Ultrastructure of the Ranvier's node in vincristine neuropathy.

Paranode-node-paranode regions of the nerve fibre interact in a fundamental manner with the transport of axoplasmic material. The aim of the study was to examine the ultrastructure of Ranvier's node in sciatic nerve of rabbits treated with vincristine. The results showed accumulation of organelles in Ranvier's nodes of affected animals. Organelles arrested in this region disturbed each other and degenerated. Some of them were sequestered from the axon by Schwann cell fingers and terminal loops, but often this process was not sufficient to prevent nerve fibre against degeneration. In conclusion our results provided evidence that Ranvier's node become locus minoris resistentiae in vincristine affected nerve fibers.