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  • 1
    ISSN: 1432-1351
    Keywords: Hair cell ; Stimulus transduction ; Cytoskeleton ; Apical membrane ; Electroreception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The receptor cells of the ampullary electroreceptor organs of Ictalurus nebulosus bear microvilli on the apical membrane. Whereas microvilli in mechanoreceptive hair cells and in chemoreceptor cells have a transduction function, the function of these membrane specializations in electroreceptor cells is not fully understood. To study the role of the microvilli of the electroreceptor cells, the ampullary electroreceptor organs were apically exposed to the microfilament-disrupting agents cytochalasin B and D. Electrophysiological measurements showed that cytochalasin caused a high decrease in sensitivity and a slight decrease in spontaneous activity. Exposure to cytochalasin B resulted in a striking disorganization of the microvilli on the apical membrane of the electroreceptor cells. The most plausible explanation for the results is that treatment with cytochalasin mainly affects the actin filaments of the microvilli causing an increase of the resistance of the apical membrane. A high apical resistance results in a decrease of the voltage over the basal membrane, which in turn reduces the sensitivity. The conclusion is that intact apical microvilli are necessary for proper functioning of ampullary electroreceptor organs. Alterations in microvillar properties, like surface area and ion channel conductancy might play a considerable role in the regulation of the sensitivity.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mycopathologia 125 (1994), S. 83-91 
    ISSN: 1573-0832
    Keywords: Colonization ; Computer diskettes ; Fouling ; Fungal isolation ; Magnetic media ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Computer diskettes can be colonized by saprophytic fungi, especially in the humid tropics. Fungi of the generaAlternaria, Aspergillus, Epicoccum, Paecilomyces, Penicillium, andTrichoderma were observed on diskettes from several tropical countries. Common saprophytic fungi from Minnesota colonized clean standard and high density diskettes in growth chambers, indicating that fungal contamination could occur wherever temperature and humidity were adequate.Fusarium species infested diskettes buried in garden soil in Minnesota. Audiotapes, videotapes, and computer magnetic tapes chemically resemble diskettes and also can be colonized by fungi, as can photographic film. The Mylar core of these magnetic media did not support the growth ofPenicillium glabrum, the most aggressive fungus in diskette inoculation studies. However, growth of several fungal species was enhanced when the common plasticizer, lecithin, was added in powdered form to nutrient agar, suggesting that this ingredient of the diskettes may be metabolized by the fungi.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 277 (1994), S. 315-323 
    ISSN: 1432-0878
    Keywords: Amniochorion ; Cryofracture ; Fetal membrane rupture ; Scanning electron microscopy ; Fetal membranes ; Decidua ; Planimetry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract By use of cryofracture and scanning electron microscopy of human amniochorion we have captured images of all the major layers of the tissue. Correlation of confocal and electron-microscope data has allowed greater understanding of how these cellular and acellular layers interconnect in order to maintain their integrity as a multilaminar tissue. This is not straightforward as mutual sliding or area change is required of concentric curved surfaces which expand and contract as does the amnion. In this paper we suggest a mechanism by which the amnion is able to slide with respect to the chorion and still maintain continuity as a structural unit. It is based on the observation of complementary gyri and sulci on surfaces facing the spongy layer which is a shear plane. Cellular detail at higher resolution of the amniotic epithelium and acellular layers provides a more complete description of structural composition than was previously available.
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  • 4
    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Peripolar cell ; Renin ; Juxtaglomerular apparatus ; Scanning electron microscopy ; Mammalia, 12 species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The peripolar cell is a glomerular epithelial cell situated within Bowman's capsule at its vascular pole. It is believed to be a secretory cell which forms part of the juxtaglomerular apparatus. Scanning electron microscopy was used to perform a comparative study of the morphology and number of peripolar cells in twelve mammalian species. The number of renin-secreting cells in kidney sections stained by renin antibodies and immunocytochemistry was counted. There was a marked inter-species variation in the number, size and appearance of peripolar cells. They were largest and most abundant in sheep and goat and fewest in dog, cow and human. There was no correlation between the numbers of peripolar cells and renin-secreting cells. This does not support the view that the peripolar cell is part of the juxtaglomerular apparatus.
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  • 5
    ISSN: 1432-0878
    Keywords: Key words: Kidney ; Glomerulus ; Peripolar cell ; Renin ; Juxtaglomerular apparatus ; Scanning electron microscopy ; Mammalia ; 12 species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The peripolar cell is a glomerular epithelial cell situated within Bowman's capsule at its vascular pole. It is believed to be a secretory cell which forms part of the juxtaglomerular apparatus. Scanning electron microscopy was used to perform a comparative study of the morphology and number of peripolar cells in twelve mammalian species. The number of renin-secreting cells in kidney sections stained by renin antibodies and immunocytochemistry was counted. There was a marked inter-species variation in the number, size and appearance of peripolar cells. They were largest and most abundant in sheep and goat and fewest in dog, cow and human. There was no correlation between the numbers of peripolar cells and renin-secreting cells. This does not support the view that the peripolar cell is part of the juxtaglomerular apparatus.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 278 (1994), S. 419-432 
    ISSN: 1432-0878
    Keywords: Photoreceptor cells ; Endoplasmic reticulum, smooth ; Cytoskeleton ; Actin filaments ; Microtubules ; Polarity ; Calcium ions ; Apis mellifera (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Close to the bases of the photoreceptive microvilli, arthropod photoreceptors contain a dense network of endoplasmic reticulum that is involved in the regulation of the intracellular calcium concentration, and in the biogenesis of the photoreceptive membrane. Here, we examine the role of the cytoskeleton in organizing this submicrovillar endoplasmic reticulum in honeybee photoreceptors. Immunofluorescence microscopy of taxol-stabilized specimens, and electron-microscopic examination of high-pressure frozen, freeze-substituted retinae demonstrate that the submicrovillar cytoplasm lacks microtubules. The submicrovillar region contains a conspicuous F-actin system that codistributes with the submicrovillar endoplasmic reticulum. Incubation of retinal tissue with cytochalasin B leads to depolymerization of the submicrovillar F-actin system, and to disorganization and disintegration of the submicrovillar endoplasmic reticulum, indicating that an intact F-actin cytoskeleton is required to maintain the architecture of this domain of the endoplasmic reticulum. We have also developed a permeabilized cell model in order to study the physiological requirements for the interaction of the endoplasmic reticulum with actin filaments. The association of submicrovillar endoplasmic reticulum with actin filaments appears to be independent of ATP, Ca2+ and Mg2+, suggesting a tight static anchorage.
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  • 7
    ISSN: 1432-0878
    Keywords: Oral mucosa ; Microridges ; Mucous secretory granules ; Coated vesicles ; Cytoskeleton ; Intracellular transport ; Cyprinus carpio (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Superficial cells of the oral mucosal epithelium in the carp and the cytoskeleton of the epithelial cells are examined by scanning and transmission electron microscopy. Microridges are formed on the surface of the epithelium. Epithelial cells contain two types of vesicles: mucous secretory vesicles and coated vesicles. Most of the mucous vesicles are situated in the center of the cell near the Golgi apparatus. In freeze-fracture replicas, intramembranous particles are abundant in the membranes of the secretory vesicles but rare in the apical plasma membrane. Coated vesicles are situated in the apical and subapical cytoplasm. A great number of thick filaments, considered to be keratin filaments, run randomly throughout the cell to form a meshwork. Thick filaments, which are sparse in the central cytoplasm, are connected to the membranes of the secretory vesicles and other membranous organelles. A layer of closely packed thin filaments, considered to be actin filaments, is found just beneath the apical plasma membrane. Microtubules also occur in the apical cytoplasm and run almost parallel to the cell surface. Both kinds of vesicles are connected to the thin and thick filaments. Their functional significance in the regulation of membrane at the free surface is discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 278 (1994), S. 419-432 
    ISSN: 1432-0878
    Keywords: Key words: Photoreceptor cells ; Endoplasmic reticulum ; smooth ; Cytoskeleton ; Actin filaments ; Microtubules ; Polarity ; Calcium ions ; Apis mellifera ; (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Close to the bases of the photoreceptive microvilli, arthropod photoreceptors contain a dense network of endoplasmic reticulum that is involved in the regulation of the intracellular calcium concentration, and in the biogenesis of the photoreceptive membrane. Here, we examine the role of the cytoskeleton in organizing this submicrovillar endoplasmic reticulum in honeybee photoreceptors. Immunofluorescence microscopy of taxol-stabilized specimens, and electron-microscopic examination of high-pressure frozen, freeze-substituted retinae demonstrate that the submicrovillar cytoplasm lacks microtubules. The submicrovillar region contains a conspicuous F-actin system that codistributes with the submicrovillar endoplasmic reticulum. Incubation of retinal tissue with cytochalasin B leads to depolymerization of the submicrovillar F-actin system, and to disorganization and disintegration of the submicrovillar endoplasmic reticulum, indicating that an intact F-actin cytoskeleton is required to maintain the architecture of this domain of the endoplasmic reticulum. We have also developed a permeabilized cell model in order to study the physiological requirements for the interaction of the endoplasmic reticulum with actin filaments. The association of submicrovillar endoplasmic reticulum with actin filaments appears to be independent of ATP, Ca2+ and Mg2+, suggesting a tight static anchorage.
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  • 9
    ISSN: 1432-0878
    Keywords: Key words: Endometrium ; Dehydrogenase ; Cytoskeleton ; Estrous cycle ; Immunocytochemistry ; Immunofluorescence microscopy ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The uteri of German landrace gilts slaughtered at different days of the cycle were processed for immunocytochemistry and biochemical analyses. Plasma was collected for hormone assays. The monoclonal antibody F1 against the structure-bound 17β-estradiol dehydrogenase of porcine endometrial epithelium was applied to rehydrated paraffin sections either as a direct, peroxidase-linked probe or in combination with a fluorescing secondary antibody. The oxidation of estradiol was measured in homogenates of tissue powdered in liquid nitrogen. Immunoreactivity was restricted to endometrial epithelium. In the glandular epithelium, faint dots of fluorescence became visible at day 4, which apparently coalesced to spherical structures of 2-4 μm diameter at the cell basis between days 11 through 17 before disappearing by day 18. A similar distribution was observed for the oxidation products of diaminobenzidine beginning with a faint uniform staining and followed by the appearance of intensely stained basal bodies persisting until day 17. Essentially the same time course was seen in the luminal epithelium but with a different distribution. Immunoreactive material amassed in the apical region of the cells, but the conspicuous aggregations were absent. Time course and intensities of the immunological responses are matched by the enzymatic activity measured in parallel. Both correlate with the plasma progesterone levels, suggesting an induction of the enzyme by the hormone. An involvement of the cytoskeleton in the sequence of subcellular distribution patterns is discussed.
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  • 10
    ISSN: 1432-0878
    Keywords: Brush border ; Actin ; Villin ; Fimbrin ; Brush border myosin-1 ; Cytoskeleton ; Oxynticopeptic cells ; Rana catesbeiana (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The contribution of brush border cytoskeletal proteins (actin, villin, fimbrin, and brush border myosin-1) to organization of the cytoskeletal network underlying apical plications of oxynticopeptic cells was examined by immunohistochemical techniques in frozen sections of gastric mucosa from the bullfrog, Rana catesbeiana. Apical localization of F-actin with phalloidin in oxynticopeptic cells inhibited with cimetidine revealed small, punctate domains within the apical cytoplasm that were consistent with the presence of short microvilli revealed by electron microscopy. Localization of F-actin in cells stimulated with forskolin was limited to a wide continuous band of cytoplasm corresponding to the location of numerous long surface folds. Inhibition of protein synthesis with cycloheximide did not prevent acid secretion or formation of actin filaments within surface folds in stimulated oxynticopeptic cells, suggesting that the formation of filaments does not require actin synthesis. Staining of gastric mucosae with fluorescent DNase-1 demonstrated that oxynticopeptic cells possess an unusually large pool of non-filamentous actin. Taken together, these results suggest that actin-filament formation in stimulated cells occurs by polymerization of an existing pool of non-filamentous actin. Localization of antibodies specific for villin and fimbrin revealed that these proteins were present within intestinal absorptive cells and gastric surface and neck cells but were not present within inhibited or stimulated oxynticopeptic cells. Brush border myosin-1, present in intestinal absorptive cells, was not present in gastric epithelium. Thus, we propose that actin-containing projections in oxynticopeptic cells are not organized like intestinal microvilli and that filament formation occurs after stimulation by modulating intracellular pools of filamentous and non-filamentous actin.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 275 (1994), S. 225-234 
    ISSN: 1432-0878
    Keywords: Compound eye ; Photoreceptor cells ; Ion pumps ; Polarity ; Spectrin ; Cytoskeleton ; Immunocytochemistry ; Calliphora erythrocephala (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Na,K-ATPase (sodium pump) plays a central role in the physiology of arthropod photoreceptors as it re-establishes gradients for Na+ and K+ after light stimulation. We have mapped the distribution of the Na,K-ATPase in the photoreceptors of the blowfly (Calliphora erythrocephala) by immunofluorescent and immunogold cytochemistry, and demonstrate that the distribution pattern is more complex than previously presumed. High levels of sodium pumps have been detected consistently in all photoreceptors R1-8 on the nonreceptive surface, but no sodium pumps are found on the microvillar rhabdomere. Within the nonreceptive surface of the cells R1-6, however, the sodium pumps are confined to sites juxtaposed to neighboring photoreceptor or glial cells; no sodium pumps have been detected on the parts of the nonreceptive surface exposed to the intra-ommatidial space. In R7 and R8, the sodium pumps are found over the entire nonreceptive surface. The cytoskeletal protein spectrin colocalizes with the sodium pumps suggesting that linkage of the pump molecules to the spectrin-based submembrane cytoskeleton contributes to the maintenance of the complex pattern of pump distribution.
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  • 12
    ISSN: 1432-0878
    Keywords: Endometrium ; Dehydrogenase ; Cytoskeleton ; Estrous cycle ; Immunocytochemistry ; Immunofluorescence microscopy ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The uteri of German landrace gilts slaughtered at different days of the cycle were processed for immunocytochemistry and biochemical analyses. Plasma was collected for hormone assays. The monoclonal antibody F1 against the structure-bound 17β-estradiol dehydrogenase of porcine endometrial epithelium was applied to rehydrated paraffin sections either as a direct, peroxidase-linked probe or in combination with a fluorescing secondary antibody. The oxidation of estradiol was measured in homogenates of tissue powdered in liquid nitrogen. Immunoreactivity was restricted to endometrial epithelium. In the glandular epithelium, faint dots of fluorescence became visible at day 4, which apparently coalesced to spherical structures of 2–4 μm diameter at the cell basis between days 11 through 17 before disappearing by day 18. A similar distribution was observed for the oxidation products of diaminobenzidine beginning with a faint uniform staining and followed by the appearance of intensely stained basal bodies persisting until day 17. Essentially the same time course was seen in the luminal epithelium but with a different distribution. Immunoreactive material amassed in the apical region of the cells, but the conspicuous aggregations were absent. Time course and intensities of the immunological responses are matched by the enzymatic activity measured in parallel. Both correlate with the plasma progesterone levels, suggesting an induction of the enzyme by the hormone. An involvement of the cytoskeleton in the sequence of subcellular distribution patterns is discussed.
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  • 13
    ISSN: 1059-910X
    Keywords: Matrix ; Membrane ; SEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The three-dimensional organization of the internal compartments of conventionally fixed and embedded rat-liver mitochondria has been determined by tomographic reconstruction from tilt-series images collected on the Albany high-voltage electron microscope. The results indicate that the inner membranes of these organelles are predominantly tubular in the orthodox (expanded matrix) conformation, as previously suggested by scanning electron microscopy. In the condensed (contracted matrix) conformation, the intracristal space opens up into large irregularly shaped compartments which are connected to each other and to the external (intermembrane) space by tubes with approximately the same diameter (20 nm) as those observed in the orthodox state. These results raise several questions, in particular about the nature of the structural transitions that occur in the cristae during matrix expansion and contraction, and about the influence of inner-membrane shape on the diffusion of ions and metabolites between the intracristal and intermembrane compartments. © 1994 Wiley-Liss, Inc.
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  • 14
    ISSN: 1059-910X
    Keywords: Lymphoma ; Splenomegaly ; SEM ; TEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Peripheral blood mononuclear cells (PBLs) from 14 patients with low grade non-Hodgkin's B-cell lymphomas with predominant splenomegaly were studied by means of scanning (SEM) and transmission electron microscopy (TEM). All patients had peripheral blood and bone marrow involvement, the absence of lymphoadenopathy, and, except in one case, immunophenotypic features of a malignant proliferation of mature spleen B-cells arising from outside the germinal center, but not consistent with CLL or HCL. Several distinctive cytological features were observed in PBLs of the different subgroups. The SEM surface features of PBLs in patients with intermediate differentiation lymphocytic lymphoma (IDL) (five cases), lymphoplasmacytoid immunocytoma (LP-IC) (two cases), and mixed small and large cells malignant lymphoma (one case) were characterized by the presence of numerous well-developed microvilli. Some distinctive TEM ultrastructural features were also seen in the different cases. In the two cases of splenic lymphoma with villous lymphocytes (SLVL), SEM revealed large and elongated surface microvilli generally arising from two or three poles of the cells. This surface morphology, confirmed by TEM analysis, may be pathognomonic of this disease. Four additional cases, tentatively classified as small lymphocytic lymphoma on the basis of immunophenotypic data, were extremely heterogeneous at both SEM and TEM analysis. The ultrastructural features revealed by SEM and TEM may be useful for the more precise characterization of this heterogenous group of diseases, which is generally difficult to define even when immunophenotypic and molecular approaches are used. © 1994 Wiley-Liss, Inc.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 108-124 
    ISSN: 1059-910X
    Keywords: Cytoskeleton ; Steroidogenesis ; Mitochondrial development ; Gap junctions ; Haras Oncogene ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Granulosa cells, which nurse the oocyte and serve as a major source for estradiol and progesterone production, undergo major morphological changes which correlate very well with modulation of their steroidogenic capacity. These include changes in intercellular contacts and communication, in cell membrane receptors, and in the development and organization of organelles associated with steroidogenesis (i.e., mitochondria, smooth endoplasmic reticulum, lipid droplets, and lysosomes). These biochemical and morphological changes can also be obtained in primary cultures as well as in oncogene transformed granulosa cell lines established recently in our laboratory. A growing body of evidence suggests that plasticity of the cytoskeleton plays a major role in the biochemical and morphological differentiation of granulosa cells as well as in other steroidogenic cells. © 1994 Wiley-Liss, Inc.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 67-74 
    ISSN: 1059-910X
    Keywords: Al coating ; Frozen hydrated specimens ; Gels ; Longitudinal sections ; Microanalysis ; Morphometric analysis ; Plant tissues ; SEM ; Serial sections ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A procedure is described for forming a flat face on a frozen piece of plant tissue, which may then be observed fully-hydrated or lightly etched, and coated or uncoated with a metal film, in scanning electron microscopy (SEM). The frozen sample was planed with a glass knife at -80°C in cryo-ultramicrotome. The sections were discarded, and the planed block face placed on the cold stage in the microscope column, either for observation uncoated at low kV, or for light etching (-90°C) to reveal the cell outlines. If a higher accelerating voltage was needed, the face was given an evaporative coating of Al in the cryo-preparation chamber and returned to the column. The advantages of the planed face over the usual fracture face are illustrated: imaging at a chosen rather than a chance position; clearer cellular and subcellular detail; preservation of hydrated gels like mucilage and swollen cell walls; the possibility of making serial parallel sections through the same piece of tissue; opportunities for accurate morphometric analyses on the planed face; capacity to produce longitudinal sections; preservation of very delicate structures that are destroyed by fixation and drying. A major advantage of the Al-coated planed face is the increased accuracy of energy-dispersive X-ray (EDX) microanalyses on a smooth rather than a rough surface. Tests are included which show that neither the light etching employed, nor successive planing, interferes with the analyses of elements in the frozen face. © 1994 Wiley-Liss, Inc.
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  • 17
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 27 (1994), S. 429-438 
    ISSN: 1059-910X
    Keywords: Biological pattern formation ; Cuticle ; Thin-film ; Lattice ; Scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: All butterfly and moth scales and bristles are made of non-living insect cuticle. Each is the product of a single epithelial cell, and all share the same basic architecture. However, some are highly specialized, and their cuticle is further elaborated into stacks of thin-films, lattices, or other minute structures, many of which first came to our attention because they interact, with light to produce structural colors. The scale cell forms the scale by extruding a projection of itself and secreting around it the outer epicuticle, a thin cuticular envelope which will form the outermost layer of the scale. The inner layers of cuticle, collectively called the procuticle, are secreted thereafter and go on to form the lattices, pillars, or other internal structures of the scale. We believe that the pattern-forming mechanisms used by the cell to shape the cuticle into its finished form include elastic buckling of the outer epicuticle to produce external folds, and “masking” of certain areas of the original epicuticular envelope to produce thin spots which will break through to become windows. Varied though they be, all insect cuticular patterns have common basic elements, which suggests that our findings may be generalized to other highly patterned insect cuticles, particularly those formed by single cells. © 1994 Wiley-Liss, Inc.
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  • 18
    ISSN: 1059-910X
    Keywords: NK cells ; Neutrophils ; Fcγ receptor ; Immunogold ; SEM ; Backscattered electron imaging ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Human natural killer cells and polymorphonuclear neutrophils constitutively express the low-affinity IgG Fc receptor (FcγRIII, CD16 molecule). To investigate cell surface morphology, antigenic receptor density, and topographical distribution of FcγRIII on the plasma membrane of natural killer cells and polymorphonuclear neutrophils, conventional scanning electron microscopy (SEM), flow cytometry, and immunoscanning electron microscopy were used. FcγRIII was detected with an indirect immunogold labeling procedure, and receptors were visualized in the backscattered and secondary electron imaging mode of SEM. Natural killer cells showed a cell surface morphology compatible with lymphocytic differentiation characterized by microvilli and microridges. Polymorphonuclear neutrophils showed surface features characterized by ridges with folds and scattered short microvilli. Natural killer cells displayed a lower cell labeling density, whereas polymorphonuclear neutrophils showed a high level of expression of FcγRIII on the plasma membrane by quantitative analysis with SEM in the backscattered electron imaging mode. Flow cytometry analysis confirmed these findings. Analysis of the topographical distribution of FcγRIII antigenic receptor sites by SEM in the backscattered and secondary electron imaging modes showed that FcγRIII on natural killer cells are randomly distributed, whereas FcγRIII are located on ridges and folds of the plasma membrane of polymorphonuclear neutrophils. These observations suggest that natural killer cells and polymorphonuclear neutrophils differ in their levels of expression and topographic distribution of FcγRIII on the plasma membrane. This different spatial distribution of FcγRIII would provide morphological evidence of certain cellular functions mediated by natural killer cells and polymorphonuclear neutrophils. © 1994 Wiley-Liss, Inc.
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  • 19
    Electronic Resource
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    Microscopy Research and Technique 29 (1994), S. 411-431 
    ISSN: 1059-910X
    Keywords: Corrosion casts ; LM ; SEM ; TEM ; Microvasculature ; Ultrastructure ; Absorption ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The aim of the present study was to provide a comprehensive morphological analysis of the porcine epididymis in view of the specific functions being performed in different regions of this organ. Blood supply and microvasculature of efferent ductules and epididymal duct were investigated by means of corrosion casts which were analysed macroscopically and by scanning electron microscopy. This revealed blood supply to the testis and epididymis to be closely related. The capillary pattern was typical for the efferent ductules, the caput, corpus, and distal cauda epididymidis, respectively. Corrosion casts were also used to visualize the course of the efferent ductules themselves. Tissue samples from different regions of the efferent ductules and epididymal duct were examined by light microscopy and both scanning and transmission electron microscopy, with special attention being payed to transitional areas. Morphological criteria allowed the distinction of three segments within the efferent ductules and of the initial segment, proximal caput, distal caput, corpus, proximal cauda, and distal cauda regions of the epididymal duct. Components of the endocytic apparatus of efferent ductule principal cells were identified by ferritin uptake. Ultrastructural evidence of absorption in the epididymal duct was particularly prominent in proximal and distal caput. Extensive cisternae of rough endoplasmic reticulum and a well-developed Golgi apparatus were indicative of active protein synthesis and secretion especially in the distal caput and corpus regions. However, assignment of various organelles in principal cells of the epididymal duct to either absorptive or secretory pathways still remains tentative. © 1994 Wiley-Liss, Inc.
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  • 20
    Electronic Resource
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    Microscopy Research and Technique 27 (1994), S. 134-144 
    ISSN: 1059-910X
    Keywords: Oogenesis ; Cytoskeleton ; Embryogenesis ; Somatic cells ; Cytoskeletal sheets ; Cytokinesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Mammalian oogenesis is a process which requires a variety of changes in the structure and function of the specialized female germ cell. Evidence suggests that the cytoskeleton may mediate several of these structural and functional changes. In this review we evaluate what is known of cytoskeletal function during oogenesis, with emphasis on specialized cytoskeletal features in mammals. Existing investigations suggest that the oocyte, as a highly specialized cell, contains unique cytoskeletal elements which exhibit functions restricted to the process of early development. © 1994 Wiley-Liss, Inc.
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  • 21
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 286-296 
    ISSN: 1059-910X
    Keywords: RBC ; SEM ; Colloidal gold ; Silver enhancement ; Double labeling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The majority of mouse monoclonal antibodies reacting with blood group epitopes on erythrocytes are of the IgM class, have equal light chain type, and are available as culture supernatants only. To study the interrelationship of the blood group antigens, a method is presented which allows double labeling applying two unconjugated monoclonal antibodies of the same class and species. The method comprises two indirect, sequential labelings using mouse IgM anti-A and anti-H as primary antibodies and two goat anti-mouse IgM conjugated to 30 and 20 nm colloidal gold particles as secondary antibodies. After labeling for the first antigen, free binding sites on the primary antibody are blocked by incubation with an unconjugated goat anti-mouse antibody. The free anti-species on the secondary antibody, conjugated to 30 nm gold particles, are inactivated by silver enhancement. The silver enhancement also enlarges the gold particle for optimal discrimination between the two particle sizes, which are chosen accordingly. Semiquantitations of double labeled cells from subgroup A2 and A3 were found to be in good agreement with the counts of the corresponding single labelings as well as between experiments, irrespective of which of the two antibodies was applied in the first labeling sequence. The results were in accordance with a reciprocal but nonlinear relationship between the A and H antigens and suggest different affinities of the two antibodies for the epitopes in the subgroups investigated, indicating different biochemistry of the antigen determinants. © 1994 Wiley-Liss, Inc.
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  • 22
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    Microscopy Research and Technique 27 (1994), S. 25-45 
    ISSN: 1059-910X
    Keywords: Transmission electron microscopy ; Scanning electron microscopy ; Histochemistry ; Cytokeratins ; Microfilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In salivary glands and other exocrine organs, there are starfish-shaped cells that lie between the basal lamina and the acinar and ductal cells. These have structural features of both epithelium and smooth muscle cells, and so are called myoepithelial cells. Their functions include contraction when the gland is stimulated to secrete, compressing or reinforcing the underlying parenchymal cells, thus aiding in the expulsion of saliva and preventing damage to the other cells. They also may aid in the propagation of secretory and other stimuli. Their common developmental origin with the basal cells of the larger ducts is displayed in the mature glands by shared structural and immunohistochemical features, but most such basal cells do not have the distinguishing features of myoepithelial cells, such as myofibrils. Although myoepithelial cells can be identified by light microscopy through enzyme histochemistry and special stains and immunohistochemistry for their myofibrils, these techniques can be misleading in salivary gland neoplasms. Thus, the most reliable means of identifying neoplastic myoepithelial cells is with a combination of histochemistry and electron microscopy. The extent to which these cells are derived from undifferentiated stem cells in both normal and neoplastic growth is controversial. The presentation here of transmission electron microscopy (TEM) of well-differentiated myoepithelial cells in mitotic division indicates that stem cells are not necessarily the only source of myoepithelial cells in the later stages of salivary gland development or in neoplasia. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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  • 23
    ISSN: 1059-910X
    Keywords: B Lymphocytes ; AIDS ; HIV ; Immunodeficiency ; Scanning electron microscopy ; SIV ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The ultrastructural features of AA-2 cells infected with either of two strains of simian immunodeficiency virus (SIVMne-E11S or SIVSMM-PBj) were examined by scanning electron microscopy (SEM). Transformed CD4+ human B lymphocytes (AA-2) were inoculated with SIV and observed at 2, 4, and 7 days post-inoculation (dPI). Infected AA-2 cells were distinguished by the progressive loss of microvilli, and variable numbers of free or protruding spherical particles measuring 90-120nm in diameter along the cell surface. Syncytial cell formation (complexes of fused cells) and necrotic cells were evident at each time point with the most numerous observations at 7 dPI. While the distribution and severity of the viral induced changes increased with time and affected virtually all cells by 7 dPI, the alterations were detected sooner and were more pronounced in SIVSMM-PBj infected cells. This finding is consistent with the in vivo data from primate studies using the same strains of SIV. Syncytial cells exhibited slight to moderate indentations which appeared to coincide with the boundaries of individual cells forming the complex. The plasma membrane of syncytial cells was relatively smooth and lacked microvilli. Spherical particles and buds protruding from the plasma membrane were predominate features of syncytial cell surfaces. By the employment of antisera generated against whole SIVMne-E11S, both transmission and scanning immunoelectron microscopy confirmed the identity of the spherical structures as free and budding SIV virions. © 1994 Wiley-Liss, Inc.
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  • 24
    ISSN: 1432-0827
    Keywords: Amelogenesis ; Enamel structure ; Enamel pathology ; Rat incisor ; Bisphosphonate ; HEBP ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A single, high dose of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) results in three different types of lesions along the enamel surface of the rat incisor, one of which is seen as a “bright band” crossing the final enamel surface in the scanning electron microscope (SEM). The present study presents the structural surface features of final enamel formation and its subsequent maturation in normal and HEBP-exposed rats. The position of the bright band is examined in relation to where the Tomes processes pits disappear (DTPP), where the boundary between “light” and “dark” enamel (LDB) as seen by SEM is located, and in particular, where the socalled opaque boundary (OB) is positioned. Groups of rats were given a subcutaneous dose of 0, 5, or 10 mg P/kg body wt of HEBP and killed at intervals of either 12 hours or 2 or 9 days. The mandibular incisors were processed for SEM after enzymatic digestion of enamel organ remains. Enamel surface nodules, 100–300 nm in diameter and composed of smaller units, were evident at the start of final enamel formation which was defined as the area from DTPP to LDB. With increasing maturation, the nodules merged to form a smooth surface. In HEBP-treated animals, growth and merging of these surface nodules became arrested at the time of injection resulting in an irreversible “porous” stage corresponding to that part of the surface enamel. This area—the bright band—developed corresponding to the start of the area of final enamel formation and was subsequently carried incisally during the eruption of the incisor. Adjacent surface areas appeared normal, with densely packed nodules in the maturation stage. The bright band did not coincide with either LDB or OB at the time of injection as these landmarks were located about 105 and 2000 μm incisally to DTTP, respectively. The width of the bright band was dose dependent (78 μm versus 105 μm at 5 and 10 mg P/kg body wt) which may indicate that HEBP carries on its effect in a few hours after administration. The findings are most likely a result of HEBP's physicochemical effect directly on crystal growth, although a cellular effect cannot be excluded.
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  • 25
    ISSN: 1432-0827
    Keywords: Osteoclast ; Bone resorption ; Cytochalasin D ; Cytoskeleton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The osteoclastic cytoskeleton has been demonstrated to be composed of microfilaments. Osteoclastic multinucleated cells were suspended on dentine slices and cultured for 24 hours in the presence or absence of cytochalasin D (CD), a specific and potent inhibitor of actin filament elongation to determine the role of this cytoskeleton. Cultured cells and co-cultured dentine slices were examined ultrastructurally. Unlike those in control cultures without CD, osteoclasts in CD-treated cultures became spherical in shape and lacked microvilli on their basolateral cell surfaces. Most importantly, CD treatment induced a complete disappearance of the ruffled border-clear zone complexes in osteoclasts, which resulted in loss of osteoclast-cytoplasmic polarity. Morphometric analysis of backscattered electron micrographs of co-cultured dentine slices revealed that CD treatment strongly inhibited the formation of resorption lacunae in a dose-dependent manner. These results suggest that the cytoarchitecture, as well as the bone-resorbing function, of the osteoclast is highly regulated by the F-actin-containing microfilamentous cytoskeleton in the ruffled border-clear zone complex.
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  • 26
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    Journal of comparative physiology 173 (1993), S. 801-807 
    ISSN: 1432-1351
    Keywords: Catfish larvae ; Visual pigments ; Photoreceptors ; Microspectrophotometry ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The retinal photoreceptors from larval channel catfish (Ictalurus punctatus) were studied using single cell, in situ microspectrophotometry. Rods appear at 5 days after hatch; cones are present from day one. The rods contain a visual pigment which absorbs light maximally at 540 nm. The cones contain either a green sensitive visual pigment with peak absorbance at 535 nm or a red sensitive visual pigment with peak absorbance at 608 nm. All pigments are based on vitamin A2. Visual pigment complement does not change with age, as photoreceptors from adultI. punctatus, I. catus andI. melas contain visual pigments virtually identical to those of the larvalI. punctatus. Regardless of age, no visual pigment with peak absorbance in the short wavelength region of the spectrum was ever observed. Scanning electron microscopy of adultI. punctatus retinas showed large rods with long, cylindrical outer segments and smaller cones with short, tapered outer segments. The myoids of both rods and cones are extensable. The rods, embedded in a granular tapetal material, comprise from 50 to 60% of the photoreceptors. Only single cones are present. The data are consistent with the idea that the ictalurid catfishes spend their entire lives in an environment deficient in blue light.
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  • 27
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Retinular cells ; Compound eyes ; Microtubules ; Microtubule polarity ; Pigment granule migration ; Actin ; Gonodactylus oerstedii (Crustacea, Stomatopoda)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Retinular cells of the compound eyes of stomatopods (mantis shrimps) contain screening pigment granules that migrate radially in response to light. To clarify the role of the cytoskeleton in these movements, we have performed light microscopy and ultrastructural analyses of cytoskeletal organelles in retinular cells. Rhodamine phalloidin staining indicates that filamentous actin is a component of microvillar rhabdomeres and zonula adherens between retinular cells. Ultrastructural studies reveal three populations of microtubules in retinular cells that differ in their orientations and labilities to fixation. Two of these populations are oriented longitudinally in cells: the soma microtubules, found primarily in a column in the cell soma, and the more labile palisade microtubules, which extend alongside the palisade vacuole near the rhabdomere. The third, most labile microtubule population, and filaments 9–30 nm in diameter, are oriented radially in retinular cells, some within cytoplasmic bridges that span the palisade. The radial microtubules and filaments are appropriately oriented for participating in pigment granule migration. Determination of microtubule polarities in retinular cells by decoration with endogenous tubulin indicates that palisade and soma microtubules contain subpopulations having opposite polarity orientations, as has been observed in neuronal dendrites. In contrast, neighboring pigment cells contain microtubules uniformly oriented with minus ends towards the nucleus, as has been observed in most cell types studied.
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  • 28
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    Cell & tissue research 272 (1993), S. 575-578 
    ISSN: 1432-0878
    Keywords: Pineal complex ; Frontal organ ; Development, ontogenetic ; Scanning electron microscopy ; Hynobius dunni (Urodela)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The pineal complex of larval and adult salamanders, Hynobius dunni, was examined by light and scanning electron microscopy. This pineal complex displays an anterior and a posterior portion, both of which possess a lumen. The anterior lumen is small and closed, whereas the posterior lumen is in open communication with the third ventricle. Cell processes of the photoreceptor cells and microvilli of the supportive cells are visible in both lumina. The anterior part of the complex is formed by an independent, second evagination from the common pineal anlage; this process takes place immediately after hatching. The anterior body of the pineal complex of H. dunni appears to be homologous to the frontal organ of anurans.
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  • 29
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    Cell & tissue research 273 (1993), S. 107-117 
    ISSN: 1432-0878
    Keywords: Heart ; Endocardial endothelium ; Cytoskeleton ; Actin ; Confocal scanning laser microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The cytoskeleton in endocardial endothelium of rat heart was examined by en face confocal scanning laser microscopy. In the ventricular cavity, endocardial endothelial cells had a polygonal shape and F-actin staining was generally restricted to the peripheral junctional actin band. Central F-actin bundles, or stress fibers, in endocardial endothelial cells were found on the tendon end of papillary muscles, especially in the right ventricle, and frequently in the outflow tract of both ventricles; elsewhere, stress fibers were scarce. Many endocardial endothelial cells were elongated in areas of endothelium with stress fibers, but no correlation was found between cell elongation and the number of stress fibers. An inverse correlation was found between the number of stress fibers and the surface area of endocardial endothelial cells. Shear stress as well as mechanical deformation of the surface of the ventricular wall during the cardiac cycle may affect cell shape and the organization of actin filaments in endocardial endothelial cells. Vimentin in endocardial endothelial cells formed a filamentous network with some distinct cytoplasmic and juxtanuclear vimentin bundles. No perinuclear ring of vimentin filaments was observed in endocardial endothelium. Microtubules in endocardial endothelial cells were, in contrast to endothelial cells of rat aorta, not aligned, less closely packed and originated from randomly distributed centriolar regions. The cytoskeleton has been suggested to play an important role in cellular functions of vascular endothelial cells. Accordingly, differences in the cytoskeletal organization between endocardial and vascular endothelial cells may relate to differences in functional properties.
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  • 30
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    Cell & tissue research 274 (1993), S. 127-133 
    ISSN: 1432-0878
    Keywords: Spectrin ; Cytoskeleton ; Isoforms ; Heart ; Immunocytochemistry ; Western blotting ; Mouse (C57BL/6)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of two isoforms of spectrin in the adult mouse heart was investigated by Western blotting and immunocytochemistry by use of monospecific antibodies to erythrocyte spectrin and nonerythroid brain spectrin (240/235). Western blotting revealed proteins analogous to both isoforms of α-spectrin in adult heart. Light-microscopic immunocytochemistry indicated that erythroid spectrin was distributed throughout the myocardium, with immunofluorescence localized to plasma membranes, Z-lines, and intercalated discs. Antibodies to brain spectrin (240/235) exhibited staining throughout the heart, with a generally diffuse distribution except for the prominent immunoreactivity associated with the intercalated discs. Nonerythroid spectrin immunofluorescence was detected in the endothelial cells of the endocardium and the mesothelial cell lining of the epicardium. Erythrocyte spectrin was not detected in the endocardium or the epicardium. The identification and localization of spectrin isoforms in the mammalian heart suggest the importance of spectrin proteins in the structural integrity and proper function of cardiac cells and tissues. This is the first demonstration of two different α-spectrin subunits in the mammalian heart.
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  • 31
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    Microscopy Research and Technique 25 (1993), S. 503-508 
    ISSN: 1059-910X
    Keywords: Intermetallic compounds ; ESEM ; SEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Copper samples, hot solder (eutectic) dipped and thermally aged, were cross-sectioned and placed in an environmental scanning electronic microscope (ESEM). While in the ESEM the samples were heated for ∼ 2.5 h at 170°C to stimulate the growth of additional Cu/Sn intermetallic compound. The intent of the study was to obtain a continuous real-time videotape record of the diffusion process and compare the observations to static SEM images reported to represent long-term, naturally aged intermetallic growth. The video obtained allows the observation of the diffusion process and relativistic growth phenomena at the Cu, Cu3Sn, Cu6Sn5, and solder interfaces as well as effects on the bulk Cu and solder. Effects contrary to earlier reports were observed; for example, growth rates of Cu3Sn were found to greatly exceed those of Cu6Sn5. © 1993 Wiley-Liss, Inc.
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  • 32
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    Microscopy Research and Technique 26 (1993), S. 260-271 
    ISSN: 1059-910X
    Keywords: Cytoskeleton ; Microtubules ; Intermediate filaments ; Membranous organelles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Kidneys of anesthetized rats were perfused with digitonin to extract cytosolic proteins of glomerular podocytes so that the remaining intracellular structures could be examined by three-dimensional stereo high-resolution scanning electron microscopy (HRSEM). Cytoskeleton, consisting of microtubules and intermediate filaments, was preserved with each applied concentration of digitonin. High concentrations of digitonin (1.0 mg/ml) produced a corrugated appearance in plasma membranes likely due to the formation of digitonin-cholesterol complexes. At 1.0 mg/ml digitonin, the Golgi complex became vesicularized, and mitochondria were well extracted and their ultrastructure preserved. Lower concentrations of digitonin (0.1 and 0.2 mg/ml) were less disruptive to both the plasma membrane and the Golgi complex. Mitochondria, rough endoplasmic reticulum, coated vesicles, nuclear membrane, and chromatin were well preserved. Extraction with digitonin, at the optimal concentration and perfusion time, simultaneously maintains both the cytoskeleton and membranous organelles inside the cell and provides a method to elucidate the interactions between these two components. Furthermore, digitonin extraction should preserve antigenic sites, thereby allowing the localization of intracellular proteins by backscattered electron imaging of immunogold labels in the scanning electron microscope. © 1993 Wiley-Liss, Inc.
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  • 33
    ISSN: 1059-910X
    Keywords: Image analysis ; Respiratory cells ; SEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This paper describes the coupling between a scanning electron microscope (SEM) and an image analysis workstation. The system was designed in order to drive the SEM and to analyse any sample. It allows automatic (edge detection) or semiautomatic (pointing, marking, drawing) object detection. Two types of data can be obtained: (1) topographical information, such as the location of the object within a region of interest drawn at any magnification of the microscope, or (2) quantitative data, such as morphometric characteristics of objects. In addition, high resolution maps of the section, regions of interest, and objects can be obtained with a laser printer. This software was first applied to quantitate the adhesion of the bacteria Pseudomonas aeruginosa to human respiratory epithelial cells in culture. P. aeruginosa was shown associated with ciliated cells. The second application concerned the study of the distribution of specific carbohydrate residues at the surface of the respiratory cells. The gal residues were revealed using the lectin Ricinas communis agglutinin II, adsorbed to colloidal gold particles. A relationship between the presence of adherent bacteria and labelling was shown. © 1993 Wiley-Liss, Inc.
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    Microscopy Research and Technique 26 (1993), S. 133-141 
    ISSN: 1059-910X
    Keywords: Taste ; Secretion ; Microvilli ; Freeze-substitution ; Freeze-fracture deep-etching ; Electron microscopic cytochemistry ; Colloidal gold ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Thaumatin is a protein that tastes intensely sweet only to Old World monkeys and to higher primates, including man. Here we used pre-embedding ultrastructural methods to study the distribution of thaumatin in apical regions of Rhesus monkey foliate papillae, using thaumatin conjugated to 5 nm gold particles. With freeze-substitution we saw that gold-labeled thaumatin bound to an electron-opaque, sponge-like secretory substance inside the taste bud pores. Labeled thaumatin was found at the surface of the secretory substance even deep inside the pore, where other, unlabeled cellular structures surrounded the substance. With freeze-fracture deep-etching the secretory substance that bound the thaumatin-gold particles appeared coarsely granular. There was no labeling of any other taste bud pore structure, including microvilli and small membranelined vesicles. Pre-incubation with an excess of unlabeled thaumatin inhibited binding with goldlabeled thaumatin. The results suggest that the secretory substance had the greatest affinity of all taste pore structures to the sweet-tasting compound under our experimental conditions. Therefore, gustatory reception probably involves various taste compound binding structures, microvilli, and also secretory substances like the one described here which bound thaumatin. We speculate that the secretory substance may bind taste stimuli and serve as an intermediate between stimuli and receptors. It could be involved in stimulus removal or delivery or both. © 1993 Wiley-Liss, Inc.
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  • 35
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    Cell & tissue research 268 (1992), S. 71-79 
    ISSN: 1432-0878
    Keywords: Photoreceptor cells ; Cytoskeleton ; Actin filaments ; Endoplasmic reticulum, smooth ; Apis mellifera (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fluorescent phallotoxins and heavy meromyosin were used to reveal the organization of the actin cytoskeleton in honeybee photoreceptor cells, and the relationship of actin filaments to the submicrovillar, palisade-like cisternae of the endoplasmic reticulum (ER). Bundles of unipolar actin filaments (pointed end towards the cell center) protrude from the microvillar bases and extend through cytoplasmic bridges that traverse the submicrovillar ER. Within the cytoplasmic bridges, the filaments are regularly spaced and tightly apposed to the ER membrane. In addition, actin filaments are deployed close to the microvillar bases to form a loose web. Actin filaments are scarce in cell areas remote from the rhabdom; these areas contain microtubule-associated ER domains. The results suggest that the actin system of the submicrovillar cytoplasm shapes the submicrovillar ER cisternae, and that the distinct ER domains interact with different cytoskeletal elements.
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  • 36
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    Cell & tissue research 270 (1992), S. 353-363 
    ISSN: 1432-0878
    Keywords: Eye, compound ; Glia-like cells ; Pigment cells ; Cytoskeleton ; Actin filaments ; Spectrin ; Microtubules ; Apis mellifera (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The organization of the submembrane cytoskeleton of non-photoreceptive, accessory cells in the honeybee compound eye was examined using light-microscopic (phallotoxin labeling, immunohistochemistry) and electron-microscopic (decoration with myosin fragments) techniques. The crystalline cone cells contain numerous peripheral actin filaments oriented longitudinally with antiparallel polarity. Bundles of microtubules lie under the plasma membrane of primary pigment cells, in close apposition to the crystalline cone; they are interspersed with only a few actin filaments. Pigmented glial cells (secondary pigment cells) contain a two-dimensional filament/particle web lining their entire plasma membranes. Both filamentous actin and α-spectrin are localized within the cortex of these cells, indicating that they are web components. The results demonstrate that the three cell types contain different cortical cytoskeletons, implying different functional properties.
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  • 37
    ISSN: 1432-0878
    Keywords: Adrenal gland ; Cell culture ; ACTH ; Ageing ; Corticosteroid ; Cytoskeleton ; Domestic mallard, embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological and functional changes associated with ageing were studied in adrenal steroidogenic cells derived from duck embryos. Cells grown for not more than three days had structural characteristics similar to their counterparts in vivo; they contained numerous lipid droplets and mitochondria, an abundant smooth edoplasmic reticulum, an even network of microtubules, and microfilaments that formed extensive and elaborate systems of parallel stress fibers. After the 3rd day of growth in culture, many of the cells started to decrease in size and become elongated; the older cells showed less well-defined actin filaments and contained elongated mitochondria, fewer lipid droplets, less smooth endoplasmic reticulum, and swollen cisternae of rough endoplasmic reticulum. The proliferative capacity of the cells was the same when they were cultured in either the presence or the absence of 1–24 ACTH. After the first day of growth in culture, the steroidogenic capacity of the cells declined and the addition of 1–24 ACTH to the growth medium did not prevent changes in their structure and function. The decline in steroidogenic capacity occurred both in terms of the amount of hormone released into the culture medium and in the ability of the cells to respond when incubated in buffer containing 1–24 ACTH. Since the basal unstimulated rates of corticosteroid production also declined as the cells aged, it is probable that the steroidogenic deficiency occurs at a site distal to the corticotropin receptor; this is also consistent with the ultrastructural observations that suggest a relationship between the morphological changes and the decline in steroidogenic capacity as the cells age.
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  • 38
    ISSN: 1432-0878
    Keywords: ACTH ; Actin ; Adrenal gland ; Cell culture ; Corticosterone ; Cytoskeleton ; Steroidogenesis ; Tubulin ; Development, ontogenetic ; Domestic mallard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cells derived from the adrenal glands of duck embryos immediately prior to hatching were grown in culture and used to study the morphological and cytoskeletal changes and steroidogenic responses induced by 1–24 ACTH. Changes in the cytoskeletal components were observed by rhodamine-phalloidin staining for actin and by staining the tubulin immunoreactive components with FITC. The cultures were comprised of a small population of chromaffin cells and a larger population of steroidogenic cells. The chromaffin cells were distinguished by their tyrosine hydroxylase immunoreactivity. The steroidogenic cells were characterized by the presence of sudanophilic lipid droplets, numerous mitochondria, abundant smooth endoplasmic reticulum, microtubules distributed as a fairly even network throughout the cytoplasm, and microfilaments that formed an extensive and elaborate system of stress fibers with many parallel arrays. The cells readily responded to stimulation with ACTH by releasing corticosterone, aldosterone and deoxycorticosterone. Stimulation with ACTH also induced changes in both the cell morphology and the cytoskeleton. Exposure of the cells to Krebs-Henseleit buffer containing 1–24 ACTH caused them to form numerous fine filopodia, to lose their stress fibers, and to form a thick ring of actin at the periphery of the cell. In addition, many cells became extremely arborized with many long branched dendritic processes. The morphological changes appeared to be related to a redistribution of the actin components, and may be explained only in part by the rounding up or retraction of the cytoplasm. The results strongly suggest an involvement of the actin components of the cytoskeleton in the steroidogenic response to corticotropic stimulation.
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  • 39
    ISSN: 1432-0878
    Keywords: Peripolar cell ; Glomerulus ; Kidney ; Cytoplasmic granules ; Scanning electron microscopy ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The peripolar cell is a unique cell type in the mammalian glomerulus. Peripolar cells are said to be identifiable during light microscopy by their cytoplasmic granules and by their position at the vascular pole; and during scanning electron microscopy by their distinctive surface morphology. We used both techniques to count peripolar cells in 6 normal rat kidneys. Scanning microscopy revealed that 55(±5)% of glomeruli contained at least one peripolar cell whereas light microscopy revealed granulated peripolar cells in only 4(±2)% of glomeruli. Vascular poles which contained peripolar cells previously identified by scanning were then examined by light and by transmission electron microscopy. Serial sections through these peripolar cells demonstrated the absence of cytoplasmic granules. Our observations suggest that the majority of peripolar cells in the rat contain no granules.
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  • 40
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    Microscopy Research and Technique 22 (1992), S. 160-169 
    ISSN: 1059-910X
    Keywords: Freeze-fracture and cytoplasmic maceration ; Chloroplasts ; Pollen ontogeny ; SEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The application of the freeze-fracture and cytoplasmic maceration technique in ultrastructural studies of plant cells is described. A major advantage of the technique is, that by extracting mobile cytoplasmic components from the freeze-fractured cells, surface relief is introduced and three-dimensional information is obtainable. The details of specimen preparation are described and the results obtained are reviewed. The use of chitosan embedding for very small or fragile specimens is described. © 1992 Wiley-Liss, Inc.
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    Microscopy Research and Technique 22 (1992), S. 130-150 
    ISSN: 1059-910X
    Keywords: Electron microscopy ; Scanning electron microscopy ; High resolution ; Cytoskeleton ; Biological specimen preparation ; Cultured cells ; Electrophoresis ; Bifunctional crosslinking reagents ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Today's electron microscopes have a resolution sufficient to resolve supramolecular structures. However, the methods used to prepare biological samples for electron microscopy often limit our ability to achieve the resolution that is theoretically possible. We use whole mounts of detergent-extracted cells grown on Formvar-coated gold grids as a model system to evaluate various steps in the preparation of biological samples for high resolution scanning electron microscopy (SEM)Factors that are important in determining the structure and composition of detergent-extracted cells include the nature of the detergent and the composition of the extraction vehicle. Chelation of calcium is extremely important to stabilize and preserve the cytoskeletal filaments. We have also demonstrated both morphologically and by gel electrophoresis that treatment of cells with bifunctional protein crosslinkers before or during extraction with detergent can significantly enhance the preservation of both proteins and supramolecular structures.The methods used to dry samples are a major determinant of the quality of structural preservation. For cytoskeletons freeze-drying (FD) is superior to critical point-drying (CPD), one reason being that CPD samples have to be dehydrated, thereby causing more shrinkage as compared to FD samples. The high pressures to which samples are exposed during CPD may also cause increased shrinkage, and water contamination during CPD causes severe structural damage. We have obtained the best structural preservation of detergent-extracted and fixed cells by manually plunging them into liquid propane and drying over night in a freeze-drayer.The factor that most limits achievement of high resolution in SEM is the metal coat, which has to be very thin, uniform, and free of grain in order not to hide structures or to create artifactual ones. We have found that sputter-coating with 1-3 nm of tungsten (W) or niobium )Nb( gives extremely fine-grained films as well as satisfactory emission of secondary electrons. These samples can also be examined at high resolution by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The best preservation and visualization of supramolecular structures have been obtained using cryosputtering, in which the samples are freeze-dried and then sputter-coated within the freeze-dryer while still frozen. © 1992 Wiley-Liss, Inc.
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  • 42
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    Microscopy Research and Technique 20 (1992), S. 50-72 
    ISSN: 1059-910X
    Keywords: Vimentin ; Cytokeratin ; Testis ; Cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Using immunohistochemical techniques both at light and electron microscopic levels, the arrangement and distribution of intermediate filaments in Sertoli cells of normal testis (in rat and human), during pre- and postnatal development (in rabbit, rat, and mouse) and under experimental and pathological conditions (human, rat), have been studied and related to the pertinent literature. Intermediate filaments are centered around the nucleus, where they apparently terminate in the nuclear envelope providing a perinuclear stable core area. From this area they radiate to the plasma membranes; apically often a close association with microtubules is seen. Basally, direct contacts of the filaments with focal adhesions occur, while the relationship to the different junctions of Sertoli cells is only incompletely elucidated. In the rat (not in human) a group of filaments is closely associated with the ectoplasmic specializations surrounding the head of elongating spermatids. Both in rat and human, changes in cell shape during the spermatogenic cycle are associated with a redistribution of intermediate filaments. As inferred from in vitro studies reported in the literature, these changes are at least partly hormone-dependent (vimentin phosphorylation subsequent to FSH stimulation) and influenced by local factors (basal lamina, germ cells). Intermediate filaments, therefore, are suggested to be involved in the hormone-dependent mechanical integration of exogenous and endogenous cell shaping forces. They permit a cycledependent compartmentation of the Sertoli cell into a perinuclear stable zone and a peripheral trafficking zone with fluctuating shape. The latter is important with respect to the germ cell-supporting surface of the cell which seems to limit the spermatogenetic potential of the male gonad.
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  • 43
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    Microscopy Research and Technique 20 (1992), S. 232-250 
    ISSN: 1059-910X
    Keywords: Spermiogenesis ; Spermatozoa ; Mammals ; Cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Identification of the cytoskeletal elements and their role in the formation as well as the maintenance of head membrane compartmentalization is a much debated issue in mammalian spermatozoa. Data which have emerged during the last ten years are summarized. Those which have converged in a common opinion, such as the distribution of actin in mammalian spermiogenesis, are distinguished from those which have to be confirmed, such as the role of actin related proteins and actin in mature spermatozoa.
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  • 44
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    Microscopy Research and Technique 20 (1992), S. 288-297 
    ISSN: 1059-910X
    Keywords: SEM ; TEM ; Guinea pig ; Cochlea ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Inner ear tissue of the normal guinea pig was conductively stained (OTOTO-method) for SEM investigations. The Hensen's cells of the organ of Corti were removed using a micromanipulator inside the SEM. By this method atypical bodies of sensory and supporting cells were revealed in the apical turns of the cochlea. Atypical sensory cells showed great variations in size and shape. Several had no contact to Deiter's cells and no or only one nerve supply at their basal end. Atypical Deiter's cells showed alterations in shape and in the form of their phalangeal processes.Additionally altered parts of the organ of Corti were isolated by micromanipulation and embedded for correlative TEM-investigations.
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  • 45
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    Microscopy Research and Technique 23 (1992), S. 142-156 
    ISSN: 1059-910X
    Keywords: Cytoskeleton ; Ultrastructure ; Microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The olfactory neuron is specialized along its length into highly determined morphological regions. These regions include the dendritic cilia, dendritic vesicle, dendritic shaft proper, perikaryon, axon, zone of transition where the axon widens as it approaches its termination, and the axon terminal. Except for the zone of transition and the terminal, characteristic populations of microtubules occur in these compartments. In the olfactory vesicle, three discrete microtubule organizing centers (MTOCs) nucleate microtubules: the basal body, the lateral foot associated with the body, and dense masses of nearby material. Little is known about MTOCs elsewhere in the neuron, although the polarity of the axonal microtubules indicate that they originate at or near the perikaryon. An attempt is made to summarize what is known of the origin, structure, distribution, and function of microtubules in vertebrate olfactory neurons, which are useful model systems in which to study microtubules. Information about olfactory neuron microtubules may be applicable to neurons in general (e.g., the discovery that axons contain microtubules of uniform polarity was first made in the olfactory neuron) or to microtubules in other eukaryotic cells. © 1992 Wiley-Liss, Inc.
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  • 46
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    Microscopy Research and Technique 23 (1992), S. 225-229 
    ISSN: 1059-910X
    Keywords: Scanning electron microscopy ; Ultrastructure ; Zona pellucida ; Mucus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The fine structure of the zona pellucida (ZP) covering the oocyte and of the mucus covering the surface of the intestinal villi was investigated by using a new method employing ruthenium red (RR), saponin, and osmium-thiocarbohydrazide impregnation.The glycoproteic matrices both appeared constituted by thin filaments (ranging from 22 to 50 nm in thickness) anastomosed to form a very fine network.RR prevented the dissolution and/or alteration of glycoproteins and polyanionic carbohydrates induced by acqueous fixatives. Saponin was a detergent of the soluble proteins. Osmium-thiocarbohydrazide preserved the glycoproteic matrix filaments from the mechanical stress induced by dehydration and critical point drying and reduced filaments packing and shrinkage. The technical improvement was demonstrated by the following results: 1) a regular arrangement of the filaments network; 2) a thickness of mucus filaments smaller than that obtained with other methods of preparation; 3) a homogeneous thickness of ZP filaments.This method allowed a very detailed study of the fine structural organization of the ZP and intestinal mucus. Therefore, this technique can be useful for a better evaluation of the morphodynamic of these and other glycoproteic matrices. © 1992 Wiley-Liss, Inc.
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  • 47
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    Microscopy Research and Technique 20 (1992), S. 219-231 
    ISSN: 1059-910X
    Keywords: Sertoli cell ; Nucleus ; Cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Sertoli cell nuclei are characterized by deep invaginations and, in addition, the orientation of the nuclei with respect to the wall of the seminiferous tubules varies during the cycle of the seminiferous epithelium. These events may be the result of cytoplasmic filaments acting at the level of the nuclear capsule and may represent significant changes in Sertoli cell activity. Thus, a study was performed to characterize the nature of the perinuclear filaments of Sertoli cells in vivo and in vitro.In Sertoli cells in vivo, microtubules and microfilaments were often detected in the perinuclear cytoplasm, and these cytoskeletal components were observed to course either parallel to, or abut at, the nuclear capsule. In Sertoli cells in vitro, the nuclear infoldings are retained and the perinuclear cytoskeleton was shown to contain microtubules, f-actin, and intermediate filaments. A fixation-permeabilization protocol employing tannic acid-saponin was used and it significantly enhanced the preservation of cytoskeletal components. The presence of f-actin was demonstrated by using the S1 fragment of muscle myosin to decorate the microfilaments. Treatment of the cultured cells with either microtubule or f-actin depolymerizing agents had no effect on nuclear shape. Thus, at present, the function of the prominent perinuclear cytoskeletal components remains unknown.
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  • 48
    ISSN: 1432-0878
    Keywords: Mesenteric artery ; Muscle, smooth ; Scanning electron microscopy ; Elastic fibers ; Collagen ; Extracellular matrix, structures ; Rat (Wistar Kyoto, WKY)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat mesenteric arteries, perfusion fixed in relaxed or contracted conditions, were digested with acid and elastase, bleach (sodium hypochlorite), or alkali to selectively remove collagen, elastin, or cells. Scanning electron microscopy was used to study the three-dimensional organization of the remaining cells or extracellular components. Smooth muscle cells of the tunica media were elongated and circumferentially oriented. Superior mesenteric artery cells had an irregular surface with numerous projections and some ends were forked. Small mesenteric artery cells were spindle shaped with longitudinal surface ridges, and showed extensive corrugations upon contraction. Elastin was present both as laminae and as an interconnected fibrous meshwork. Collagen was arranged in an irregular network of individual fibrils and small bundles of fibrils that formed nests around the cells in both arteries. This irregular arrangement persisted, with no apparent reordering or loss of order, upon contraction. The lack of an ordered arrangement or specialized organization at the cell ends suggests mechanical coupling of the cells to elastin or collagen throughout the length of the cell, allowing for force transmission in a number of directions. The tunica media is thus a “composite” material consisting of cells, elastin, and collagen. The isotropic network of fibers is well suited for transmitting the shearing forces placed on it by contraction of smooth muscle cells and by pressure-induced loading.
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  • 49
    ISSN: 1432-0878
    Keywords: Mucus ; Holocrine secretion ; Intermediate filaments ; Keratins ; Cytoskeleton ; Hagfish (Eptatretus stouti) ; Cyclostomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The hagfishes (cyclostomes) are known to secrete copious amounts of mucus mainly by the holocrine mode from the slime glands. Stressed animals release two types of cells (gland thread cells, GTCs; gland mucous cells, GMCs) which rupture on contact with water and rapidly form a mass of viscous mucus. Herein we report some key sequential events of this process and document a novel role for cytoskeletal polymers. After electrostimulation of Pacific hagfish (Eptatretus stouti), the exudate was collected in a stabilization buffer and GTCs segregated from GMC vesicles. Water was added progressively to mixtures of known quantities of these entities. The changing mucous composition and properties were monitored by light- and electron microscopy, viscometry and immunogold assay. Sequentially, the threads uncoil from GTCs, aggregate with the vesicles, the vesicles rupture and release mucin-like substances, at least some of which adhere to the thread. It was found that the intermediate filament (IF)-rich threads markedly facilitate hydration and modulate the viscoelastic and cohesive properties of the resultant mucus. It was speculated that the thread abets localization of mucus in an aqueous environment and promotes adhesion of mucus to surfaces such as the fish integument. As judged by immunostaining in situ, GTCs, as well as several cell-types in the epidermis, contain keratin-like components. The role of biopolymers on the properties of teleost and mammalian mucus is discussed.
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  • 50
    ISSN: 1432-0878
    Keywords: Rhabdomeres ; Cytoskeleton ; Actin ; Immunocytochemistry ; Membrane shedding ; Leptotarsus spp. (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rhabdomeres of tipulid flies lose membrane during turnover from a ‘shedding zone’ composed of microvillar tips. These distal domains lack intramicrovillar cytoskeletons and appear to be empty sacs of membrane. Recent concerns about the role of ninaC mechano-enzymes in the architecture of dipteran rhabodomeral microvilli and the dynamic role that they may play in the creation of shedding zones demand an examination of the distribution of actin in tipulid rhabdomeres. We compared rhabdomeres from tipulid retinae incubated before fixation for immunocytochemistry in a buffer without additives and a stabilising buffer that contained a cocktail of cysteine protease inhibitors; both were challenged by an anti-actin antibody for immunogold labelling after embedding in LR White Resin. Shedding zones thus processed collapse to structureless detritus. Stabilised and unstabilised shedding zones were immunonegative to anti-actin. To ensure that the negative results were not consequent upon conformational changes generated by the processing protocol, we examined microvilli of degenerating rhabdomeres of the Drosophila light-dependent retinal degeneration mutant rdgB KS222 (which separate and collapse without creating a shedding zone) and found the detritus they generate to be immunopositive to anti-actin. Stabilised and unstabilised regions of basal regions of tipulid rhabdomeres were equally immunopositive. We infer that (a) actin is absent from shedding zones; (b) actin is not degraded by microvillar cysteine proteases. The implications of these conclusions are discussed in relation to some functional models of arthropod photoreceptor microvilli.
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  • 51
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    Cell & tissue research 266 (1991), S. 385-389 
    ISSN: 1432-0878
    Keywords: Amniotic epithelium ; Cytoskeleton ; Filaments ; α-Actinin ; Ezrin ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The amniotic epithelium constitutes a diffusion barrier controlling the passage of solutes and water between the aminotic cavity and maternal circulation. With the present immunocytochemical approach, we have shown that several major components of the cytoskeleton, i.e., actin, α-actinin, spectrin and ezrin, are preferentially associated with the apical and lateral cell surfaces of the human amniotic epithelium. Keratins are distributed throughout the entire cytoplasm, whereas vimentin mainly forms a perinuclear scaffold. These findings indicate a role of the various components of the cytoskeleton in the structural integrity and modulation of cell shape and junctional permeability.
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  • 52
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    Cell & tissue research 266 (1991), S. 525-534 
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Microtubules ; Microfilaments ; Spermatogonia ; Testis ; Ephestia kuehniella (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Testis follicles of Lepidoptera contain a large somatic cell termed Verson's cell. The present study focuses on the structure of Verson's cells and neighbouring germ cells in the Mediterranean mealmoth, Ephestia kuehniella (Pyralidae), using electron microscopy, antitubulin immunofluorescence, and phalloidin incubation for the visualization of microfilaments. Verson's cells of young larvae are connected with the follicle boundary and show large areas containing packages of glycogen particles, whereas Verson's cells of pupae lie freely within the testis follicle and are largely devoid of glycogen. Both developmental stages of Verson's cells have in common the presence of a dense cytoplasmic network of microtubules. A juxtanuclear subset of the cytoplasmic microtubule array is recognized by an antibody against acetylated microtubules. This indicates that more stable microtubules exist in this region. Microfilaments are arranged parallel to the cytoplasmic microtubules. The microtubule-microfilament-complex forms a cytoskeleton that may keep larger organelles, such as mitochondria and lysosomes, in a juxtanuclear position. Chromatin within the nuclei of Verson's cells is largely decondensed and nuclear pores are abundant. This indicates a high synthetic activity within the cells. The development of cells directly attached to Verson's cells, viz. prespermatogonia, may be controlled by the Verson's cells. Prespermatogonia, which differ in cytoplasmic density from spermatogonia further away from Verson's cells, may represent stem cells that give rise to spermatogonia and somatic cyst cells upon detachment from Verson's cells. This suggestion is compatible with the low division rate of prespermatogonia.
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  • 53
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    Cell & tissue research 263 (1991), S. 61-69 
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Hybridization, in situ ; mRNA ; Myofibrils ; Myosin ; Slow isoform ; Myotubes ; Regeneration ; Muscle, striated, skeletal ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Myosin mRNA distribution was compared to the distribution of striations, nuclei, and cytoskeletal components in normal fibers and in fibers undergoing growth and repair processes in response to stretch. Plantarflexion of rabbit lower hindlimb for 4 or 6 days resulted in a 35% increase in weight of the tibialis anterior muscle. Slow myosin expression in stretched fibers increased such that the proportion of fibers shifted from the fast type towards an intermediate type. Semi-quantitative in situ hybridization revealed a large increase in concentration of slow myosin mRNA in stretched fibers. Polysomes translating myosin heavy chain were excluded from the intact myofibrillar lattice. Significant increases of myosin mRNA concentration occurred only in the outer 8 μm subsarcolemmal annulus of these stretched fibers (P〈0.001) where myofibril formation also was evident. In some fibers, stretch caused myofibrillar disorder where nuclei became centrally located, and focal concentrations of myosin mRNA also occurred. We discuss mechanisms for mRNA accumulation and favor free diffusion to loosely packed cytoplasmic regions where myosin is needed for myofibrillar growth and repair.
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  • 54
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    Cell & tissue research 263 (1991), S. 399-403 
    ISSN: 1432-0878
    Keywords: Compound eyes ; Cytoskeleton ; Actin filaments ; Cytochemistry ; Phalloidin ; Calliphora erythrocephala (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Filaments that probably consist of actin have been observed by electron microscopy in various cells and structures of the compound eye of insects and crustaceans. The overall distribution of F-actin in the compound eye of Calliphora erythrocephala was studied using fluorescent phalloidins as specific probes for F-actin. F-actin is localized (1) in the rhabdomeres, (2) in the Semper cells, (3) in the basement membrane, and (4) associated with desmosomes and membranes. It is concluded that the actin filaments present in the compound eye are involved in mechanical stabilization (e.g., within microvillar processes of the Semper cells and in association with intercellular contacts) and in motile phenomena (e.g., in the rhabdomeric microvilli).
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  • 55
    ISSN: 1432-0878
    Keywords: Heart ; Cytoskeleton ; Freeze-etching ; Desmin ; Immuno-gold staining ; S1-decoration ; Chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The three-dimensional organization of cytoskeletal filaments associated with the myofibrils and sarcolemma of the myocardial cells of early chick embryos was studied by the rapid-freeze deep-etch method combined with immunocytochemistry. In the endoplasmic region of saponin-treated myocardial cells, 12–14 nm filaments formed a loose network surrounding nascent myofibrils. These 12–14 nm filaments attached to the myofibrils and some of them converged into Z disc regions. In the non-junctional cytocortical region thinner 8–11 nm filaments composed a dense network just beneath the sarcolemma. In myofibril terminating regions at the sarcolemma, i.e., the fascia adherens, 3–5 nm cross-bridges were observed among the thin filaments. In Triton-permeabilized and myosin subfragment 1 (S1)-treated samples, subsarcolemmal 8–11 nm filaments proved to be S1-decorated actin filaments under which there was a loose network of S1-undecorated filaments. Subsarcolemmal S1-decorated actin filaments had mixed polarity and attached to the sarcolemma at one end. A loose network of S1-undecorated filaments among myofibrils in the endoplasmic region was revealed to consist of desmin-containing intermediate filaments after immuno-gold staining for desmin. These networks connecting myofibrils with sarcolemma were assumed to play an important role in integrating and transmitting the contractile force of individual myofibrils within early embryonic myocardial cells.
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  • 56
    ISSN: 1432-0878
    Keywords: Proventriculus ; Endocrine secretory cells ; Secretory granules ; Peptide hormones ; Colocalization ; Immunocytochemistry ; Colloidal gold ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The endocrine cells of the chicken proventriculus were investigated immunocytochemically, using the peroxidase-antiperoxidase technique on paraffin and semithin sections for light microscopy, and immunogold staining in osmium-fixed material for electron microscopy. The fixation procedure also allowed a detailed ultrastructural investigation. Twenty-three antisera were tested and 7 immunoreactive cell-types were identified: D-cells containing somatostatin-like peptide; EG-cells immunoreactive to anti-glucagon, anti-GLP1 and antineurotensin; NT-cells labelled only with anti-neurotensin; BN-cells containing bombesin-like material; ENK-cells showing met-enkephalin immunoreactivity; EC-cells reactive to anti-serotonin; and APP-cells positive to anti-avian pancreatic polypeptide. In addition, enterochromaffin-like (ECL) cells, were also detected by electron microscopy. The presence of ENK-cells and the ultrastructure of these and NT-cells are described for the first time in chicken proventriculus, and glucagon, GLP1 and neurotensin are shown to be colocalized in the EG-cells.
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  • 57
    ISSN: 1432-0878
    Keywords: Neurosecretosomes ; Pituitary ; Microvesicles ; Vacuoles ; Endocytosis ; Colloidal gold ; Rat (Long Evans, Brattleboro)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The hypothesis that the retrieval of membranes of neurohypophysial neurosecretory granules (NSG) and small electron-lucent microvesicles occurs by different routes was tested by incubating neurohypophysial neurosecretosomes with colloidal gold particles of various sizes. Neurosecretosomes derived from normal Long Evans rats and incubated in media of normal ionic composition endocytosed a few small (〈25 nm) gold particles into 40–50 nm electron-lucent microvesicles. After depolarisation, more small gold particles were found in microvesicles, and small and large (〉25 nm) gold particles in vacuoles. Oxytocin-containing neurosecretosomes derived from Brattleboro rats, which contain 160 nm-diameter NSG, endocytosed gold particles in a pattern indistinguishable from that of neurosecretosomes from Long Evans rats. However, neurosecretosomes derived from defective vasopressin neurones of Brattleboro rats, which contain microvesicles, small vacuoles, and a few 100 nm dense-cored vesicles, but not 160 nm NSG, endocytosed only small colloidal gold particles. Early after depolarisation the gold particles were present only in microvesicles, but later some could be found in vacuoles and lysosome-like structures. Immunogold cytochemistry using a polyclonal antiserum raised against microvesicle-rich neurosecretosomes derived from Brattleboro rats labelled microvesicles in the posterior pituitary strongly, NSG weakly, and vacuoles to a variable extent. These data together indicate that, after exocytosis, the membranes of NSG are recaptured as large vacuoles. Microvesicles are exocytosed and endocytosed separately.
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  • 58
    ISSN: 1432-0878
    Keywords: Islets of Langerhans ; Microangioarchitecture ; Corrosion casts ; Scanning electron microscopy ; Naja naja, Vipera russelli, Echis carinatus (Serpentes)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Due to a decided lack in the literature of reports on the microangioarchitecture of the pancreas of snakes, an analysis was performed in three different species of two different ophidian families with the use of cast preparations and complementary scanning electron microscopy. The vascular architecture reflects the lobular substructure of the pancreas; the organ is supplied by branches of the superior mesentric artery. Coiled lobular arteries and arterioles continue into a meshwork of capillaries. Dilated capillaries of the endocrine portion of the pancreas are an integral component of this fine capillary network. A few very small capillaries establish a connection between the endocrine and the exocrine pancreas. The other capillaries drain into venules, which ultimately join their respective veins. No interspecific differences were noted in the vascularization of the pancreas of the three ophidian species examined. The present results suggest the existence of arterio-venous anastomoses and speak against the presence of a portal system, but establish a feed-forward capillary connection from the endocrine to the exocrine component of the ophidian pancreas.
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  • 59
    ISSN: 1432-0878
    Keywords: Myofibrils ; Cytoskeleton ; Extracellular matrix ; Laminin ; Collage ; Actin filaments ; Vinculin-Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neonatal rat cardiomyocytes were cultured on extracellular matrix components laminin and collagens I+III to examine effects of extracellular matrix on the assembly of cytoskeletal proteins during myofibrillogenesis. Myofibril assembly was visualized by immunofluorescence of marker proteins for myofibrils (f-actin for I bands and α-actinin for Z bands), focal adhesions (vinculin), and transmembrane extracellular matrix receptors (β1 integrin) as cells spread for various times in culture. By 4 h in culture, f-actin appeared organized into nonstriated stress-fiber-like structures while α-actinin, vinculin and β1 integrin were localized in small streaks and beads. Subsequently, striated patterns were observed sequentially in the intracellular cytoskeletal components α-actinin, vinculin, f-actin, and then in the transmembrane β1 integrin receptor. These data support an earlier model for sarcomerogenesis in which stress-fiber-like structures serve as initial scaffolds upon which α-actinin and then vinculin-containing costameres are assembled. This sequential and temporal assembly was the same on both laminin and collagens I+III. A quantitative difference, however, was apparent on the 2 matrices. There was an increased appearance on collagens I+III of rosettes (also called podosomes or cortical actin-containing bodies in other cells) which consisted of an f-actin core surrounded by α-actinin, vinculin and β1 integrin rims. The increased incidence of rosettes in neonatal myocytes on collagens I+III suggests that these cytoskeletal complexes are involved in recognition and interaction with extracellular matrix components.
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  • 60
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    Cell & tissue research 266 (1991), S. 219-221 
    ISSN: 1432-0878
    Keywords: Uterine tube (oviduct) ; Isthmic myosalpinx ; Smooth muscle cells ; Embryo transport ; Scanning electron microscopy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The three-dimensional architecture of the human isthmic myosalpinx is directly visualized by means of scanning electron microscopy after removal of interstitial connective tissue through NaOH maceration and ultrasound microdissection. These investigations show that the myosalpinx is composed of irregularly running bundles of smooth muscle cells, changing their orientation within the myosalpinx and displaying longitudinal, oblique and circular directions. The muscular bundles anastomose and intermingle with other bundles running at different levels in the oviduct wall, and actually give rise to a wide and complex muscular network in which no distinct layers are readily discernible. These morphological data are consistent with the physiological findings that the transport of gametes and embryo in very early stages in the isthmic portion of the oviduct tube is the result of a discontinuous pattern of forward and backward movements.
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  • 61
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Ear, middle ; Contractile apparatus ; Hair cells ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lateral membrane system of the cochlear outer hair cell, consisting of the lateral plasma membrane, pillars, filamentous lattice and subsurface cisternae, is considered to be involved in the contractile movement of the isolated cochlear outer hair cell. The filamentous lattice, called the cytoskeletal spring, has been identified in the demembranated cochlear outer hair cell treated with the detergent Triton X-100. In this study, the quick-freeze, deep-etch method was applied to demonstrate the three-dimensional organization of both the filamentous and membranous structures of the lateral membrane system of cochlear outer hair cells. Treatment with saponin revealed that the inner leaflet of the lateral plasma membrane of the cochlear outer hair cell possesses more membrane particles than the outer leaflets, and that the pillars are closely associated with membrane particles in the inner leaflet of the lateral membrane. The presence of filamentous bridges between the filamentous lattice and the subsurface cisternae was also detected. We propose that the lateral membrane system in the cochlear outer hair cell may play an important role in the tuning mechanisms within the cochlea in normal hearing.
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  • 62
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    Cell & tissue research 264 (1991), S. 269-281 
    ISSN: 1432-0878
    Keywords: Interstitial tissue ; Kidney ; Scanning electron microscopy ; Vasa recta ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cytoarchitecture of the interstitial tissue of the rat kidney was studied by combined scanning and transmission electron microscopy. The renal interstitium is composed of an elaborate network of stellate sustentacular cells. In the cortex, sustentacular cells radiate thin branching processes to form a fine reticulum, which supports intertubular spaces. In the medulla, these cells extend thick processes horizontally along the basal surfaces of the thin limbs or vasa recta, reinforcing their attenuate walls. The horizontal processes connect with each other at their terminals, compartmentalizing the interstitial space into thin layers. The medullary sustentacular cells contain abundant small lipid droplets. The network of sustentacular cells houses vasa recta, keeping them in parallel position to each other and to the tubules. The arterial vasa recta are accompanied by pericytes, which frequently contain lipid droplets larger in size than those in the sustentacular cells. Venous vasa recta extend numerous basal microvilli, which anchor the venous wall to adjacent tubules or vessels. Numerous free cells, round in shape, are found in the sustentacular cell network, especially in the cortex. They consist of macrophages and occasional lymphocytes. Some macrophages extend long pseudopodia, while others make intimate contact with lymphocytes, suggesting their high level of activity.
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  • 63
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Scanning electron microscopy ; Lectin-gold particles ; Cytology ; Glycoproteins ; Imaginal discs ; Tissue culture ; Plodia interpunctella (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Indian meal-moth cell line, IAL-PID2, established from larval wing discs was examined from the 250th to the 300th passages. The cultured cells retain various structural and functional qualities of epidermal cells. Under hormone-free conditions PID2 cells grow as a monolayer of round or spindle-shaped cells. They appear as weakly active epidermal cells. The endoplasmic reticulum and Golgi apparatus are poorly developed and secretory activity is reduced. Culture conditions resulted in considerable cellular expansions, abundance of storage products (glycogen, lipids), and hypertrophy of the lysosomal system. The PID2 cell line retains the ability to respond to ecdysteroids; 20-hydroxyecdysone treatment (2×10-6 M) triggered morphogenetic and secretory processes. Cells formed pseudoepithelial aggregates interconnected and linked by desmosome-like structures. The hormone-stimulated cells are involved in the biosynthesis of N-acetyl-D-glucosamine-rich glycoproteins. The glycosylation sites were located, by use of WGA-gold particles, on cellular expansions and all along the plasma membrane. The possible significance of these glycoproteins is discussed.
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  • 64
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    Journal of Electron Microscopy Technique 17 (1991), S. 81-94 
    ISSN: 0741-0581
    Keywords: Colloidal gold ; Pathogenesis-related (PR) proteins ; Tobacco plants ; Hypersensitivity ; Tobacco mosaic virus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Immunocytochemical techniques are confronted with the problem of obtaining adequate tissue preservation together with retention of protein antigenicity. Various methods, including freeze-drying and freeze-substitution, have been devised to circumvent this problem. In the present study, we report that microwave energy used in combination with low concentrations of glutaraldehyde (0.1%) and paraformaldehyde (2%) preserves the structural integrity of plant tissue and antigenicity of proteins. Tobacco leaf samples fixed in a time as brief as 15-20 s exhibited excellent preservation of fine structures. By contrast, specimens irradiated for shorter (5-10 s) or longer (30-40 s) periods showed poor morphological preservation. Microwave irradiation for 15-20 s was found useful for immobilizing large amounts of soluble antigens. The fast microwave fixation method was successfully used to preserve pathogenesis-related (PR) proteins, which were subsequently localized by a postembedding immunogold procedure. In addition to soluble antigens, cellulose subunits and pectic substances, two major plant cell wall components, were found to be highly preserved in microwave-irradiated tobacco plant tissue. The present study demonstrates that microwave fixation of plant tissue is a simple and inexpensive method that is easy to perform with commercially available microwave ovens. The incubation time for fixation is reduced from 2 h to 15-20 s without loss of fine structural details. This method will undoubtedly acquire increasing applicability and relevance in plant biology.
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  • 65
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    Journal of Electron Microscopy Technique 18 (1991), S. 126-134 
    ISSN: 0741-0581
    Keywords: Sequential extraction ; Whole-mount cell ; Monoclonal antibody ; Colloidal gold ; Cross-reaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Whole-mount, sequentially extracted cells combined with immunogold electron microscopy were developed to demonstrate the intermediate filaments, lamina, and nuclear matrix (IF-L-NM) and to identify their protein components. The IFs of HeLa cells were reacted both with keratin and vimentin monoclonal antibodies; meanwhile, the IF network of BHK-21 cell was reacted only with vimentin monoclonal antibody. The lamina and nuclear matrices of both HeLa and BHK-21 cell were labelled, respectively, with lamin monoclonal antibody-gold complex and 280 Kd nuclear matrix protein monoclonal antibody-gold complex. The monoclonal antibody to keratin could cross-react with the lamina both of HeLa and BHK-21 cells.
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  • 66
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    Journal of Electron Microscopy Technique 18 (1991), S. 197-202 
    ISSN: 0741-0581
    Keywords: Graft ; Transplant ; Labeling ; Colloidal gold ; Sendai virus ; Cortex ; Nucleus basalis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The ability to discriminate between host and donor cells is required to interpret the organization of neural grafts at the electron microscopic (EM) level. Using light microscopy, Ardizzoni et al. (Ardizzoni, S.C., Michaels A., and Arendash, G.W. [1988] Science 239: 635-637) described a method, using gold-filled Sendai viral envelopes, for labeling cell suspensions prior to grafting. As the colloidal gold used in this procedure is especially attractive for use with EM, we have examined the ultrastructural distribution and character of this label with transplanted cells. Cell suspensions taken from the nucleus basalis of fetal rats were labeled using gold-filled Sendai viral envelopes and grafted into the dorsal neocortex of adult host rats with nucleus basalis lesions. After varying survival times ranging from 1 to 14 months, grafts and surrounding host tissue were examined using standard EM techniques. Within the graft site, gold particles ranging from 10-200 nm were found associated with various membranes throughout the cytoplasm of both neurons and glia. Gold particles of similar size were also found within the nuclei of neuronal and non-neuronal cells. Host cells near the graft site contained some small gold particles (10-40 nm). Control injections of non-viable, gold-labeled cells or colloidal gold alone resulted in similar patterns of small gold particles which were readily discriminable from the larger virally inserted gold particles found in viable labeled donor cells. We conclude that this method allows discrimination between closely associated host and donor cells.
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  • 67
    ISSN: 0741-0581
    Keywords: SEM ; Intestinal morphology ; Intracellular structure ; Mitochondria ; Cell membrane ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Improvements in the design of modern scanning electron microscopes (SEM) and new methods of specimen preparation incorporating chemical removal of the cytosol and cytoskeleton, now make it possible to view cells and their organelles in three dimensions (3D) at high magnification. In this experiment, high resolution SEM (HRSEM) utilizing new methods of tissue preparation was used to study the intracellular structures of the mouse ileum. In addition, in vivo intestinal perfusion was used to further enhance cellular preservation. Using these modifications it was possible to visualize, in 3D, the fine structure of intestinal epithelial cells and intracellular organelles such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi complex, as well as microvilli and cell membrane. Whole mitochondria appeared as irregularly shaped organelles which contained tubular cristae. Plate-like cristae were not observed. The brush border was found to be a closely packed array of cylindrical projections. The extensive folding and structural intricacy of lateral cell membranes between absorptive cells could only be appreciated by viewing this tissue with 3D HRSEM. The use of HRSEM to study 3D ultrastructure of cells and their organelles will improve our understanding of the structure-function relationships in both the healthy and diseased gastrointestinal tract.
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  • 68
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    Journal of Electron Microscopy Technique 19 (1991), S. 316-326 
    ISSN: 0741-0581
    Keywords: Quick-freeze deep-etching ; Endothelium ; Cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A three-dimensional study of the ultrastructure of endothelial cells is helpful in understanding important endothelial functions such as vascular transport and cell permeability. For this purpose, in addition to serial sectioning electron microscopy and high-voltage electron microscopy, the quick-freeze, deep-etching technique also enables us to analyze structures at the molecular level by its high resolution and is useful for three-dimensional morphological studies.Some modifications on the conventional deep-etching method were made in this study to reduce the undesirable aggregation of proteins and salts during etching. Using this technique, we examined the rat aortic endothelium, particularly the membrane structures and cytoskeletons.The luminal surface of the endothelium was covered with a fine filamentous coat, which was anchored to the plasma membrane. In the cytoplasm, actin filaments were prominent and were oriented randomly or in a parallel fashion near the plasma membrane. Of the vesicles seen in the endothelium, some had basket coats of clathrin, and others had striped coats on the cytoplasmic membrane surface. These surface structures of the vesicles suggest the transport mechanism of the vesicles in association with the fine filaments attached to the vesicles.
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  • 69
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    Journal of Electron Microscopy Technique 18 (1991), S. 106-116 
    ISSN: 0741-0581
    Keywords: Cell monolayers ; Scanning electron microscopy ; Cell morphology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The ultrastructural characteristics of several growth matrices were examined using two cell types chosen for their distinct growth habits. Chinese hamster ovary cells and Balb-c 3T3 mouse fibroblasts were grown on flat substrates (glass, tissue culture plastic, Millipore filters) as well as spherical (glass, tissue culture plastic, cross-linked dextran) substrates. Cells were plated maintaining equal densities and growth surface area. Once the majority of the cells reached confluency, the cell's morphology on each matrix was examined using scanning electron microscopy. Digital analysis was performed on cell attachment area to compare the effect of each matrix on cell spreading.Variation in cell shape was dramatic between matrices, being most noticeable between a textured surface (filter, dextran bead) and that of a smooth (glass) surface. Even within smooth surfaces, some variation was observed. There was also an effect of matrix curvature on cell attachment area, the greatest being in the 3T3-c Balb cells, causing an overall decrease in the area of attachment between cell and matrix. The changes seen could also be related to the particular cell type used. Hamster ovary cells tended to be cylindrical and showed little effect between matrices, whereas the mouse fibroblasts, which are more flattened, showed the matrix effect to a greater degree.This study demonstrates the necessity of being aware of substrate-induced cell changes in tissue culture, where some variation in cell shape may be due to the surface on which the cells are grown as opposed to the experimental procedure.
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  • 70
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    Journal of Electron Microscopy Technique 18 (1991), S. 121-125 
    ISSN: 0741-0581
    Keywords: Immunocytochemistry ; Colloidal gold ; Cerium chloride ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Immunoelectron microscopic localization of surface antigens on lymphocytes is possible using alkaline phosphatase combined with cerium-based cytochemical methods. Distinctive electron-dense deposits are easily identified at sites of antibody binding. Mouse splenocytes showing surface immunoglobulin localization and human peripheral blood lymphocytes stained for the MHC-Class II antigen HLA-DR illustrate the results. Double staining for murine Ia antigen by the alkaline phosphatase procedure, combined with immunogold labeling of antigens identified on dendritic cells, i.e., NLDC-145, demonstrates the utility of the cerium cytochemical method.
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  • 71
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    Journal of Electron Microscopy Technique 19 (1991), S. 486-490 
    ISSN: 0741-0581
    Keywords: Alveoli ; SEM ; Stereo pair images ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Alkali digestion has been used to remove cellular elements of tissues thus exposing the underlying connective tissue framework. We studied the action of this severe alkali treatment on the delicate tissues of rat lung. The lungs of male Sprague-Dawley rats were perfused with saline to remove blood and then inflated by fixation through the airways at 20 cm pressure. Sections of lung 2 × 5 × 5 mm were immersed in 2.5 M NaOH at 25°C for 6 h, 16 h, 24 h, 48 h, and 72 h. The alkali was changed daily. Tissues were washed to neutral with water (24 h), treated with tannic acid (1%, 3h), post-fixed with osmic acid (1%, 3 h) and processed for SEM. At 6 h, epithelial cells started to peel off the alveolar surface. At 16 h the digestion process was well advanced. At 48 h the cells were completely removed revealing the lattice network of connective tissue fibers within the alveolar surface. The method allows the complete removal of cellular elements of the lung while retaining the very fine 3D structure of the connective tissue matrix.
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  • 72
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    Journal of Electron Microscopy Technique 18 (1991), S. 50-60 
    ISSN: 0741-0581
    Keywords: Confocal microscopy ; Light microscopy ; Scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have adapted a tandem scanning confocal microscope for real-time, non-invasive imaging of cells under in vivo conditions. This form of in vivo confocal imaging relies on the optical sectioning abilities of the confocal microscope to obtain en face, sequential, reflected light images of cells at various depths, up to 1 mm, within opaque organs in living animals. Of major consideration in the design of an in vivo confocal microscope is maximizing the real-time detection of signals reflected from low contrast structures which can be affected by the microscope design, objective, and image detector systems. Using an in vivo confocal microscope design with a 20 × BioOptics surface contact objective we have obtained live cellular images from selected tissues including cornea, kidney, liver, adrenal, thyroid, epididymis, and muscle and connective tissue of rabbits and rats. Images were captured, digitized, and processed using a DAGE Mti low light level SIT camera coupled to a Gould IP9527 image processor. In vivo images were also compared with conventional bright field light and scanning electron microscopic images of “dead,” fixed tissues. Overall, in vivo confocal imaging can provide remarkable detail of living cells comparable to that of conventional microscopic images of “dead,” fixed, and stained tissue. A more unique feature of in vivo confocal imaging is the ability to study cellular structure and function sequentially over time in the same organ or tissue and represents a fundamentally new paradigm in microscopy. With continued refinements in the microscope, objective and detection system designs and their consequent improvements in lateral and axial resolution, in vivo confocal microscopy will enable us as observers to see what no one has been able to see before.
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  • 73
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    Journal of Electron Microscopy Technique 19 (1991), S. 419-428 
    ISSN: 0741-0581
    Keywords: Hand skin ; Resin cast ; Capillary loops ; Scanning electron microscopy ; Changes with age ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The microvasculature of the skin of the hand in primates, including man, was examined by means of scanning electron microscopy of corrosion casts. In this study, the microvascular patterns and structures in different areas of the hand, and the changes in vascular patterns that occur with age, have been described.The typical structure of the capillary loops in the hand can be observed in the ball of the finger of the young adult monkey. The capillary loops were formed out of not just one capillary vessel, but two or three vessels. Each capillary vessel arose and divided into several branches at the papillae, and these became descending limbs. After the loop passed a hairpin turn, the descending limbs were 1.5 times larger than the ascending limbs in the intrapapillary portion, and they became extrapapillary venules. The descending limbs connected with the postcapillary venules in the postpapillary portion and with the horizontal network. The postcapillary venules fused with each other to form the primary and secondary venous arcades. The secondary venous arcades anastomosed with each other and flowed into the subpapillary venules, which run along the dermal furrow in the fingerprint.Changes in vascular patterns with age could be observed. In the infant fingerprint, the vascular systems had not yet differentiated, especially the venous system in the dermis. In the old adult finger, the capillary loops presented complicated features deviating due to aging.
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  • 74
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    Journal of Electron Microscopy Technique 19 (1991), S. 189-202 
    ISSN: 0741-0581
    Keywords: Rat testis ; Irradiation ; Scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Newly developed techniques in high-resolution scanning electron microscopy (SEM) and for tissue-processing procedures have been applied to an investigation of structures of various cells in rat testes at different stages of gonadal maturation. A series of high-resolution SEM micrographs are presented which survey the surfaces of different types of testis cells during normal development, and which also illustrate ultrastructural features of some of their intracellular organelles. In addition, a series of high-resolution SEM micrographs are presented which compare the structural features of Sertoli cells in normal testes with those in germ-cell-depleted testes obtained from rats killed at varying times after having been irradiated in utero. We describe our observations on the structural properties of surfaces and intracellular organelles in Sertoli cells, Leydig cells, peritubular myoid cells, and some classes of germinal cells. We also consider the possible role of Sertoli cell apical cytoplasmic processes in lumen formation. Similarities are pointed out between the structure of germ-cell-depleted testes, resulting from irradiation in utero, and the structure of germ-cell-depleted testes in seasonal breeders during periods of involution. Finally, we discuss advantages and disadvantages of methods employed to reveal the fine structure of intracellular organelles in cells of the testis.
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  • 75
    ISSN: 1432-0878
    Keywords: Collagen fibrils ; Sciatic nerve ; Epineurium ; Perineurium ; Endoneurium ; Scanning electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The organization of collagen fibrils in the rat sciatic nerve was studied by scanning electron microscopy after digestion of cellular elements by sodium hydroxide treatment, and by conventional transmission electron microscopy. The epineurium consisted mainly of thick bundles of collagen fibrils measuring about 10–20 μm in width; they were wavy and ran slightly obliquely to the nerve axis. Between these collagen bundles, a very coarse meshwork of randomly oriented collagen fibrils was present. In the perineurium, collagen fibrils occupied the interspaces between the concentrically arranged perineurial cells; in each interspace, they formed a sheet of characteristic lacework elaborately interwoven by thin (about 3 μm or less in width) bundles of collagen fibrils. In the subperineurial region, there was a distinct sheet of densely woven collagen fibrils between the perineurium and underlying endoneurial fibroblasts. In the endoneurium, collagen fibrils surrounded individual nerve fibers in two layers as scaffolds: the inner layer was made up of a delicate meshwork of very fine collagen fibrils, and the outer one consisted of longitudinally oriented bundles of about 1–3 μm in width. The collagen fibril arrangement described above may protect the nerve fibers against external forces.
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  • 76
    ISSN: 1432-0878
    Keywords: Foot pad ; Microvasculature ; Eccrine glands ; Scanning electron microscopy ; Vascular corrosion replicas ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The entire microvascular architecture in rat foot-pads including that of eccrine sweat glands was studied by scanning electron microscopy using a vascular corrosion-cast replication technique. In the central roofs of the pads, particularly elaborate capillary networks were arranged in rows perpendicular to the long axis of the foot. In the marginal regions of the pads, simple networks of capillaries were arranged in lamellar sheets parallel to the surface of the sole of the foot. Complex spongy networks of vascular trees were observed in the subcutaneous layer of the pads. These vessels were supplied by the pad artery, and then, after forming capillary networks in the roofs of the pads, they drained into the metatarsal vein. Rod-shaped cages of capillaries were observed around the eccrine sweat glands. One descending arteriole, arising from a connecting arteriole, and a few venules were connected with these capillary cages at their upper and lateral sides. Occasional arterio-venous and veno-venous anastomoses were also observed around the eccrine sweat glands. This microvascular architecture may adjust well to the mechanical and physiological conditions encountered in the foot-pads. The relation of the microvascular architecture around the eccrine sweat glands with their development is also discussed.
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  • 77
    ISSN: 1432-0878
    Keywords: Neuronal surface ; Perikaryal projections ; Dorsal root ganglia ; Enzymatic digestion ; Scanning electron microscopy ; Rabbit (New Zealand White)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The true surface of rabbit spinal ganglion neurons has been made directly accessible to scanning electronmicroscope observation after removal of both the connective tissue and satellite cells that normally cover it. The neuronal surface is characterized by a profusion of slender projections whose shapes have been determined and whose length and width have been quantified. Controls carried out with transmission electron microscopy demonstrate that the procedure employed in this study satisfactorily preserves neuronal structure.
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    Cell & tissue research 261 (1990), S. 35-47 
    ISSN: 1432-0878
    Keywords: Microvessel endothelial cells ; Cell culture ; Corpus luteum ; Scanning electron microscopy ; Cow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological heterogeneity has not been documented for cultured endothelial cells isolated from the microvascular bed of any organ. As the corpus luteum depends on a rich microvascularization, endothelial cells were dislodged from developing corpora lutea by mechanical dissection followed either by collagenase digestion or by no digestion. Cell separation was carried out by Percoll density centrifugation. Although the yield of intact cells was higher with collagenase treatment than without, successful endothelial cell cultures were only established when cells remained untreated. Viewed by light microscopy after an average lag phase of 10 days, five different phenotypes of endothelial cells were found under similar simple culture conditions: isomorphic epithelioid, polymorphic epithelioid, spindle-shaped, round, and phase-dense phenotypes. Monolayers appeared within 2–4 weeks. After an additional period of 2–4 weeks, tubular forms with a specific pattern were noted for types 1–3, the so-called pseudotubular forms for type 4, and none for type 5. Cell types differed in their cytochemical and immunocytochemical responses. Examined by SEM, type 1 displayed a more conspicuous surface anatomy than type 2. Types 3–5 demonstrated striking cell processes that were characteristic of each type. Tubular forms of types 1 and 2 showed cell borders and a marked increase in surface specializations, whereas tubular forms of type 3 lacked detectable cell borders in the absence of a striking surface anatomy. Pseudotubular forms of type 4 developed no particular spatial organization. Thus, for the first time, morphological evidence is provided that different endothelial cell types are obtained from diverse segments of the microvascular bed.
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  • 79
    ISSN: 1432-0878
    Keywords: Organelle transport ; Cytoskeleton ; Colcemid ; Cytochalasin ; Spongilla lacustris (Porifera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Different antibodies against actin, tubulin and cytokeratin were utilized to demonstrate the spatial organization of the cytoskeleton in basal epithelial cells of the freshwater sponge Spongilla lacustris. Accordingly, actin is localized in a cortical layer beneath the plasma membrane and in distinct fibers within the cytoplasmic matrix. Microtubules exhibit a different distributional pattern by radiating from a perinuclear sheath and terminating at, the cell periphery; in contrast, intermediate filaments are lacking. Cytoplasmic streaming activity was studied by in-vivo staining of mitochondria and endoplasmic reticulum by means of fluorescent dyes. Single-frame analysis of such specimens revealed a regular shuttle movement of mitochondria and other small particles between the cell nucleus and the plasma membrane, which can be stopped in a reversible manner with the use of colcemid or colchicine but not with cytochalasin D. The results point to the microtubular system as a candidate for cell organelle transport, whereas the actomyosin system rather serves for changes in cellular shape and motility.
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    Cell & tissue research 260 (1990), S. 431-434 
    ISSN: 1432-0878
    Keywords: Actin ; Cytoskeleton ; Immunocytochemistry ; Photoreceptor cells ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Drosophila ninaC mutation produces small rhabdomeres with the axial filament of the microvillar cytoskeleton reduced or missing. Using post-embedding immunogold labelling of LR White-embedded eyes, we show that several alleles of this mutation retain positive anti-actin immunoreactivity in the rhabdomeres, comparable to that of wild-type flies.
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  • 81
    ISSN: 1432-0878
    Keywords: Stress fibers ; Mesothelium ; Cytoskeleton ; Fluorescence cytochemistry ; Actin filaments ; Rana catesbeiana (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or α-actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery.
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    Lasers in medical science 5 (1990), S. 375-379 
    ISSN: 1435-604X
    Keywords: Scanning electron microscopy ; Photodynamic therapy (PDT) ; Haematoporphyrin derivative (HPD) ; Helium-neon laser ; Laser microirradiation ; PTK2 ; Hela ; Microvilli ; Filopodia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper reports an ultrastructural study of cell surfaces in normal (PTK2) and malignant (Hela) cells in vitro using the scanning electron microscope. The study describes cells treated by haematoporphyrin derivatives (HPDs) from different sources as well as the destruction of cells which have taken up HPD in combination with laser microirradiation of single cells. The results indicate that an HPD effect on cell surface structure occurred: in general the microvilli were markedly reduced and some of the filopodia broken, shortened and thickened. The effects of different HPD drugs on cell surface structure differed to a certain extent within the limits of normal variation. In addition ultrastructural observations following HPD treatment plus laser microirradiation showed remarkable photodynamic cell damage identifiable within seconds after treatment.
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    Journal of Electron Microscopy Technique 15 (1990), S. 104-114 
    ISSN: 0741-0581
    Keywords: Nerve fiber ; Afferent and efferent nerves ; Cochlea ; Fetal inner ear ; Human ear ; SEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The cochleas of four human fetuses ranging 22-25 weeks gestation were studied by scanning electron microscopy (SEM) for the purpose of obtaining a better understanding of the nerve fiber arrangement in the human ear. After critical point drying, the specimens were dissected and the floor of the tunnel of Corti and the outer wall of Nuel's space were exposed for observation. Upper cochlear turns, especially the apical turn, seemed to be still immature.Observed nerve fibers were classified into three types:1Spiral fibers: Fibers traveling basalward and following the shape of the cochlea were found in both the tunnel of Corti and Nuel's space and believed to be the afferent nerves responsible for innervating the outer hair cells2Radial fibers: radiating outward from the osseous spiral lamina - one such radial fiber transversing high in the tunnel space (supposedly the efferent nerve servicing the outer hair cells), and another sort of radial fiber (found crossing the tunnel floor), the nature of which was uncertain.3Irregular fibers: Consisting of thin, randomly running fibers within the cochlea. The destination of these fibers was not determined, but possibly they represent transitory nerve branchings of afferent or more probably efferent nerves, which would later regress during maturation.
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    Journal of Electron Microscopy Technique 15 (1990), S. 155-164 
    ISSN: 0741-0581
    Keywords: Spiral ganglion ; Freeze-fracture ; Intermediate filaments ; Morphology ; Cytoskeleton ; Membrane ; Labyrinth ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Freeze-fracture analysis of adult spiral ganglion cells of CBA/CBA mice revealed two types of membrane specializations. Most cells (type I) had a smooth surface and were surrounded by Schwann cells. Type II spiral ganglion cells showed numerous membrane specializations with well-delineated indentations similar to those previously found on hair cells adjacent to afferent and efferent nerve endings. Immunomorphological analysis (using well-defined monoclonal antibodies directed against different subclasses of intermediate filament proteins) revealed a unique co-expression of neurofilaments, vimentin and cytokeratins in spiral ganglion cells of 8-to 22-week human fetuses.
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  • 85
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    Journal of Electron Microscopy Technique 15 (1990), S. 245-260 
    ISSN: 0741-0581
    Keywords: Stereocilia ; Postmortem cochlea ; Scanning electron microscopy ; Human ; Guinea pig ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The morphology of hair bundles has been studied by high resolution scanning electron microscopy using a variety of fixatives, including glutaraldehyde, glutaraldehyde-picrate, glutaraldehyde-tannic acid, glutaraldehyde followed by post-fixation in osmium tetroxide, and the osmium thiocarbohydrazide technique. Critical evaluation of several metal coatings, gold, gold-palladium, and platinum has been carried out.Both the surface texture of stereocilia and their cross-links are sensitive to fixation and metal coating. We are of the opinion that glutaraldehyde gives the best general quality of fixation and preservation for all types of cross-links. We have described three major sets of cross-links: first, lateral links connecting stereocilia within the same row; second, lateral links connecting stereocilia of adjacent rows; and third, upward-pointing links, one per stereocilium, connecting the tip of each shorter stereocilium to the lateral surface of the adjacent taller stereocilium. Current physiological and anatomical evidence suggests that the lateral links couple the individual stereocilia within the hair bundle so that they function as a single mechanical unit. The upward-pointing tip links are ideally placed to respond to mechanical deformation of the hair bundle, being stretched when the stereocilia are deflected in the excitatory direction towards the tallest row and relaxed when deflected in the opposite, inhibitory direction.Postmortem morphological changes are detected within 15 minutes of cardiac arrest and become progressively more pronounced in time. These results enabled us to distinguish specific druginduced changes which could not be attributed simply to cell death. Effects of cisplatin and kanamycin upon hair bundles are described. The work reported here is based on studies using the guinea pig cochlea. Some of the postmortem changes described have also been confirmed in human cochleas.It is stressed that many of the postmortem and drug-induced effects can only reliably be studied by high resolution scanning electron microscopy coupled with appropriate prearation procedures.
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  • 86
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    Journal of Electron Microscopy Technique 14 (1990), S. 1-5 
    ISSN: 0741-0581
    Keywords: Scanning electron microscopy ; Microanalysis ; Elemental mapping ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A technique was developed to prepare archaeological fiber cross sections for electron microscopic examination and x-ray analysis. Use of this new method allows chemical and morphological information to be obtained from the interior of a single fiber or yarn. Fibers are fractured while frozen and then freeze dried. Following mounting and carbon coating, fibers are examined by scanning and backscatter electron microscopy and then analyzed by using energydispersive spectrometry. Elemental distribution is mapped by using image-processing software. In this report, the described technique is employed in the examination of ancient fibers from three different long-term storage environments (moist buried, dry buried, museum stored). Data obtained by examining the interior of fibers such as these provide insight into the conditions of a fiber's growth, the treatments applied during the fiber's processing and use, and the conditions in which the fiber was stored.
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  • 87
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    Journal of Electron Microscopy Technique 14 (1990), S. 367-372 
    ISSN: 0741-0581
    Keywords: Scanning electron microscopy ; Basement membranes ; Colonic development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have used two epithelial-stripping techniques in our studies of the basal lamina in the developing rat colon. The first involves prolonged osmication followed by sonication; the second uses chelation of calcium by EDTA followed by sonication. Both techniques remove the epithelium from the basal lamina; however, the EDTA/sonication technique appears to produce a cleaner adepithelial surface of the basal lamina. In addition, the fine structure of the basal lamina appears to be better preserved in specimens prepared by the EDTA/sonication technique. In contrast, the basal lamina of specimens prepared by the osmium/sonication technique has a shattered appearance that we believe is due to an increase in the fragility of the delicate fetal basal lamina.
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  • 88
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    Journal of Electron Microscopy Technique 14 (1990), S. 298-306 
    ISSN: 0741-0581
    Keywords: Colloidal gold ; Critical point drying ; Hairy cell leukemia ; Interleukin-2 receptor ; Macrophages ; Lymphokine-activated killer cells ; Peldri II ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: For many years critical point drying (CPD) has been the method of choice for preparing cells for scanning electron microscopy (SEM). Described herein is a simple, efficient, inexpensive, reproducible, and safe procedure using Peldri II, a proprietary fluorocarbon compound that is solid at room temperature and a liquid above 25°C, as a sublimation dehydrant for processing specimens for SEM. The utility of Peldri II was demonstrated in studies using leukocytes from the blood of healthy donors and patients with leukemia as well as from long-term lymphoblastoid cell lines. The application of the proposed Peldri II procedure was further documented in SEM studies in which the expression and distribution of the interleukin-2 receptor (IL-2R) on leukocyte surface membranes was imaged using colloidal gold-labeled antibodies (i.e., immunogold). When compared with current SEM preparation procedures using CPD, Peldri II is a useful alternative that is thought to offer several important advantages.
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    Journal of Electron Microscopy Technique 15 (1990), S. 261-279 
    ISSN: 0741-0581
    Keywords: Cochlea ; Hair cell ; Cytoskeleton ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The organization of microtubules in hair cells of the guinea-pig cochlea has been investigated using transmission electron microscopy and correlated with the location of tubulin-associated immunofluorescence in surface preparations of the organ of Corti. Results from both techniques reveal consistent distributions of microtubules in inner and outer hair cells.In the inner hair cells, microtubules are most concentrated in the apex. Reconstruction from serial sections shows three main groups: firstly, in channels through the cuticular plate and in a discontinuous belt around its upper perimeter; secondly, forming a ring inside a rim extending down from the lower perimeter of the plate; and thirdly, in a meshwork underlying the main body of the plate. In the cell body, microtubules line the inner face of the subsurface cistern and extend longitudinally through a tubulo-vesicular track between the apex and base.In outer hair cells, the pattern of microtubules associated with the cuticular plate is similar, although there are fewer present than in inner hair cells. In outer hair cells from the apex of the cochlea, microtubules occur around an infracuticular protrusion of cuticular plate material. In the cell body, many more microtubules occur in the region below the nucleus compared with inner hair cells.The possible functions of microtubules in hair cells are discussed by comparison with those found in other systems. These include morphogenesis and maintenance of cell shape; intracellular transport, e.g., of neurotransmitter vesicles; providing a possible substrate for motility; mechanical support of structures associated with sensory transduction.
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  • 90
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    Cell & tissue research 258 (1989), S. 617-629 
    ISSN: 1432-0878
    Keywords: Axonal transport ; Cytoskeleton ; Node of Ranvier ; Schmidt-Lanterman incisure ; Synaptic vesicle ; Torpedo marmorata (Elasmobranchii) ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Binding sites for antibodies against membrane proteins of synaptic vesicles have been shown to be enhanced at nodes of Ranvier in electromotor axons of the electric ray Torpedo marmorata and sciatic nerve axons of the rat, using indirect immunofluorescence and monoclonal antibodies against the synaptic vesicle transmembrane proteins SV2 and synaptophysin (rat) or SV2 (Torpedo). In the electric lobe of Torpedo, vesicle-membrane constituents occurred at higher density in the proximal axon segments covered by oligodendroglia cells than in the distal axon segments where myelin is formed by Schwann cells. Antibody binding sites were enhanced at nodes forming the borderline of the central and peripheral nervous systems. Filamentous actin was present in the Schwann-cell processes covering both the nodal and the paranodal axon segments as suggested by the pattern of phalloidin labelling. Furthermore, in rat sciatic nerve, Schmidt-Lanterman incisures were intensely labelled by phalloidin. A similar nodal distribution was found for binding sites of antibodies against actin and myosin. Binding of antibodies to tubulin was enhanced at nodes in Torpedo electromotor axons. The apparent nodal accumulation of constituents of synaptic vesicle membranes and the presence of filamentous actin and of myosin are discussed in relation to the substantial constriction of the axoplasm at nodes of Ranvier.
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    Cell & tissue research 258 (1989), S. 425-428 
    ISSN: 1432-0878
    Keywords: Arteriovenous anastomoses ; Vascular innervation ; Tongue ; Transmission electron microscopy ; Scanning electron microscopy ; Dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Profiles of nerve plexuses in the arteriovenous anastomoses of the dog tongue were investigated by both transmission and scanning electron microscopy. Three-dimensional morphology of the vascular nerves was examined after removal of the connective tissue components by the HCl-hydrolysis method. Tight bending and a rich nerve supply were the most characteristic features of the anastomosing channels. The tunica media consisted of an outer circular layer of typical smooth-muscle cells and an inner region containing longitudinal plicae of ramified smoothmuscle cells. The tunica adventitia was exclusively occupied by nerve bundles; fibroblasts were poorly developed. Numerous nerve bundles of variable size were coiled around the anastomosing channels, and occasional bundles ran crosswise over the U-shaped bent vessels.
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  • 92
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    Cell & tissue research 258 (1989), S. 373-380 
    ISSN: 1432-0878
    Keywords: Stress fibers ; Mesothelium ; Fluorescent cytochemistry ; Actin filaments ; Cytoskeleton ; Rana catesbeiana (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Actin-containing cytoplasmic fibers in mesothelial cells of the abdominal wall of the bullfrog, Rana catesbeiana, were visualized by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers ran straight and were aligned parallel with each other. They also showed immunofluorescence staining with antibody against myosin or α-actinin. Electron microscopy revealed the presence of microfilament bundles in the basal cytoplasm of the cells. These cytoplasmic fibers may be comparable to the stress fibers observed in cultured cells. The mesothelial cells of tadpoles initially developed stress fibers when they underwent transformation from a polygonal to a spindle-like shape. Such fibers were also present in the polygonal cells of frogs. Expression of stress fibers in these cells seems to correspond to the expansion of the abdominal wall caused by marked growth of some intraperitoneal organs. The stress fibers in the mesothelial cells may serve to regulate cellular transformation and, further, may play a role in maintaining cellular or epithelial integrity by strengthening the cellular attachment to subepithelial tissue against probable tension load on the abdominal wall.
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  • 93
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    Cell & tissue research 256 (1989), S. 495-505 
    ISSN: 1432-0878
    Keywords: Retina ; Cytoskeleton ; Development, ontogenetic ; Immunofluorescence microscopy ; Man ; Mouse C57 BL/6J
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to define cytoskeletal domains of the mammalian photoreceptor, actin and tubulin were localized in adult retinae of mouse and human. For light-microscopic localization, actin was labeled using fluorescent phalloidin or monoclonal antibodies against actin, and tubulin was labeled using monoclonal antibodies against alpha- and beta-tubulin in an immunocytochemical method. Actin and tubulin were also localized by ultrastructural immunocytochemistry in the mouse. Filamentous actin was present in the retina at the outer limiting membrane and in synaptic terminals, especially of the cones, while globular actin was observed additionally in the inner segments. Müller cell cytoplasm and apical microvilli at the outer limiting membrane were also labeled for filamentous actin. Alpha- and beta-tubulin were evident throughout the photoreceptors, including the inner segments, but not in the synaptic terminals or at the outer limiting membrane. In the early postnatal retina of mouse, actin and tubulin were present at the ventricular surface. This pattern changed as photoreceptors fully elongated and as synaptogenesis occurred in the outer plexiform layer.
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    Cell & tissue research 256 (1989), S. 283-292 
    ISSN: 1432-0878
    Keywords: Dorsal root ganglion ; Chromatolysis ; Cytoskeleton ; Cryofixation ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cytoskeletal alterations in the cytoplasm of chromatolytic neurons of the dorsal root ganglia were studied in chickens after transection of the sciatic nerves. These studies were carried out using cryofixation with a nitrogencooled propane jet. By this method, the morphological complexity of the cytoskeleton in normal perikarya and cell processes can be visualized. The cytoskeleton of the dorsal root ganglion cells (DRG) is composed of an intricate network of microtubules, neurofilaments and microfilaments. The membrane-bounded cell organelles, as well as the cell nucleus and the plasmalemma, are linked to the microtubules and neurofilaments by microfilaments (or crosslinkers). As a result of the transection of the axon, chromatolysis takes place, characterized by dislocation of cell organelles, ↭ eccentric position of the nucleus and dispersion of the parallel cisternae of the rough endoplasmic reticulum throughout the cytoplasm. This characteristic phenomenon coincides with a regression of the neurocytoskeletal network. The neurofilaments and microtubules become shorter, and the microfilaments are replaced by strands of globular or granular material. The temporary regression of the microfilaments leads to a dispersion of the cell organelles. During the remodelling of the cytoskeletal structures, proliferation of the neurofilaments in the regenerating neurons may occasionally be observed. These results show that the cytoskeletal structures are responsible not only for the preservation of cell shape, but also for the maintenance of the normal distributional pattern (location and mobility) of the intracellular components.
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    Cell & tissue research 257 (1989), S. 201-206 
    ISSN: 1432-0878
    Keywords: Peripolar cell ; Efferent arteriole ; Afferent arteriole ; Kidney ; Scanning electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The interior of Bowman's capsules of rat kidneys has been examined by scanning electron microscopy, and a distinctive population of cells around the exposed vascular poles of glomerular tufts were identified. The cells were situated in the annular groove at the root of the glomerulus, between the parietal epithelial cells and the podocytes. These peripolar cells were dendritic cells with long processes embracing the glomerular arterioles. Up to three peripolar cells were present at each vascular pole and they were mainly distributed in the glomeruli of the outer third of the renal cortex. This first detailed study of the surface morphology of the glomerular peripolar cell supports the suggestion that changes in the diameter of the polar region of the glomerular tuft may cause variations in stretching of the cuff of peripolar cells, and hence modulation of their secretory activity.
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  • 96
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    Keywords: Tissue culture ; Aorta ; Muscle, smooth ; Dibutyryl cAMP ; Cytochalasin B ; Cytoskeleton ; Rat (Wistar-Kyoto) ; Rat SHR (spontaneously hypertensive)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study analyzed effects of dibutyryl cyclic AMP (DB-cAMP) and cytochalasin B (CB) on the morphology of cultured aortic smooth muscle cells (SMC) from rat using phase-contrast microscopy, scanning electron microscopy, and fluorescence staining of actin filaments by the NBD-phallacidin method. The exposure of SMC to each of these agents led to rapid, extensive, and reversible (within 1–2 h of drug withdrawal) changes in their morphology including cytoplasmic arborization (stellation). The latter was preceded by (i) marginal membrane ruffles (DBcAMP) and (ii) increased zeiotic activity (CB), which were visible within 20 min of the exposure, followed (30–90 min incubation) by a centripetal retraction of the cytoplasm and progressive development of complete or partial arborization. Further, the effects of substances interfering with the assembly-disassembly of microtubules (colchicine, taxol, lidocaine) on DB-cAMPand CB-induced arborization were studied. None of these agents antagonized CB-induced morphological changes. Colchicine, but not lumicolchicine, taxol, or lidocaine (in a short-term study) prevented DBcAMP-induced arborization. Taxol added to cell cultures for 24 h promoted DB-cAMP-induced arborization. Both DB-cAMP and CB resulted in the disintegration of actin filaments. The present data suggest that the arborization of cultured aortic SMC is a cytoskeleton-based process involving stabilization of microtubules and disintegration of actin filaments. Our study also suggests that the SMC arborization may represent an in vitro case of SMC stellation found in situ.
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  • 97
    ISSN: 1432-0878
    Keywords: SEM ; TEM ; Interstitial cell ; Myenteric plexus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An extensive cellular network becomes visible over the myenteric plexus of the rat after removal of the overlying tissues under the scanning electron microscope. The cells are mainly stellate and have many slender processes via which they interconnect. They form a three-dimensional network and are closely associated with the ganglia and nerve bundles, and also extend over the smooth muscle cells. They are considered to correspond to the interstitial cells of Cajal because of their peculiar arrangement and their topography. Transmission electron-microscopic evidence demonstrates that the majority of those cells have features of fibroblasts. Gap junctions and intermediate junctions are observed between these fibroblast-like cells, and also between them and smooth muscle cells. Examination of serial thin sections reveals that single fibroblast-like interstitial cells connect to both circular and longitudinal muscle cells via gap junctions. It is suggested that the network of interstitial cells conducts electrical signals.
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  • 98
    ISSN: 1432-0878
    Keywords: Muscle, striated, skeletal ; Slow muscle fibers ; Muscle cells ; Sarcoplasmic reticulum ; Scanning electron microscopy ; Rana n. nigromaculata (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The three-dimensional structure of the sarcoplasmic reticulum (SR) in the slow (tonic) fibers of the reclus abdominis muscle of the Japanese meadow frog (Rana nigromaculata nigromaculata Hallowell) was examined by high resolution scanning electron microscopy, after removal of the cytoplasmic matrices by the osmium-DMSO-osmium procedure. The SR forms a repetitive network throughout these fibers. At the level of the Z-line, a slender transverse tubule (T-tubule) runs transversely to the longitudinal axis of the myofibril. Small, spherical or ovoid terminal cisternae couple laterally with the T-tubule at intervals of 0.4–1.0 μm, and form a “terminal cisterna-T-tubule complex” on whose surface tiny indentations are occasionally seen. Each terminal cisterna gives rise to a few sarcotubules that run in various directions, divide frequently and form circular or oval meshes of diverse sizes in front of the A- and I-bands. The sarcotubules usually form small meshes in the middle of the A-band, but occasionally fuse and form a poorly developed H-band (fenestrated) collar.
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  • 99
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    Cell & tissue research 256 (1989), S. 1-6 
    ISSN: 1432-0878
    Keywords: Corrosion casts ; Tracheal system ; Respiration ; Scanning electron microscopy ; Insecta ; Cataglyphis bicolor, Apis mellifera, Musca domestica (Insecta) Tracheal system, insects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tracheal systems of five insect species (two species of ants, worker bee, housefly and the cabbage butterfly) have been studied by scanning electron microscopy of corrosion casts. This technique, which is commonly used for the investigation of vertebrate vasculature, is adapted to demonstrate the ultrastructure of the insect respiratory organ. The problem of filling a “blind ending system” was solved by injecting the resin Mercox into the evacuated tracheae through a thoracal spiracle. After polymerization of the resin, the tissue was digested enzymatically and chemically. The three-dimensional structure of the tracheal system was investigated by scanning electron microscopy. The technique used here displays for the first time the complex morphology of the entire tracheal system in fine detail, especially the structure of spiracles, airsacs, tracheae and tracheoles. Smooth-walled terminal tracheoles show up in flight muscles. The finest tracheoles that could be identified have diameters of approximately 70 nm. This approaches the finest tracheoles portrayed by transmission electron micrographs.
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    Journal of Electron Microscopy Technique 12 (1989), S. 160-171 
    ISSN: 0741-0581
    Keywords: Quick-freeze deep-etch method ; Cytoskeleton ; Cryosection ; Immunoelectron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Cytoskeletons underneath the postsynaptic membrane of neuromuscular junctions were studied by using a quick-freeze deep-etched method and immunoelectron microscopy of ultrathin frozen sections. In a quick-freeze deep-etched replica of fresh, unfixed muscles, 8.9 ± 1.5-nm particles were present on the true postsynaptic membrane surface. Underneath this receptor-rich postsynaptic membrane, networks of fine filaments were observed. These cytoskeletal networks were more clearly observed in extracted samples. In these samples, diameters of the filaments which formed networks were measured. In the platinum replica, three kinds of filament were recognized - 12 nm, 9 nm, and 7 nm in diameter. The 12-nm filament seemed to correspond to the intermediate filament. The other two filaments formed meshworks between intermediate filaments and plasma membrane. In ultrathin frozen sections vinculin label was localized just beneath the plasma membrane. Thirty-six percent of the label was within 18 nm from the cytoplasmic side of the plasma membrane and 50% was within 30 nm. Taking the size of the vinculin molecule into account, it was concluded that vinculin is localized just beneath the plasma membrane and might play some role in anchoring filaments which formed meshworks underneath the plasma membrane.
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