Morphological Connections of the Human Apocrine and Eccrine Sweat Gland - Occurrence of the So-called "Mixed Sweat Glands" - A Review

In human axillary, perianal and nasal Ala skins eccrine (e) and apocrine (a) sweat glands were light microscopically studied and five cases of the so-called "mixed sweat gland" (mixed sweat glands I, II, III, IV and V) were observed. In the mixed sweat glands the secretory cells of the aand e-sweat glands co-existed in one and the same gland in a variety of fashion either being restricted in a small portion of the secretory tubules or spreading in the wide range of the gland in contradiction to the concept of Schiefferdecker that both sweat glands represent perfectly disconnected, quite distinct glands. Our light microscopic studies have revealed that the superficial cells of the e-sweat gland exhibited also the picture of the apocrine secretion, though the activity of secretion was inferior to that of the a-sweat gland cells. The presence of the mixed sweat glands naturally suggest that between the both types of the sweat gland the transformation might take place. The mixed gland IV showed especially the sequence of the gradual transformation of the a-sweat gland into the e-sweat gland. The mixed sweat gland II and V suggested, in agreement with the mixed gland IV, also the transformation of the a-sweat gland into the e-sweat gland, since in the secretory epithelium of a-gland appeared the clear basal cells holding secretory canaliculi between themselves. The clear basal cells might derived from myoepithelial cells (Yasuda,1959). In the mixed sweat gland II the clear basal cells appeared close to the membrana propria as if to occupy the position of the myoepithelial cells. In the mixed sweat gland I, II, IV and V it was thought necessary that luminal a-gland cells turned into the superficial cells of the e-gland for complete transformation of the a-sweat gland into the e-sweat gland; the Yasuda's proposal (1959) that the possibility of transition of a-sweat gland cells into the dark superficial cells of the e-sweat gland was rather easy to understand.