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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 180 (1989), S. 237-242 
    ISSN: 1432-0568
    Keywords: Perineurium ; Lanthanum ; Diffusion barriers ; In vivo ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary While the perineurium as a diffusion barrier has been extensively investigated by light and electron microscopy, copy, such studies have been largely restricted to the use of protein tracers. In the present study the permeability of the perineurium to a physiologically more relevant ionic tracer has been assessed. In vivo the rat sural or tibial nerve was either microinjected with lanthanum nitrate solution for endoneurial application or bathed in the lanthanum solution for epineurial application. The findings generally demonstrated an effective barrier to the tracer which failed to penetrate the inner layers of the perineurium. Only at the highest lanthanum concentration and longest time intervals employed did trace quantities occasionally penetrate the barrier and then only in the presence of some cytopathological changes to the outermost perineurial cells. The usefulness of the microinjection method was limited by the slight but unavoidable trauma to the perineurium. The findings are related to those of other studies which have used electron dense tracers, also to studies using physiological including electrophysiological techniques and morphological including freeze-fracture methods.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 48 (1979), S. 95-103 
    ISSN: 1432-0533
    Keywords: Schmidt-Lanterman incisures ; Electron microscopy ; Nerve crush ; Wallerian degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The electron microscopy of changes at Schmidt-Lanterman incisures in Wallerian degeneration has been described only briefly previously. We have demonstrated that the changes up to 36 h after nerve crush are chiefly peri-incisural. At 12h and 24h ‘incisural dilatation’ consisted of an intraperiod line separation of peri-incisural myelin lamellae, which began among inner (adaxonal) lamellae extending later to outer (abaxonal) lamellae. The incisure itself showed little or no change. At 36 h, ovoid formation was apparent in most fibres. The sites of fibre cleavage to form ovoids occurred adjacent to incisures at the focal regions of myelin lamellae separation. Even within ovoids the incisures themselves remained intact at 36 h. The fine structural changes at incisures following nerve crush provide an understanding of the increased perceptibility of incisures by light microscopy during early Wallerian degeneration.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 33 (1975), S. 257-270 
    ISSN: 1432-0533
    Keywords: Perineurium ; Pathology ; Electron microscopy ; Homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The response of the perineurium to the following experimental systems was investigated by light and electron microscopy: nerve crush, cold lesion and microinjection of (a) histamine liberator, (b) potassium cyanide, (c) lysophosphatidyl choline (LPC). Where myelin breakdown occurred, lipid globules were seen within Schwann cells, macrophages and also perineurial cells. Where increased vascular permeability occurred, proteinaceous material leaked from endoneurial vessels into the endoneurial space and later appeared between perineurial laminae. It is suggested that the normal homeostatic function of the perineurium is extended in pathology to the removal of protein and lipid debris. In this way the perineurium contributes to the restoration of the normal microenvironment of peripheral nerve fibres.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 22 (1972), S. 333-344 
    ISSN: 1432-0533
    Keywords: Segmental Demyelination ; Remyelination ; Axon/Schwann Cell Relationship ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopic observations were made of early remyelination after segmental demyelination in experimental allergic neuritis (EAN) and experimental diphtheritic neuropathy. In EAN 71% of axons which had been demyelinated were invaginated each within a single Schwann cell; remyelination associated with this cellular relationship was in accordance with the spiral myelin concept, 29% of demyelinated axons in EAN were initially enveloped each by several Schwann cell processes and the associated mechanism of remyelination was by “tunication” resulting in a transient irregular distribution of myelin lamellae around the axon circumference. In diphtheritic neuropathy regeneration more closely paralleled development in ontogeny. 88% of demyelinated axons were invaginated each within one Schwann cell, only 12% of axons were each enveloped by more than one Schwann cell process. Early remyelination by tunication was not observed in diphtheritic neuropathy. Additional loosely associated Schwann cell processes lying within the “old” Schwann cell basement membrane occurred frequently in both experimental conditions. Schmidt-Lanterman clefts, “redundant” myelin, and “desmosomes” were observed in the sheaths of incipient remyelination.
    Type of Medium: Electronic Resource
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