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  • 1
    ISSN: 1432-2307
    Keywords: Mast cell ; Quick-freezing ; Compound 48/80 ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract X-ray microanalysis was performed on rat mast cells prepared by quick-freezing, cryosectioning and freeze-drying (QF-FD) method, or quick-freezing and freeze-substitution (QF-FS) method. Peritoneal cells including mast cells were stimulated with compound 48/80 for 0, 10 or 30 s at 17° C, and the mast cells stimulated for 30 s started exocytosis. In X-ray spectra of the QF-FD specimen, mast cells stimulated for 10 s increased their levels of phosphorus, sodium and chlorine in the intergranular cytoplasm prior to exocytosis, and kept this increase until 30 s after stimulation. In the QF-FS specimen, where soluble elements were removed, peaks of phosphorus, sulphur and potassium could be detected as elements in X-ray spectra. Phosphorus increased and potassium decreased in intergranular cytoplasm of mast cells stimulated for 10 s, and these changes became more obvious after 30 s. However, supplemental increase of other cations such as sodium could not be detected in the QF-FS specimens.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2307
    Keywords: Quick-freezing ; Glomerulus ; Basement membrane ; Freeze-substitution ; Deep-etching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological studies using immersion or perfusion fixation methods do not reveal the ultrastructure of functioning kidneys with normal circulation. A simple apparatus was developed for freezing the kidneys in vivo without stopping the blood supply, and the ultrastructure of the glomerular capillary loops was examined under different haemodynamic conditions. Mouse kidneys were frozen under normal blood flow conditions; others were frozen in the same way after ligation of the abdominal aorta at a point caudal to the renal arteries. They were then processed for the freeze-substitution or deep-etching method. Good ultrastructural preservation was obtained within about 5 μm depth from the frozen tissue surface. Functioning glomeruli with normal blood flow possessed open capillary lumens, different shapes of foot processes and atypical basement membranes with low density. Moreover, heterogeneity in width between foot processes was identified on the replica membranes. Under the acute conditions used to increase blood supply into the kidneys, the spaces between the flat foot processes became more widely dilated and the basement membrane was seen to be three-layered. The ultrastructure of glomeruli in functioning kidneys has been demonstrated for the first time by this “in vivo cryotechnique”.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2307
    Keywords: Mast cell ; Compound 48/80 ; Exocytosis ; Freeze-fracture immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes of intracellular localization of serotonin in rat mast cells were examined by freeze-fracture immunocytochemistry, to prevent the translocation of the serotonin antigen. Rat peritoneal cells including mast cells were stimulated in vitro with compound 48/80, at 17° C for 0, 30 or 60 s for exocytosis to occur. The mast cells were fixed, quickly frozen and freeze-fractured to expose the antigen on the fractured surface. They were immunostained with serotonin antibody, and the immunoreactions on the fractured surface were examined on ultrathin sections by electron microscopy. Unstimulated mast cells exhibited serotonin localization mostly in each intragranular matrix. In contrast, mast cells stimulated for 30 s exhibited increased serotonin in their intergranular cytoplasm. Mast cells showed more distinct immunoreactions in the cytoplasm where degranulation would be promoted after 60 s. It is suggested that intracellular release of serotonin occurred in the stimulated mast cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2307
    Keywords: Mast cell ; Compound 48/80 ; Ultrastructure ; Quick-freezing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of mast cells stimulated with compound 48/80 was examined by quick-freezing and deep-etching (QF-DE) or freeze-substitution (QF-FS) methods. Peritoneal cells including mast cells of adult male rats were stimulated in vitro with compound 48/80 at 17° C for 0, 10, 30, 60 or 180 s. The QF-DE replicas revealed that the mast cells stimulated with compound 48/80 for 30 s decreased filamentous actin around secretory granules. In the QF-FS specimens, perigranular membranes in mast cells stimulated for 60 s formed pentalaminar structures between adjacent granules in their cytoplasm prior to degranulation. These findings suggest that preparatory states for degranulation occur in the whole cytoplasm of stimulated mast cells at early stages. Moreover, both QF-FS specimens and QF-DE replicas revealed a compact morphological appearance of discharged granules in the extra-cellular space, indicating the existence of considerable content within the granules. Skeletal structures in the granules were also demonstrated on QF-DE replicas prepared after extracting soluble elements from the cytoplasm. It is suggested that the granular contents associated with the skeletal structures are gradually detached from the discharged granules to ensure local concentration in the tissues.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A novel ”in vivo cryotechnique” with replica immunoelectron microscopy was developed for detecting caveolin localization on replica membranes prepared directly from living smooth muscle cells. After quick-freezing mouse duodenal walls by our ”in vivo cryotechnique”, the specimens were prepared for freeze-fracture and deep-etch replica membranes. Then they were treated with 5% SDS and 0.5% collagenase to keep some antigens on the replica membranes. The immunogold method could be used to clarify the localization of the caveolin antigen in relation to three-dimensional ultrastructures of living smooth muscle cells. Our new cryotechnique can provide native organization of functional molecules in living cells.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 102 (1994), S. 83-87 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Changes of mast cells stimulated with compound 48/80 were morphologically investigated at different temperatures. Peritoneal mast cells of male rats were stimulated in vitro at 4 or 17° C. At 17° C, mast cells stimulated for 10 s gave decreased fluorescent reactions for phalloidin. At 30 s stimulation, they showed typical exocytosis initiated by fusions of peripherally located secretory granules to the plasma membrane. In contrast, mast cells stimulated at 4° C exhibited neither decrease of phalloidin reactions nor typical excytosis even after 30 s. It was inferred that the fusions were mediated by cytoplasmic elements, probably the actin filaments previously suggested to prevent release of secretory granules. Furthermore, the space between the perigranular membrane and granular contents was enlarged in some mast cells stimulated at 4° C. The morphological changes suggested that equivocal events occurred also in the cytoplasm of these cells. The mast cells showed no typical exocytosis at 4° C.
    Type of Medium: Electronic Resource
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