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  • 1
    Electronic Resource
    Electronic Resource
    Neuropathological and ultrastructural findings in two cases of subacute spongiform encephalopathy (1964)
    Springer
    Acta neuropathologica 4 (1964), S. 218-229 
    Details
    ISSN: 1432-0533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die klinischen und neuropathologischen Befunde von 2 Fällen von „Encephalopathia spongiformis subacuta” werden berichtet. Beide Fälle wurden durch Hirnbiopsie verifiziert und elektronenmikroskopisch untersucht. Die Hohlräume, welche das pathologische Bild der Hirnrinde kennzeichnen, sind von einer Membran begrenzt und werden daher vom Cytoplasma nervöser Gewebselemente abgeleitet. Der Nachweis von Übergangsformen zwischen Astrocytenfortsätzen und den Hohlräumen macht ihre Entstehung aus dem Cytoplasma vergrößerter Astrocyten wahrscheinlich. Die kleinen Blutgefäße zeigen keine pathologischen Veränderungen.
    Notes: Summary This report deals with the clinical and neuropathological findings in two cases of subacute spongiform encephalopathy. Cerebral biopsies were performed in both cases and electron microscopy studies carried out. The cavities were lined by a membrane and were assumed therefore to have originated in the cytoplasm of nervous tissue elements. The presence of transitional stages between dilated astrocytic processes and large cavities makes it probable that the cavities originated from enlarged astroglial cytoplasm. No abnormalities were found in small blood vessels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00684130
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical Activity of the Intrafusal Muscle Fibres (1956)
    [s.l.] : Nature Publishing Group
    Nature 178 (1956), S. 317-318 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Some developments in recent years have helped considerably in understanding how the muscular portion of a stretch receptor is capable of modulating the frequency of sensory discharges. Alexandrowicz3 discovered some special organs in the abdomen of the lobster (Homarus vulgaris) which were ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/178317a0
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  • 3
    Electronic Resource
    Electronic Resource
    Axons Sprout and Microtubules Increase After Local Inhibition of RNA Synthesis, and Microtubules Decrease after Inhibition of Protein Synthesis: A Morphometric Study of Rat Sural Nerves (1991)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 3 (1991), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Drugs that inhibit RNA or protein synthesis are known to affect some functional properties of axons. In this context, we studied the ultrastructural effects of actinomycin-D, an inhibitor of RNA synthesis, and cycloheximide and emetine, inhibitors of protein synthesis, in rat sural nerves. A silicone sleeve (4 mm long) loaded with drug was placed around the nerves and left for about a week. The ultrastructural alterations of axons and Schwann cells progressed over this period. After cycloheximide and emetine, the cytoplasm of Schwann cells was enlarged and the rough endoplasmic reticulum was prominent. After actinomycin-D, the Schwann cells reached the stage of lysis. Nonmedullated were more affected than myelinated axons. After cycloheximide and emetine, the axoplasmic matrix decreased substantially but reversibly. Microtubules of nonmedullated fibres decreased by about 50%. Actinomycin-D determined sprouting of axons and a rise of axonal microtubules; in nonmedullated axons, the normal inverse correlation between microtubular density and calibre gave way to a high and constant density for all axonal sizes. A few millimetres proximal and distal to the sleeve, the nerve tissue and the axonal microtubular content were close to normal, i.e. the effects of drugs were local. Present results suggest that the local turnover of amino acids in the axon is necessary to maintain the integrity of microtubule and neurofilament proteins. We propose that the Schwann cell down-regulates the axonal cytomatrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1991.tb00047.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of molar concentration of fixative upon the fine structure of oxyntic cells (1966)
    Springer
    Protoplasma 61 (1966), S. 164-180 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resting and histamine-stimulated oxyntic cells ofBufo spinulosus show-striking changes in response to (a) fixation in solutions of different tonicity, and (b) thein vivo action of approximately isotonic and very hypotonic fluids. The changes are most marked in the general shape of the cell and in the membranous elements that occupy its distal third. Comparisons with other types of cells indicate that oxyntic cells ofBufo are very permeable to water. Within the cytoplasm of the oxyntic cell the same property is exhibited by the membranous elements present in its apical third. It is thought that these elements have a predominantly tubular shape in the living cell. Transformation of these tubules into cavities or the disappearance of the tubules is induced by histamine stimulation. The area of the cell membrane increases concomitantly by the formation of plate-like processes. It is concluded that the disappearance of the tubule system with increase in cell surface, and the similar permeability properties exhibited by the tubule system and the cell membrane indicate that they may be parts of a system of mutually interconvertible membranous structures. Additional experiments performed on the Bat suggest that differences in structure of the oxyntic cell reported in the literature are often due to differences in the tonicity of the fixatives used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01247917
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  • 5
    Electronic Resource
    Electronic Resource
    A critical study of the histochemical lead method for localization of Mg-ATPase at cell boundaries (1973)
    Springer
    Journal of molecular histology 5 (1973), S. 503-518 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Synopsis The staining obtained at cell boundaries by the Wachstein-Meisel technique for ATPases in the gastric gland of the toad (Bufo spinolosus) was studied. Homogenates and sections of the tissue fixed in glutaraldehyde exhibit considerable ATP hydrolytic activity in media with and without lead ions. Attempts to establish a correlation between intensity of staining and the rate of non-enzymatic hydrolysis of ATP by lead were not successful. Good staining could be obtained in media with high ATP:Pb2+ ratios where no non-enzymatic hydrolysis could be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01012057
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  • 6
    Electronic Resource
    Electronic Resource
    Electron microscope observations on the early development of the rat (1962)
    Springer
    Cell & tissue research 56 (1962), S. 157-179 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The early development of the rat, from the mature oocyte through fertilization until the 8-cell stage, has been studied with the electron microscope. The fine structure is described and discussed, with particular reference to the following topics. The middle piece of the spermatozoon is found in every stage studied, within the ovum cytoplasm; it is not significantly altered by this situation. The nucleoli are numerous during the 1-cell stage and often present in positions that suggest their extrusion into the cytoplasm; in subsequent stages a branching structure develops around them. The dividing cell presents the mitotic apparatus with its centrioles, hollow looking fibers, chromosomes, but without centromeres; in the cytoplasm the small granules align in rows. Mitochondria are evenly distributed during the 1-cell stage and can be found in the 8-cell stage constricted as if dividing. The “multivesicular bodies” constitute an abundant population of cytoplasmic elements that may be related to the endoplasmic reticulum or the Golgi complex, neither of which is clearly recognizable. In the 8-cell stage the cytoplasm segregates into two zones, one of which contains all the “multivesicular bodies”, while the mitochondria are found in both of them; this distinction provides some basis to adscribe to the “multivesicular bodies” the properties of the so called “metachromatic particles”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325111
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  • 7
    Electronic Resource
    Electronic Resource
    Fine structure of the oxynticopeptic cell in the gastric glands of an elasmobranch species (Halaelurus chilensis)This work was supported by Catholic University Research Fund, Santiago, Chile (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 193 (1979), S. 805-821 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Gastric mucosa of an elasmobranch species was examined by electron microscope. The gastric glands contain one form of cell whose fine structure is similar to the cell that secretes both hydrochloric acid and pepsinogen of the amphibian gastric glands proper. These oxynticopeptic cells are characterized by: (a) a luminal surface with long projections of cytoplasm having dilatations in their thickness; (b) a tubulo-vesicular system in the apical cytoplasm; (c) a great number of mitochondria, some of which are of great length; (d) a well developed granular endoplasmic reticulum and a conspicuous Golgi apparatus; and (e) a large nucleus with a conspicuous nucleolus. A fourth part of the cells are binucleated. Physiological implications of some of these ultrastructural features are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091930405
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution of intermediate filaments in amphibian oxyntic cells (1981)
    Springer
    Cell & tissue research 220 (1981), S. 725-737 
    Details
    ISSN: 1432-0878
    Keywords: Oxyntic cells ; Intermediate filaments ; Immunofluorescence ; Prekeratin-like filaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intermediate filaments of toad oxyntic cells were isolated and analysed by SDS-PAGE. The major proteins of the residue were identified as actin and a 51,000 dalton polypeptide. Immunological crossreactivity between toad oxyntic cell intermediate filament components and anti-prekeratin, was shown by double immunodiffusion tests and indirect immunofluorescence. The immunofluorescent decoration of oxyntic cells and the electron microscope images are coincident in locating the intermediate filaments mainly at the cortical and perinuclear basal zones. Furthermore, the cortical zone appears especially rich in prekeratin-like material at its adluminal third. This results in a cup-like structure that encloses the cell portion occupied by the tubulovesicular system, which does not contain intermediate filaments. The translocation of membranes occurring during the secretory cycle of the oxyntic cell, has been attributed to a system of contractile proteins. The disposition of the prekeratin-like material suggests a role for intermediate filaments in the generation of movement, produced by actin and myosin interaction, by providing a fixed plane for the anchoring of actin microfilaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210457
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of the reaction between orcein and the elastic fibers of the ligamentum nuchae of the horseThis investigation was supported in part by a research grant from the National Heart Institute, of the National Institutes of Health, Public Health Service. (1952)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 113 (1952), S. 197-213 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091130206
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  • 10
    Electronic Resource
    Electronic Resource
    The early changes of parietal cell structure in the course of secretory activity in the rat (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 172 (1985), S. 291-306 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the rat parietal cell was studied, both at rest and after stimulation by refeeding or insulin administration. Experiments on fixation procedures showed that whenever the fixative contained sucrose at a concentration higher than 0.2 M, the system of cytoplasmic membranes was clearly tubular in arrangement, whereas the omission of sucrose in the fixative usually resulted in a vesicular structure. The study with the high-voltage electron microscope of thick sections prepared by conventional techniques or by impregnation with zinc iodide-osmium (ZIO) revealed that the tubules are grouped into fascicles, and that these form a feltwork that is especially thick toward the cell apex. The development of the secretory canaliculus after stimulation appears to take place by an in situ remodeling of the cytoplasmic domain occupied by the tubular system. Cells examined after short periods of stimulation (5-15 min) showed images of the tubular system and of the canalicular structure which differed both from the nonstimulated and from the fully active (30-45 min of stimulation) cell. These features include the formation of wide cisternae and of pericanalicular cytoplasmic trabeculae or laminae, whose fine structure bears close resemblance to that of the intracanalicular processes in the same cells. These images can be ordered into a hypothetical sequence which is proposed as a model to explain the transformation of the tubular system and intervening cytoplasmic matrix into secretory canaliculus.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001720404
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