Branched Eccrine Sweat Glands in Normal Human Skin

Abstract

THE human eccrine gland is described in textbooks as being made up of a single convoluted secretory tubule continuous with an excretory duct opening to the skin surface at the sweat pore¹. If this were universally true, the numbers of glands could always be equated with the numbers of pores, an inductive assumption made by many anthropologists when comparing the numbers of functional sweat glands in different races by means of pore counts, and also often assumed by physiologists concerned in sweat secretion². In contrast, most embryologists expect to find some variation from the norm as a result of developmental anomalies, and in an average person having some three million terminal eccrine sweat ducts³ it would indeed be strange if a proportion of the eccrine glands in every individual did not show some anomalous development. The most frequent variant might be expected to be fortuitous bifurcation at the rapidly dividing apex of the gland primordium, which during embryonic life grows downward from the epidermis into the dermis as a cord of cells⁴. Such an anomaly would inevitably result in the formation of twin glands having a common terminal excretory duct. If this occurred, it would render enumeration of the numbers of glands by pore counts rather less reliable, depending on the proportion of variant glands present.