keratynocyte

Keratinocyte is a type of cell found in the epidermis, the outermost layer of the skin. These cells are the most abundant cell type in the epidermis, making up about 90% of the total epidermal cells. Keratinocytes are responsible for producing keratin, a tough fibrous protein that forms the main structural component of the epidermis, hair, and nails.

The life cycle of a keratinocyte begins in the basal layer of the epidermis, where they are produced through cell division. As new keratinocytes are formed, they move upwards through the different layers of the epidermis. During this migration, they undergo a process called differentiation, where they change in shape and composition. They accumulate keratin and flatten out.

As keratinocytes mature, they reach the stratum corneum, the outermost layer of the epidermis. Here, they are dead, flattened cells that are constantly being shed from the skin's surface. This shedding process, known as desquamation, is a continuous and essential part of skin renewal, helping to remove dead cells and protect the underlying tissues. Keratinocytes also play a role in the skin's barrier function, preventing the entry of pathogens and water loss. In addition to keratin production, some keratinocytes also contain pigment granules (melanin), contributing to skin color.