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Sweat pore. Coloured scanning electron micrograph (SEM) of a sweat gland pore (upper centre) opening onto the surface of human skin. The skin has been fractured to show the different layers. At the top, surrounding the pore, is the stratum corneum, a layer of dead skin cells produced from the epidermis beneath. At the base of the skin is the dermis, which contains sweat glands, hair follicles, blood vessels and nerves. As sweat evaporates from the surface of the skin, it removes heat and prevents the body from overheating. Sweat pores vary in shape and size over the body. (KEYSTONE/SCIENCE PHOTO LIBRARY/STEVE GSCHMEISSNER)