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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 48 (1979), S. 113-125 
    ISSN: 1432-0533
    Keywords: Complete cerebral ischemia ; Postischemic recirculation ; Electron microscopy ; Nuclear perturbations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal, astrocytic, and oligodendrocytic elements in several brain loci of the cat were examined at the light and electron microscopic level immediately after periods of complete cerebral ischemia (CCI) uncomplicated by post-ischemic recirculation. Such CCI episodes ranged from 1.5–25 min duration and were methodically produced in a cat model employing rigorous physiological controls. Subsequent to these CCI insults, morphological alterations occurred in a homogeneous manner within each cell type of all loci examined; however, variation in the temporal onset and magnitude of alterations among the various cell types was observed. With brief ischemic insults all cell nuclei demonstrated pronounced nuclear alterations, while their cytoplasmic organelles displayed minimal change. Chromatin clumping and nucleolar condensation were observed in both neurons and glia subsequent to 1.5–5 min of CCI, respectively. With increasing durations of CCI such changes were more dramatic and conspicuous alterations of the cytoplasmic organelles were observed. On the basis of extensive morphological analyses the present study illustrates that nuclear alterations are the first to occur subsequent to CCI. The homogeneity of neuronal involvement seen subsequent to CCI uncomplicated by post-ischemic recirculation is inconsistent with the “selective vulnerability” purported to occur by others. The significance of this inconsistency remains to be assessed; yet, the suggestion is advanced that post-ischemic recirculation may be a factor in the genesis of such vulnerability.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 106 (1995), S. 248-256 
    ISSN: 1432-1106
    Keywords: Long-term potentiation ; Traumatic brain injury ; Excitability ; Hippocampus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of traumatic brain injury (TBI) on hippocampal long-term potentiation (LTP) and cellular excitability were assessed at postinjury days 2, 7, and 15. TBI was induced using a well-characterized central fluid-percussion model. LTP of the Schaffer collateral/commissural system was assessed in vivo in urethane-anesthetized rats. Significant LTP of the population excitatory postsynaptic potential (EPSP) slope was found only in controls, and no recovery to control levels was observed for any postinjury time point. Four measurement parameters reflecting pyramidal cell discharges (population spike) indicated that TBI significantly increased cellular excitability at postinjury day 2: (1) pretetanus baseline recording showed that TBI reduced population spike threshold and latency; (2) tetanic stimulation (400 Hz) increased population spike amplitudes to a greater degree in injured animals than in control animals; (3) tetanus-induced population spike latency shifts were greater in injured cases; and (4) tetanic stimulation elevated EPSP to spike ratios (E-S potentiation) to a greater degree in injured animals. These parameters returned to control levels, as measured on postinjury days 7 and 15. These results suggest that TBI-induced excitability changes persist at least through 2 days postinjury and involve a differential impairment of mechanisms subserving LTP of synaptic efficacy and mechanisms related to action potential generation
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 149 (1977), S. 439-452 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Blood vessels of the human telencephalic germinal matrix during the tenth through the twenty-second week of gestation have been examined by light and electron microscopy. In all fetuses studied the ependymal and sub-ependymal zones of the germinal matrix have a prominent vascular network. During the tenth and twelfth weeks of gestation, the endothelial cells are plump and display numerous organelles, junctional complexes, conspicuous luminal microvilli and stub-like abluminal projections. Coated and micropinocytotic vesicles were found both in the cytoplasm and on luminal and abluminal surfaces. In endothelial cells intracytoplasmic, membrane-limited, rod-shaped bodies were frequently observed. These bodies have been linked to endothelial thromboplastic and clotting activities and related to abnormal clotting status. Their role in the pathogenesis of subependymal germinal matrix hemorrhage in premature infants remains unknown. Pericytes apposing the endothelial cells were recognized in all gestational periods. The endothelial basal lamina and astrocytic end-feet are ill defined, and the extracellular space is pronounced. By the fifteenth and seventeenth weeks of gestation the endothelial cells are still large and now possess more numerous luminal microvilli and abluminal projections. At this stage the pericytes, basal lamina and astrocytic end-feet are all well developed, resulting in a decrease in the surrounding extracellular space. By the twenty-second week the endothelial cells possess few luminal and abluminal projections and the associated basal lamina, glia, pericytes and extracellular compartment appear mature. The relationship of the germinal matrix vasculature to the pathogenesis of subependymal hemorrhage is discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The pineal gland of the 13-lined ground squirrel (Citellus tridecemlineatus) has been examined at the light and electron microscopic level. This gland is composed of low-density parenchymal cells interspersed among which are occasional glial, vascular and neural elements. Punctuating the glandular parenchymal mass are prominent perivascular and intercellular spaces.The parenchymal cells possess numerous mitochondria and less prominent profiles of rough and smooth-surfaced endoplasmic reticulum. Golgi apparatus, microtubules and lipid droplets of varying size and electron density constitute regular cytoplasmic features, with dense-core vesicles being present occasionally. The parenchymal cells have numerous processes. One among these in each cell extends for several micra to terminate in a bulbous expansion containing both clear and dense-core vesicles and occasional electron-dense inclusions. These bulbous terminals are found within the perivascular and intercellular spaces where they course in close proximity to both other parenchymal elements and axon terminals. Glial cells and their processes invest the pineal periphery and incompletely separate the parenchymal cells.
    Type of Medium: Electronic Resource
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