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  • Cold  (1)
  • Dark and light cells  (1)
  • Morphogenesis  (1)
  • 1970-1974  (3)
  • 1
    ISSN: 1432-0568
    Keywords: Lysosome ; Autophagy ; Phagocytosis ; Acid phosphatase ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the “physiological” cell death was studied in distal ventral bulbar cushions of 15 chick embryo hearts on the 4th and 5th day of incubation. Microperfusion fixation was performed. The ultracytochemistry of a lysosomal hydrolytic enzyme acid phosphatase was also investigated in another 15 embryonic hearts. In the course of the cell degeneration an increase in cellulr autophagy was observed without previous cytoplasmic or nuclear changes or phagocyte ingestion. A cytoplasmic diffusion of acid phosphatase outside of lysosomes was observed. Besides the cell death with the marked participation of the lysosomal system, another kind of dying cells was found, characterized by their nuclear pycnosis and cytoplasmic condensation. Starting from the 5th day of incubation the dying and dead cells were found phagocytized by some of their neighbouring viable mesenchymal cells. A formation of ribosomal crystals was not observed. The formation and fate of cytolysomes as well as the fate of phagocytes are discussed. The presence of pre-necrotic cells with important autophagy and of necrotic cells with nuclear changes was related to the possibility of a dual cause of the cell death. In the case of pre-necrotic cells the epigenetic factors like the biomechanic action of hemodynamics were considered, while the necrotic cells seem to be programmed to death by their genome. Finally the uniformity of cell death ultrastructure in different organs and species was noticed.
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  • 2
    ISSN: 1432-0568
    Keywords: Rat ; Cold ; Pineal gland ; Synaptic vesicles ; Zinc iodide-osmium tetroxide (ZIO) reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In den synaptischen Bläschen der Nervenendigungen der Epiphyse von Ratten, welche 2 und 4 Tage einer Temperatur von −6° bis −8°C ausgesetzt worden waren, hat man eine signifikante Vermehrung des Zinkjodid-Osmiumtetroxyd (ZIO) reaktiven Materials festgestellt. Der durchschnittliche Durchmesser der ZIO-positiven synaptischen Vesiculae betrug bei den Kontrollratten 234 Å und bei den Ratten, welche 2 und 4 Tage unter der Kälte gelebt hatten, 380 Å, bzw. 379 Å. Die ZIO-Reaktion war bei den Kontrollratten in 49,3% der synaptischen Vesiculae positiv, nach zweitägiger Kälteeinwirkung waren 58,7% und nach viertägiger Kälteeinwirkung 72,1% der synaptischen Vesiculae ZIO-positiv. Auf Grund der vorliegenden Arbeit war es jedoch nicht möglich zu entscheiden, ob die Vermehrung des ZIO-reaktiven Materials mit einer gleichzeitigen Zunahme der biogenen Amine verbunden ist.
    Notes: Summary In the synaptic vesicles of pineal nerve endings of Wistar rats exposed for 2 and 4 days to a temperature of −6° to −8° C, a significant increase of the zinc iodide-osmium tetroxide (ZIO) reactive material was observed. The mean diameter of ZIO reactive synaptic vesicles of control rats was 234 Å; in rats exposed to cold for 2 and 4 days it was 380 Å, respectively 379 Å. In control rats the ZIO reaction was positive in 49,3% of the synaptic vesicles. The reactivity increased to 58,7% in rats exposed to cold for 2 days, and to 72,1% in rats exposed to cold for 4 days. However, the results of the present study do not permit to conclude if an increase of ZIO reactive material is accompanied by a simultaneuos increase of biogenic amines.
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  • 3
    ISSN: 1432-0568
    Keywords: Rat kidney ; Macula densa ; Dark and light cells ; Fixation procedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Verfasser beschreiben die Ultrastruktur der dunklen Zellen in der Macula densa der Mittelstücke der Ratten-Niere nach Perfusionsfixierung in situ. In Vergleich mit den Resultaten aus einer früheren Versuchsreihe mit Immersionsfixierung ist der prozentuale Anteil der dunklen Zellen etwa viermal geringer, während ihre Ultrastruktur im Prinzip die gleiche geblieben ist. Die Verfasser vertreten die Auffassung, daß die dunklen Macula-Zellen nicht unbedingt Präparationsartefakte sind.
    Notes: Summary The authors describe the ultrastructure of the dark cells in the macula densa of the distal convoluted tubule of the rat kidney after fixation carried out by vascular perfusion in situ. In this case the frequency of the dark cells compared with that of the light cells is about four times lower than in previous investigations using the fixation procedure by immersion, whereas the ultrastructure remains essentially unchanged. However, the authors believe that the dark cells of the macula densa are not necessarily artifacts due to the preparation of the specimens for examination in the electron microscope. At present it is not yet possible to decide if the dark and the light cells are two specific cell types of the macula densa or if they represent two different functional stages of a single cell type.
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