Human skin. Coloured scanning electron micrograph (SEM) of healthy human skin. The flaky outer layer is made up of dead skin cells, which are being constantly shed and replaced. This process is known as desquamation. Skin consists of an outer epidermis of many cell layers supported by an underlying dermis. It accounts for around 15% of the body weight of humans. Its structure varies according to location, for example the skin on the hands and feet is much thicker than in other areas. The ability of skin to differentiate gives rise to hair, nails, sebaceous glands and sweat glands. Magnification unknown.