dermis and are involved in producing collagen and elastin, contributing to the structural support of the skin, but are not relevant to the composition of the stratum corneum. Thus, corneocytes are the correct term for the dead protein cells