Eccrine secretion

Beyond physical barrier protection, several natural processes lead to skin surface conditions unfavorable to microbial growth. Both sebaceous and eccrine secretions are acidic, lowering the surface pH of the skin below that welcomed by most pathogens. This acid mantle (pH 5) [16] is moderately bacteriostatic. Sebum also contains a number of short-chain fungistatic and bacteriostatic fatty acids, including propanoic, butanoic, hexanoic, and heptanoic acids [17]. That the skin s surface is dry also offers a level of protection. It comes as no surprise that fungal infections and other skin infections are more prevalent in the skin s folds... 

Before we discuss how to test removal and destruction of the microbial skin flora, we must determine where the bacteria reside and how bacterial populations are maintained on the skin [6,7]. Gibbs and Stuttard [8] have described the skin as uneven in topology and thickness (Table 1), ridged, with openings of pores and ducts (Fig. 1). The skin may act as a physical barrier, though not as a chemical barrier. Both apocrine and eccrine secretions are vital to the microbial population, as well as repopulation after the removal of superficial flora. 

Eccrine glands can be found on the entire body surface of humans, except for the lips, external ear canal, clitoris, and labia minora. These glands play an important role in thermoregulation, which is necessary for fluid and electrolyte homeostasis. They secrete a milky or oily odorless liquid which produces the characteristic body smell after metabolism through surface bacteria of the skin. 

Eccrine (merocrine) sweat glands are simple tubular glands that open directly onto the skin surface (Figure 35.1). In humans, they are found over the entire body surface except for the lips, external ear canal, clitoris, and labia minora. Myoepithelial cells located in the secretory portion of these glands are specialized smooth muscle cells, which, upon contraction, aid in moving the secretions toward the duct. The eccrine sweat gland duct is comprised of two layers of cuboidal epithelium... 

The excretory portion in the skin involves secretion from the sebaceous glands and the apocrine and eccrine sweat glands. 

Secretion is effected in the deep parts called glomeruli. The secretory cells are cuboidal and are surrounded by a layer of myoepithelial cells which have contractile properties. The majority of the sweat glands are of the eccrine type. The sweat they produce is slightly acidic and is mostly composed of water. The evaporation of sweat from the skin allows a decrease in body heat. 

Hurley, H. J. Witkowski, J. Dye clearanee and eccrine sweat secretion in human skin. J. Invest. Dermatol. 1961, 36, 259-272. 

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