Résumé :
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The techniques of ultrastructural cytology became essential in the study of peripheral nerve pathology. Light microscopic examination of semi-thin sections of epoxy resin embedded material allows to estimate the number, diameter and distribution of myelinated nerve fibres. Quantitative studies are made from microphotographs, magnified x 1,000, of an accurately determined area of about 0.1 mm2. Electron microscopic·examination of ultra-thin sections is needed to identify many lesions of axon, myelin, Schwann cell and interstitial tissue. Quantitative studies of unmyelinated fibres are made from electron-micrographs, magnified x 10,000, of an accurately determined area of about 6,000 µm2. The value of these techniques in comparison to the classical histological methods and teased nerve fibres after osmium tetroxide post-fixation is illustrated from 3 examples (amyloid neuropathy, Charcot-Marie-Tooth amyotrophy and Refsum's disease).
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