Either of two types of perspiration glands in the skin .
Eccrine sweat glands, controlled by the sympathetic nervous system, use evaporation to cool the skin by secreting water when body temperature rises. Apocrine sweat glands, usually associated with hair follicles, are concentrated in the underarms and genital region. Starting at puberty, hormones stimulate them to continuously secrete a fatty sweat. Certain specialized glands, such as mammary glands and wax-secreting glands of the ear canal, probably developed from this type of gland.