Spinal cord white matter injury after single and repeated ischaemia/reperfusion observed by a light microscope

Using a light microscope, changes in the white matter of the lumbar spinal cord segments were studied in rabbits subjected to 25 min of single ischaem ia followed by 24 h recirculation and the results were compared with those after 8-8-9 min of repeated ischaemia followed by 3 x 1 h recirculation. Se ctions were stained by the pyronine-methyl green method and semi-thin secti ons were stained by cresyl violet. These sections revealed only negligible changes in the myelinated nerve fibres after a single 25 min ischaemia and 24 h recirculation. The degree of ischaemic injury was considerably increas ed when ischaemia was repeated three times at periods of 8-8-9 min and at 3 x 1 h of interischaemic recirculation Intervals. The Light microscopic obs ervations revealed a pronounced degree of myelinolysis. The main histopatho logical changes visible after repeated ischaemia with a short interischaemi c interval were large, irregular intramyelinic dilatations, the vesicular d isruption of the myelin sheath, and conspicuous periaxonal edema accompanie d by a peripheral displacement of axons within the myelinated nerve fibres.