Electron microscopic study of the early changes proximal to a constriction in myelinated nerve.

An ultrastructural study has been carried out of the changes observed proximal to a nerve constriction in rabbits. The lesion was experimentally produced with a silk ligature. Specimens were examined 24 h after ligation. Significant alterations of the ultra structure were found in sections taken at approximately 1 mm above the constriction. Examination revealed swelling of the nerve fibres due to failure of axoplasmic flow, a marked increase in the number of mitochondria, most of which showed degenerative changes and degenerative changes in the myelin sheath.