The effects of thermal stimulation on the ultrastructure of the human atrichial sweat gland. I. The fundus

SUMMARY Ultrastructural examination of sweat glands from the human loin before and during heat‐induced activity indicated that the sweat is formed from the contents of disrupted cells as well as from the products of secretion. The principal secretory processes appear to be fluid transport and exocytosis of vesicles. However, configurations suggesting microapocrine secretion were also observed. It is concluded that the mechanisms involved in sweat production in man are fundamentally similar to those in animals and the terms ‘apocrine’ and ‘eccrine’ should be discarded. The myocpithelial cells which were contracted at the onset of sweating appeared to be under less tension after 3 h of continuous activity.