Stratum basale

Stratum basale (also known as the basal cell layer or basal layer) is the deepest layer of the five layers of the epidermis, the outer covering of skin in mammals.

The stratum basale is a continuous layer of cells, primarily composed of a single row of cuboidal or columnar keratinocytes that divide and push older cells up towards the surface of the skin. This layer also contains melanocytes, which are responsible for the production of melanin, the pigment that gives skin its color, and Merkel cells, which are involved in the sensation of touch.

Structure

The stratum basale is primarily made up of basal keratinocytes, the stem cells of the epidermis. These cells are constantly dividing and pushing already formed cells up and towards the surface of the skin. As they move up, they differentiate and eventually die to form the stratum corneum. This process is known as keratinization.

In addition to keratinocytes, the stratum basale also contains melanocytes, which produce melanin, and Merkel cells, which are associated with nerve endings and are responsible for the sense of touch. The stratum basale is also home to Langerhans cells, a type of immune cell that functions to recognize and process antigens present in the skin.

Function

The primary function of the stratum basale is to continually regenerate new skin cells, replacing the old cells that are shed from the surface. This is crucial for maintaining the integrity and health of the skin.

Melanocytes in the stratum basale produce melanin in response to UV radiation, protecting the skin from damage. They transfer the melanin to the keratinocytes, which use it to protect their DNA from UV damage.

Merkel cells in this layer are involved in the sensation of touch and the perception of shapes and textures.

Clinical significance

Damage or disease affecting the stratum basale can have serious effects on skin health. For example, basal cell carcinoma, the most common type of skin cancer, originates in the basal cells of the stratum basale.

Vitiligo is another condition that affects the stratum basale. It is characterized by the loss of melanocytes, leading to patches of skin without pigment.

See also

• Epidermis (skin)
• Keratinocyte
• Melanocyte
• Merkel cell
• Langerhans cell
• Basal cell carcinoma
• Vitiligo

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  Diagram showing the layers of the epidermis, including the stratum basale.
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  Microscopic view of normal epidermis and dermis with intradermal nevus at 10x magnification.
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  Illustration of skin layers, highlighting the stratum basale.