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91.
Ohne Zusammenfassung 相似文献
92.
Karl Hermann Andres 《Cell and tissue research》1964,64(1):63-73
Zusammenfassung An durch Perfusion mit Glutaraldehyd fixierten Rattengehirnen wurde das Erscheinungsbild der Mikropinozytose in Elementen der Meso- und Neuroglia sowie an den Perikarya und synaptischen Endformationen der Nervenzellen elektronenmikroskopisch dargestellt.Die bei der Mikropinozytose von der Zellmembran invaginierten Caveolen und Tubuli können einfache Verzweigungen zeigen. Ihre Oberfläche und die der mikropinozytotischen Bläschen zeigen an der gegen das Zytoplasma gerichteten Membranseite einen Stachelsaum. Diese Membrandifferenzierung dürfte mit der Resorption besonderer, zum Teil makromolekularer Substanzen zusammenhängen.Im Bereich großer Synapsen, z.B. in den Moosfasertelodendren der Glomerula cerebellaria oder in der Zona glomerulosa des Bulbus olfactorius sind mikropinozytotische Invaginationen und Bläschen sehr häufig. Möglicherweise übernehmen sie von den postsynaptischen Dendriten, die dünne Zytoplasmaprotrusionen in die Invaginationen hineinsenden, Stoffe. Es wird vermutet, daß es sich hierbei um inaktivierte Transmittersubstanz handelt, die auf diesem Wege dem präsynaptischen Abschnitt wieder zugeführt wird. Die zurückresorbierten Abbauprodukte der Transmittersubstanz werden in einem präsynaptischen Golgi-Komplex resynthetisiert und in synaptischen Bläschen angereichert. Dieses morphologische Bild ergänzt die biochemische Hypothese eines Acetylcholin-Kreislaufes im Bereich von Nervenendigungen.Entsprechende mikropinozytotische Erscheinungen wurden in caudalen Abdominalganglien von Leucophaea maderae beobachtet. Es wird angenommen, daß die Mikropinozytose ein allgemein verbreiteter Resorptionsmechanismus im Zentralnervensystem ist.Herrn Prof. Dr. F. Wassermann zum 80. Geburtstag gewidmet.Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
93.
The Electroosmotic Effects Arising from the Interaction of the Selectively Anion and Selectively Cation Permeable Parts of Mosaic Membranes 总被引:1,自引:0,他引:1
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It has been previously shown, theoretically and in model system experiments, that mosaic membranes composed of anion-selective (electropositive) and cation-selective (electronegative) parts interposed between electrolytic solutions of different concentrations give rise to local electrical circuits. In this work with model systems it is shown that these currents produce electroosmosis. In systems with permselective electronegative membranes and KCl solutions, the electroosmotic water transport was 16 moles/faraday. With the permselective electronegative membrane replaced by more porous electronegative membranes, the electroosmotic effects were about twice as high. With Li salts, the water transport was considerably larger. A system with a permselective electropositive membrane of 50 cm2 effective area and an electronegative membrane of 120 cm2 gave internally generated currents up to 20 ma. In extrapolating from the results with macromodels to effects with true mosaics, i.e. microsystems, it is stressed that current depends on the linear distance over which membranes interact. In true mosaic membranes, the current pathways will be of the same order as the dimensions of individual membrane microelements; the sum of all local microcurrents will be correspondingly larger than the current in the macromodel, and the electroosmotic effects will be proportionately greater. Electroosmotic effects with true charge-mosaic membranes may be of the same order or larger than the liquid transport by normal and anomalous osmosis which might occur across the individual parts of the charge-mosaic. 相似文献
94.
Karl L. Schaupp Jr. Douglas Pinto Rodney J. Valentine 《The Western journal of medicine》1966,105(2):97-101
The treatment of gas gangrene has been revolutionized by oxygen drenching of tissues infected with Clostridia. This was used in a massive infection of the abdominal wall following a traumatic abortion attempt. The clostridial infection was controlled, but the patient almost succumbed to a secondary infection of gram-negative organisms. This responded to drainage, antibiotics and general supportive measures. In the course of treatment, the value of a team approach to complicated special problems was documented. 相似文献
95.
Summary The pictures of isolated mitochondrial membranes, as seen on the electron-microscope, depend very much on the method of specimen preparation. Subunits of linear dimensions of about 25 m, (electron transport particles) are observed in carbon-replicas of the membranes and in specimens treated with trypsin or pepsin (0.02% for 30 mins) and shadowed with platinum. A three-layered structure of the unit membrane is seen in sections of specimens fixed with osmium tetroxide or formalin followed by post-fixation with osmium tetroxide. But fixation with potassium permanganate or with formalin, followed by post-fixation with potassium permanganate reveals an electron-dense globular structural element in the unit membrane. An electron-transparent ultrastructural element of the unit membrane is observed after treatment with trypsin (0.2% for 5 mins) and fixation with osmium tetroxide. Unsectioned specimens treated with 0.02% trypsin for 30 mins show a honeycomb-like structure of the membrane. Thus, part of the results appear to support the concept of a mosaic-like structure of the unit membrane, whereas other results are in agreement with the classical concept of a three-layered structure.The authors wish to express their gratitude to Dr. Sina Rosenthal, Department of Physiological Chemistry, Humboldt University, Berlin, who prepared the isolated membranes, to Mr. E. Fischer, Head Technician of the Department of Electron Microscopy, Greifswald University, who took most of the electron micrographs, to Mr. G. Bartsch, Department of Electron Microscopy, Greifswald University, and especially to Prof. W. Bargmann and to Doz. E. Lindner, Department of Anatomy, Kiel University, for many valuable suggestions. 相似文献
96.
STUDIES ON SHELL FORMATION : IX. An Electron Microscope Study of Crystal Layer Formation in the Oyster 总被引:3,自引:2,他引:1
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Details of crystal growth in the calcitostracum of Crassostrea virginica have been studied with the purpose of analyzing the formation of the overlapping rows of oriented tabular crystals characteristic of this part of the shell. Crystal elongation, orientation, and dendritic growth suggest the presence of strong concentration gradients in a thin layer of solution in which crystallization occurs. Formation of the overlapping rows can be explained by three processes observed in the shell: a two-dimensional tree-like dendritic growth in which one set of crystal branchings creeps over an adjacent set of branchings; three-dimensional dendritic growth; and growth by dislocation of crystal surfaces. Multilayers of crystals may thus be formed at one time. This is favored by infrequent secretion of a covering organic matrix which would inhibit crystal growth. The transitional zone covering the outer part of the calcitostracum and the inner part of the prismatic region is generally characterized by aggregates of small crystals with definite orientation. Growth in this zone appears to take place in a relatively homogeneous state of solution without strong concentration gradients. Thin membranes and bands of organic matrix were commonly observed in the transitional zone bordering the prismatic region. The membrane showed a very fine oriented network pattern. 相似文献
97.
Karl F. Meyer 《Microbiological reviews》1961,25(3):249-261
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