Fine Structure of the Myoepithelium of the Eccrine Sweat Glands of Man

Abstract

A B S T R A C TThe secretory coils of glutaraldehyde-osmium tetroxide-fixed and Epon-Araldite-embedded eccrine sweat glands from the palms of young men were studied with the electron microscope. The myoepithclial cells lie on the epithelial side of the basement membrane and abut other epithelial elements directly. The irregularly serrated base of the cell has dense thickenings along the plasma membranc which alternate with zones bcaring pits; the smooth apical surface lacks dense thickenings, is studded with pits, and conjoined to secretory cells by cccasional desmosomes. Masses of myofilaments, 50 A in diameter, fill most of the cell and are associated with irregular dense zones. In cross-section the arrangement of the myofilaments seems identical with that of the I band of striated muscle, and the dense zone has typical Z band structure. A few microtubules and cytoplasmic cores bearing profiles of the endoplasmic reticulum, filamentous mitochondria, and glycogen granules penetrate the fibrillar masses and run parallel to the oriented myofilaments. In the perinuclear zone, Golgi membranes, rough-and smooth-surfaced elements of the endoplasmic reticulum, mitochondria, glycogen, microtubules, lipid, pigment, and dense granules are variable components in the cytoplasm. The interrelationships of the myoepithelial cells with the secretory cells suggest that the former may act as regulators, controlling the flow of metabolites to the secretory epithelium. I N T R O D U C T I O NMyoepithelial cells are common components of many vertebrate glands that take their origin from the embryonic ectoderm. They have been studied by cytochemical and the electron microscopic techniques in salivary glands (24,(40)(41)(42)(44)(45)(46); in lacrimal glands (25,26,40); in mammary glands (5,11,15,22,42,44); in the prostate (38); in the Harderian gland (4, 25); and in apocrine) (14,16,19,48) and eccrine (8,13,18,30,32,33 sweat glands. All of these investigators agree that the myoepithelial cells lie on the epithelial side of the basement membrane, and most authors note the similarity between filaments in the cytoplasm of smooth muscle and myoepithelium. The literature shows that although the myoepithelial cells of various glands may differ in size and shape, they are essentially similar in their fine structure. In some glands the contractile function of the myoepithelial elements has been clearly demonstrated (16,27,46) and the similarities in fine structure between the myoepithelial elements of the different glands suggest that they all are contractile cells.In studies seeking the elements basic to all intracellular contractile systems, the organization of every type of contractile cell should be considered. In this respect, striated muscle has been investigated intensively and some progress is now being made in elucidating the structure and function of smooth muscle (21, 34), but for lack of information or from oversight the myoepithelial cell has often 551

Transmission and Scanning Electron Microscopy of the Human Ceruminous Apocrine Gland

“…There are desmosomes at the intercellular bound- aries between the secretory and myoepithelial cells as well as between two adjacent myoepithelial cells as reported by some previous authors (HIBBS, 1958;ELLIS, 1965;TANDLER, 1965;TAMARIN, 1966;KNEELAND, 1966). Hemidesmosomes may occur along the basal myoepithelial surface facing the basal lamina.…”

“…Most research works so far carried out on the fine structure of the myoepithelial cells of various glands have used transmission electron microscopes (TAKAHASHI, 1957(TAKAHASHI, , 1958CHIQUOINE, 1958;BARGMANN and KNOOP, 1959;HOLLMANN, 1959;HAGUENAU, 232 I. KAWABATA and K. KUROSUMI: 1959;KUROSUMI et al, 1959KUROSUMI et al, , 1960SCOTT and PEASE, 1959;LEESON, 1960;ELLIS, 1965;TANDLER, 1965;TAMARIN, 1966;KUROSUMI et al, 1968). These studies demonstrated that the myoepithelial cells rest on the inner surface (epithelial side) of the basal lamina investing the outer surface of the secretory tubules or acini.…”

“…The similarity in fine structure found in myoepithelial cells taken from different glands as well as their similarity to smooth muscle cells suggests that all myoepithelial cells may have the ability to contract (ELLIS, 1965). In order to obtain a comprehensive knowledge of the ultrastructure as well as the three-dimensional arrangement of myoepithelial cells, bath transmission and scanning electron microscopes were used in the present study.…”

“…15) i.e., eccrine glands (KUROSUMI et al, 1960;ELLIS, 1965) and apocrine glands (TAKAHASHI, 1957;KUROSUMI et al, 1959;YAMADA, 1960;BELL, 1974), and also in the lacrimal gland (SCOTT and PEASE, 1959;LEESON, 1960), salivary gland (TAKAHASHI, 1958 a;SCOTT and PEASE, 1959;TANDLER, 1965;TAMARIN, 1966) and mammary gland (LANGER and HUHN, 1958;TAKAHASHI, 1958 a;HAGUENAU, 1959;HOLLMANN, 1959; BARGMANN and KNOOP, 1959; BARGMANN et al, 1961;KUROSUMI et al, 1968 On the contrary, scanning electron microscopy can demonstrate the three-dimensional structure of cells and tissues in a wide range of magnification.…”

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."…”