Keratinocyte

Keratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. They are named for the protein that they produce, keratin, which is a key structural material in hair, nails, and the outer layer of skin.

Function

Keratinocytes are responsible for the production of keratin. This protein provides strength and resilience to the skin, hair, and nails. Keratinocytes also play a role in the immune response, as they can produce inflammatory mediators in response to skin injury or infection.

Structure

Keratinocytes are stratified, meaning they are arranged in layers. The bottom layer, known as the basal layer, is where new keratinocytes are produced. As these cells mature, they move up through the layers of the epidermis, eventually reaching the surface and flaking off in a process known as desquamation.

Life cycle

The life cycle of a keratinocyte involves several stages. First, the cell is produced in the basal layer of the epidermis. It then begins to produce keratin and other proteins, and moves up through the layers of the skin. Once it reaches the surface, it becomes a fully mature keratinocyte, also known as a corneocyte. These cells eventually flake off the skin surface, completing the life cycle.

Clinical significance

Abnormalities in keratinocytes can lead to a variety of skin conditions. For example, psoriasis is caused by an overproduction of keratinocytes, leading to thick, scaly patches of skin. Other conditions, such as ichthyosis, are caused by defects in the keratin produced by these cells.

See also

• Epidermis (skin)
• Keratin
• Desquamation
• Psoriasis
• Ichthyosis

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  Micrograph of keratinocytes, basal cells, and melanocytes in the epidermis
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  Proliferative response induced by a tumor promoter in the epidermis of a wild-type mouse
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  Civatte body