Effects of Adrenergic Activators and Inhibitors on the Sweat Glands

Abstract

Sweat glands have been defined as all those cutaneous glands other than sebaceous glands that produce a secretion onto the surface of the skin. This loose definition encompasses a wide variety of structures with a broad range of functions. Some, such as the dermal glands of the hippopotamus or the nasal disc of the pig, have never been identified as sweat glands, whereas other glands are so specialized that it is difficult to decide how they might be classified. On a purely anatomical and embryological basis Bligh (1967) coined the terms epitrichial to refer to glands associated with hair follicles, and atrichial for those that open onto the epidermal surface independent of hair follicle units. Schiefferdecker (1917, 1922) classified glands associated with hair follicles as apocrine and those that have a duct which spirals through the epidermis and are independent of hair follicles or sebaceous glands as eccrine. This is the more conventional terminology although it is based on a suggested mode of secretion that is probably erroneous (Jenkinson, 1967). There does, however, appear to be a physiologic distinction between the two types of glands since eccrine glands are innervated largely by cholinergic nerves and apocrine glands by adrenergic nerves. Thus it is possible to examine sudomotor transmission alone without having to classify them on the basis of structure or function of the gland. In fact, there is considerable functional overlap. For example, in man and many primates, eccrine glands are concerned with thermoregulation, whereas in cattle and horses apocrine glands serve this function. Likewise, the sweat glands on the foot pad of the cat and dog aid frictional resistance and are eccrine, whereas those on the feet of the koala bear are apocrine.