What cells make up the epidermis?

The epidermis, the outermost layer of the skin, is composed of several types of cells, each with distinct functions:

1. Keratinocytes: Keratinocytes are the most abundant cells in the epidermis, accounting for approximately 90% of its cellular composition. They produce keratin, a fibrous protein that provides strength and防水to the skin. Keratinocytes are organized in multiple layers, with the innermost layer being the stratum basale and the outermost layer being the stratum corneum.

2. Melanocytes: Melanocytes are specialized cells that produce melanin, the pigment responsible for skin color and protection from ultraviolet (UV) radiation. Melanocytes are located in the stratum basale and are responsible for distributing melanin to the surrounding keratinocytes.

3. Langerhans cells: Langerhans cells are dendritic cells that belong to the immune system. They are located in the epidermis and function as antigen-presenting cells, playing a crucial role in immune surveillance and the initiation of immune responses.

4. Merkel cells: Merkel cells are specialized mechanoreceptor cells that are located in the stratum basale. They are associated with nerve endings and are responsible for detecting touch sensations, pressure, and vibrations.

5. Basal stem cells: Basal stem cells are located in the stratum basale and are responsible for the constant renewal and regeneration of the epidermis. They divide and differentiate into keratinocytes and other epidermal cells, maintaining the integrity and health of the skin.

These different cell types work together to provide protection, barrier function, immune defense, sensory perception, and the production of essential proteins for maintaining skin integrity.