The skin structure and functional genes. (IMAGE)
Caption
The skin comprises three main layers: the epidermis (which consists of four sublayers), the dermis; and the hypodermis. Skin stem cells in the basal layer of the epidermis generate keratocytes, which protect the skin against noxious external factors. Melanocytes produce melanin pigment and Langerhans cells play key roles in the skin's immune surveillance by detecting pathogens and presenting their antigens to T cells. Merkel cells are specialized for the sense of touch. Adipose cells in the hypodermis provide insulation, cushioning, and energy storage, while along with fibroblasts connecting the skin to the underlying muscles and bones. Around the hair follicle bulge, stem cells generate transient amplifying cells that play crucial roles in hair follicle cycling, hair shaft regeneration, and the repair and regeneration of the epidermis. Key genes for the functionality of skin stem cells and differentiated cells are shown on the left and right side, respectively.
Credit
Harvard Medical School
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