Sweat gland. Coloured scanning electron micrograph (SEM) of sectioned human skin, showing a sweat gland (blue) under the surface. This gland is one of many releasing sweat onto the surface of the skin through sweat pores. This has the effect of cooling the body, as the sweat's evaporation carries away heat. The skin layers seen here are, from top to bottom: the stratum corneum (flaky, pale brown), a surface layer of flattened, dead skin cells that are continuously being shed and replaced by cells from the thin epidermal layer below (red). The lowest layer (grey-brown) is the dermis, a thick layer of fibrous connective tissue that supports and nourishes the epidermis. Magnification: x50 when printed 10cm wide.