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  • 1985-1989  (2)
  • 1960-1964
  • Blood-brain barrier  (1)
  • Hypophyseal pars tuberalis  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 73 (1987), S. 349-356 
    ISSN: 1432-0533
    Schlagwort(e): Blood-brain barrier ; Cortex ; Lanthanum tracer ; Potassium ; Ion-selective micro-electrode
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Using lanthanum nitrate as a tracer, the permeability of rat cortical blood vessels was investigated during regional hypothermia of the cerebral cortex by electron microscopy. The concentration of K+ ions in the extracellular space of the cortex was determined using an ion-selective micro-electrode. Only at temperatures below about 7°C was an extravasation of tracer observed in a number of cortical capillaries and arterioles, where some of the tight junctions became widened and permeable. In a few cases penetration of the tracer into vacuoles of phagocytosing pericytes or macrophages was found. The extravasation of the tracer could mainly be observed in vessels on and below the cortical surface, less often in deeper cortical parts. At the same degree of hypothermia, the K+ concentration in the extracellular space increased, reaching a maximal value of ca. 6 mmol/l at a depth of about 200 μm. As could be shown in one previous experiment, the K+ concentration reached normal values again after rewarming to 37°C for 15 min, but an extravasation of the tracer was still observed. The role of the endothelial tight junctions and of the astrocytes together with the pericytes (or macrophages) is discussed regarding their importance for the effectiveness of the blood-brain barrier system.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0878
    Schlagwort(e): Hypophyseal pars tuberalis ; (TSH), Thyrotropin ; Immunocytochemistry ; Photoperiod ; Phodopus sungorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Specific secretory cells in the hypophyseal pars tuberalis of Djungarian hamsters maintained under different photoperiods were investigated immunocytochemically by means of the colloidal gold technique using antibodies against rat thyrotropin (TSH). Secretory cells of animals kept under long photoperiods (LD16:8) showed positive staining of secretory granules (diameters 90–130 nm), whereas other intracellular structures were free of immunoreactivity. In animals kept under short photoperiods (LD8:16) secretory cells displayed increased numbers of secretory granules, but these organelles were devoid of immunoreactivity. In contrast, immunoreactivity of thyrotropes in the pars distalis did not differ between the two groups of animals investigated. The present results confirm earlier light-microscopical studies that in the pars tuberalis specific secretory cells show TSH-like immunoreactivity; however, they differ in their reactivity pattern from classical thyrotropes in the pars distalis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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