Structure of the tight junctions of the human eccrine sweat gland

Abstract

The human eccrine sweat gland contains two anatomically and functionally discrete segments: the secretory coil, which produces an isotonic or slightly hypertonic precursor fluid, and the coiled duct, which reabsorbs Na+ and Cl- to yield a hypotonic sweat. We examined the freeze-fracture morphology of tight junctions from isolated secretory coil and coiled duct segments to assess indirectly the contribution of paracellular ion transport in secretion and resorption in the sweat gland. In the secretory coil, tight junctions of the intercellular canaliculus and main lumen consisted of approximately 9 and 6, closely spaced, parallel or anastomosing elements, respectively. Tight junctions of the coiled duct were similar in appearance to those at the main lumen of the secretory coil. In both the secretory coil and coiled duct, and average of 2 to 3, widely spaced junctional elements were usually observed basolateral to the closely spaced junctional elements in the region corresponding to the location of the zonula adherens in Epon sections. The complexity of the tight junctions of the secretory coil exceeded what we expected for an epithelium secreting an isosmotic fluid. The elaborate tight junctions of the coiled duct support other evidence for an intermediate to high transepithelial resistance.

Chloride permeability regulation via a cyclic AMP pathway in cultured human sweat duct cells.

“…similar to the resistance predicted from a structural study of the tight junctions of the intact human sweat ducts (Briggman, Bank, Bigelow, Graves & Spicer, 1981). Such tight membrane prepara-tions notably allow the use of Ussing chamber techniques, including traditional isotope flux measurements and estimation of agents affecting the PD and transepithelial resistance, which in this tissue is representative of the Cl-permeability.…”

Freeze‐fracture and lead ion tracer evidence for a paracellular fluid secretory pathway in rat parotid glands

“…However, it has become clear that other factors besides number of sealing strands-for example, sealing strand continuity and geometry-are also important in determining permeability characteristics (Claude, 1978;Briggman et al, 1981;Cereijido et al, 1981). Claude (1978) has suggested that the proportion of "open strands" in a junction more strongly influences junctional permeability than does the total number of sealing strands.…”

“…After replication, the samples were warmed to -3O"C, removed from the vacuum system, and the adhering biological material digested in sodium hypochlorite. Following extensive washing, the samples were recovered on 75-mesh Formvar-coated grids (Bank et al, 1978;Briggman et al, 1981).…”

Ultrastructure of human eccrine sweat glands with special reference to the transitional portion.

“…The human sweat glands have repeatedly been studied with the electron microscope concerning both the secretory portion (HIBBS,1958;IIJIMA,1959;CHARLES, 1960;KURo-SUMI et al, 1960;MUNGER, 1961;ITo and SHIBASAKI, 1966;ELLIS, 1962ELLIS, , 1967ELLIS, , 1968BRIGGMAN et al, 1981) and the duct system (HIBBS,1958;CHARLES, 1960;MUNGER, 1961;213 HASHIMOTO et al, 1966;KUROSUMI, 1977;BRIGGMAN et al, 1981). However, only one paper by SHIBASAKI and ITO (1967) has dealt with the unique portion of the human eccrine sweat gland interposed between the secretory portion and the coiled duct, i.e., the "transitional portion."…”