Hautzellen

Hautzellen is a term used for the cells that make up the skin, especially those in the epidermis. The most abundant are keratinocytes, which form the bulk of epidermal cells. The term also covers other skin cell types present in the epidermis, such as melanocytes, Langerhans cells, and Merkel cells.

Keratinocytes originate from stem cells in the basal layer of the epidermis. They proliferate and migrate outward through the stratum spinosum and stratum granulosum, finally differentiating into enucleated corneocytes in the stratum corneum. During this process they synthesize keratin and lipids that create the skin’s waterproof barrier and participate in innate immunity. The epidermal turnover time is typically about one month in healthy adults.

Melanocytes reside in the basal layer and produce melanin, the pigment responsible for skin color. Melanin is transferred to keratinocytes and helps shield their DNA from ultraviolet radiation. Langerhans cells are dendritic antigen-presenting cells within the epidermis that contribute to immune defense. Merkel cells are mechanoreceptors associated with gentle touch, linked to nearby nerve endings.

Development and function: Hautzellen interact with other epidermal and immune cells to maintain barrier integrity, regulate hydration, and participate in wound healing through re-epithelialization after injury. They respond to environmental factors such as UV exposure by activating DNA repair and signaling pathways.

Clinical relevance: Abnormal function or turnover of Hautzellen underlies various skin disorders, including psoriasis and eczema, and malignancies such as melanoma, which originates from melanocytes. Keratinocyte dysregulation can also contribute to barrier defects and inflammatory skin diseases.