There are two types of secretory skin glands (sweat glands) found only in mammals, known as eccrine sweat glands and apocrine sweat glands. Both of these types of glands are located within the dermis, or lower layer of skin.
The eccrine sweat gland regulates body temperature and is regulated by the sympathetic nervous system. To maintain homeostasis, the eccrine glands release water, which is more commonly known as sweat, onto the skin’s surface as a means of counteracting an increase in internal temperatures; after the release of sweat, heat is removed from the body via evaporation.
Apocrine sweat glands are typically associated with hair follicles in the skin; these glands secrete fatty acids (sweat) into a gland tubule, which contacts and expels the fatty acids into the skin during emotional stress to the body. Apocrine glands are primarily located beneath the arm (armpit) and around the gentiles, which are usually inactive before puberty.