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  • 1980-1984  (4)
  • 1970-1974  (3)
  • 1
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Various methods of fixation ofDermatophagoides pteronyssinus for the REM were tested. OsO4 vapor yielded the best results. The morphology of male and female mites is described, based on REM exposures.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 161 (1980), S. 9-18 
    ISSN: 1432-0568
    Keywords: Cytogenetics ; Oocytes ; Development ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oocytes were isolated by mechanical disruption of the ovarian tissue of juvenile mice aged between 8 and 28 days p.p. Different types of oocytes could be distinguished by direct observation using an inverted light microscope. Their relative amount within the oocyte population isolated was determined in relation to age of the animals. The following types were isolated and examined: 1. “Normal” oocytes containing an intact germinal vesicle (that is, a nucleus in dictyate stage). In all age groups 55 to 83% of the oocytes were of this type. Their nuclear developmental stage was determined by studying their capacity to resume meiosis in culture as a function of age. 45% of the oocytes isolated from 15 day old mice were competent to resume meiosis. In mice aged 21 days more than 80% of the oocytes measuring about 80 μm in diameter resumed meiosis in vitro. No further increase in mean diameter or in the amount of competent oocytes could be found in older mice. 2. Degenerating oocytes. Five different types could be distinguished. a) “Atretic” oocytes present in all age groups investigated with pyknotic or disintegrating nuclei; b) “Precociously matured” oocytes first observed in mice aged 15 days containing normal diakinesis-and metaphase II-chromosomes; c) “Vacuolized” oocytes first isolated on day 18 having metaphase II-chromosomes scattered within the cytoplasm; d) “Fragmented” oocytes also first observed 18 days p.p. containing chromatin dissociated into micronuclei of different sizes within the cytoplasmic fragements; e) “Ghost” oocytes present in all age groups, characterized by the disintegration of the cytoplasm so that only the surrounding zona pellucida can be clearly seen.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 161 (1980), S. 19-27 
    ISSN: 1432-0568
    Keywords: Surface characteristics ; Oocytes ; Mouse ; Scanning Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The in vivo and in vitro development of the zona pellucida as well as the vitelline membrane surface of oocytes isolated from juvenile mice aged between 8 and 30 days p.p. were investigated by scanning electron microscopy. In vivo a consistent development of the zona pellucida surface can be observed, namely the formation of a fibrous network like structure interspersed with numerous pores. After enzymatic removal of the zona pellucida the surface of the vitelline membrane was studied. In “normal” oocytes with intact germinal vesicles, microvilli were distributed over the entire oocyte surface in all age groups investigated. After resumption of meiosis in vitro a characteristic differentiation on the vitelline membrane occurs. A glabrous polar region appears in primary oocytes and a glabrous polar body in secondary oocytes. The same differentiation in surface organization could be observed in the in vivo precociously matured oocytes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 39 (1983), S. 1335-1338 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several blood-sucking arthropods, after a blood meal, are able to store the hemoglobin from their hosts in a crystalline state in their digestive system5,15,20. Guinea-pig hemoglobin crystallizes in the stomach of the reduviid bugRhodnius prolixus in two different crystal types. We show them to be crystallographically identical and to contain the same liganded state of hemoglobin, i.e. they represent different habits of the same crystal modification. The hemoglobin crystallizes in oxy-form and ages in the crystalline state, first to aquomethemoglobin and subsequently to hemichrome without crystal cracking. The rate of aging appears to be the same for both types. The hemoglobin crystal modification observed in the digestive system ofRhodnius prolixus is highly host- but not parasite- specific. The same modification is also observed in vitro and inOrnithodorus moubata, an arachnid whose digestive system differs considerably from that of the insectRhodnius. The retainment period of the crystals represents a long term host-record of possible medical interest.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 40 (1984), S. 935-937 
    ISSN: 1420-9071
    Keywords: Ion secretion ; leaf surface pH ; Malvaceae ; phylloplane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary All of 19 different species of Malvaceae have high pH-values, pH 9.5 or higher, on one or both surfaces of mature leaves. This is due to the secretion of magnesium and potassium carbonate and bicarbonate. The unusual pH and ionic composition may be important for parasites and pathogens living in the phylloplane of Malvaceae.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pore structures of Amberlyst A-21 and of a polystyrene support which is cross linked with 5.6% divinylbenzene2, were investigated using the scanning electron microscope. Both polymers were found to possess a granularly structured surface. However, in Amberlyst A-21 a distinct pore structure is observed in the interior which is not found in the polystyrene support cross linked with 5.6% divinylbenzene. Accordingly Amberlyst A-21 might be macroporous while the other support, which was investigated, appears to be rather a modified type of normally cross linked polystyrene.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of orthopaedic and trauma surgery 78 (1974), S. 199-215 
    ISSN: 1434-3916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Metallimplantate (Osteosynthesematerial) aus Stahl und/oder Titan mit unterschiedlicher Oberflächenbehandlung wurden im Tierexperiment (Schweizer Bergschafe) auf ihre Gewebeverträglichkeit untersucht. Der Einfluß der Metallimplantate auf das umgebende Bindegewebe ist die Resultante aus: a) Elektrochemisches Milieu auf Grund der Metallkombination oder der Metalloberfläche. Die Oberflächenfeinstruktur der Implantate wurde mit Hilfe des Rasterelektronenmikroskopes untersucht. Sie ist bei den Stahlimplantaten, abgesehen von Korrosionsstellen, relative glatt und bei den oberflächenbehandelten Titanimplantaten orangenhautähnlich. b) Menge und Art der Metallpartikel, die sich von der Implantatoberfläche ablösen. Eine Antwort darauf gibt die Röntgenmikroanalyse. Die Bindegewebeumgebung der Stahlimplantate enthält die chtotoxischen Elemente Eisen und Chrom, die Umgebung der Titanimplantate dazu das gewebefreundliche Titan. c) Cytotoxicität der Metallpartikel. Sie wurde mit Hilfe einer morphometrischen Analyse des metallumgebenden Bindegewebes analysiert. Die verschiedenen Stahlkombinationen weisen, verglichen mit den Titankombinationen, die größere Zellreduktion im Bindegewebe auf und haben folglich auch die größere Cytotoxicität. Diese Tatsache drückt sich auch im Verhältnis der Zellzahl und der Kernanschnittsfläche aus. Diese Proportionalität wird bei den Stahlkombinationen durch eine kleinere Anzahl größerer Zellkerne und bei den Titankombinationen durch eine größere Anzahl kleinerer Zellkerne in einem konstanten Verhältnis von 1∶10 gehalten. Dies bedeutet, daß Reiz und Reizbeantwortung, wie sie durch die Metallimplantate ausgelöst werden, bei den Stahlkombinationen am größten sind.
    Notes: Summary The tissue compatibility of titanium and steel implants of different surface treatment was studied in animal experiments. The reaction of connective tissue surrounding metallic implants is the resultant of the following factors: a) Local currents due to combination of metallic material or metal surface. In the case of steel implants the ultrastructural surface studied with the aid of scanning electron microscopy is smooth, apart from some corrosions spots. In the case of surface treated titanium implants, the surface is orange peel like. b) Quantity and kind of metallic particles detached from the implant surface were studied by electron probe X-ray microanalysis. The connective tissue surrounding the steel implants contains the cytotoxic elements iron and chronium. In addition to this, the environment of the titanic implants shows titanium of good tissue affinity. c) The cytotoxicity of the particles was studied by the morphometric analysis of the metalsurrounding connective tissue. In comparison with the titanium combinations, the steel combinations show a stronger cell reduction in the connective tissue and consequently, a higher cytotoxicity. This fact is also reflected in the ratio between cell number and nuclear size. In the case of steel combinations, this proportion is maintained in a constant ratio of 1∶10 due to a smaller number of larger cell nuclei; in the case of titanium combinations due to a higher number of smaller cell nuclei. This means that stimulus and response to stimulus, such as produced by metallic implants, is most intensive in the case of steel combinations.
    Type of Medium: Electronic Resource
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