What is the primary function of keratinocytes in the epidermis?

The primary function of keratinocytes in the epidermis is to provide a barrier and produce keratin. Keratinocytes are the most abundant cells in the outer layer of the skin, the epidermis, and they play a critical role in the skin's protective functions. As they undergo a process called keratinization, keratinocytes produce keratin, a tough, fibrous protein that helps form a resilient barrier against physical damage, pathogens, and dehydration.

The production of keratin is essential for maintaining the integrity of the skin, as it contributes to the formation of the stratum corneum, the outermost layer of the epidermis. This layer is comprised of dead keratinocytes filled with keratin, providing a waterproof barrier that is crucial for preventing water loss from the body and protecting underlying tissues from external insults.

Other functions such as the production of collagen by fibroblasts occur in the dermis, and while melanocytes aid in pigmentation and sensory cells detect touch sensations, these activities are not the direct functions of keratinocytes. Thus, the primary role of keratinocytes is accurately described by their ability to provide a protective barrier and produce keratin.