The stratum corneum is primarily composed of what type of cells?

The stratum corneum is the outermost layer of the epidermis, consisting primarily of keratinized cells known as keratinocytes. These cells are filled with keratin, a type of protein that provides structural integrity and waterproofing to the skin. This layer plays a crucial role in protecting underlying tissues from environmental damage, pathogens, and dehydration.

Keratinocytes originate from the deeper layers of the epidermis and undergo a process called keratinization as they move upward to the stratum corneum. This transformation involves the accumulation of keratin and the loss of their nuclei, resulting in the formation of tough, protective layers of dead cells that continually shed and are replaced.

While melanocytes are important for pigment production, epithelial cells represent a broader classification of cells forming the skin, and adipocytes are fat cells found in the subcutaneous layer, none of these cell types make up the stratum corneum in the same way that keratinocytes do. Thus, the primary composition of the stratum corneum is specifically keratin cells, which is why this choice is the correct answer.