SYMPATHETIC INNERVATION OF THE SWEAT GLANDS AND PILORRECTOR MUSCLES OF MACAQUES AND HUMAN BEINGS

Abstract

A loose network of catecholamine-containing nerve terminals (adrenergic nerves) has been demonstrated around some of the coils of human and macaque ecerine sweat glands with the histofluorescence method [1–4]. After administration of the monamine oxidase inhibitor nialamide plus norepinephrine, fluorescent fibers appeared in nearly all the coils of the macaque glands. Systemic injection of reserpine or local injection of either 6-hydroxydopamine (6-OHDA) or 5-hydroxydopamine (5-OHDA) caused complete disappearance of the fluorescent fibers around all glandular coils. Under varying physiologic conditions, there is considerable fluctuation in the concentration of norepinephrine in the adrenergic terminals of sweat glands. Fluorescent fibers appeared sporadically around the apocrine glands of human axillae. With the aid of the electron microscope many unmyelinated varicose axon profiles were seen in the vicinity of both ecerine and apocrine glands of human beings and macaques. Most of these profiles contained many small agranular and a few large dense-cored vesicles (cholinergic terminals); other profiles had small and large dense-cored vesicles (adrenergic terminals). The sweat glands of human beings and macaques, then, are innervated with large numbers of cholinergic terminals and a few adrenergic terminals. After macaque ulnar nerves were constricted, fluorescent catecholamines were demonstrated in the proximal sides of the axons. Subsequent denervation of the ulnar nerves induced degeneration of the periglandular terminals and disappearance of the fluorescent fibers in the fifth digits. Dense plexuses of fluorescent fibers were found in the piloarrector muscles of macaques. When viewed with an electron microscope, a majority of the unmyelinated terminal axons appeared to be adrenergic: a few appeared to be cholinergic.