Sweat gland. Coloured scanning electron micrograph (SEM) of a blocked sweat gland on the surface of human skin. This pore brings 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. Bacteria can get into your skin and cause an infection if a sebaceous gland (oil gland) or sweat gland in your skin becomes blocked. This can causes inflammatory swelling (spot, blackhead, whitehead) at the site of infection and the possible death of nearby tissue. In the worst cases a cavity may be created, which can fill with pus to form an abscess. Magnification x500 when printed 10cm wide.