Skin, coloured scanning electron micrograph (SEM) of a sweat gland pore and a hair on the surface of human skin. Sweat pores bring sweat from a sweat gland to the skin surface. The sweat evaporates, removing heat and playing a vital role in cooling the body and preventing it from overheating. Sweat pores vary in shape and size over the body. Hairs consist of a root which is implanted in the dermis of the skin and a shaft which represents the portion projecting from the epidermis. The shaft is divided into three concentric sheaths called the medulla, cortex and cuticle. The cuticle, the external sheath, is seen here; it is formed by a single layer of flat keratinised scales which overlap each other. Magnification: x2000 when printed 10 centimetres wide.