Fast axoplasmic transport in the fibres of chromatolysed neurones.

1. The rate of fast axoplasmic transport in cat sensory nerves was determined in sciatic nerves above transections made low in the popliteal fossa some 6-165 days beforehand. The pattern and rate of movement of the crest of labelled components in the nerve fibres after injecting the L7 dorsal root with [3H]leucine was used to characterize fast axoplasmic transport. 2. The mean rate and S.D. found on the transected side was 424 + 33 mm/day compared with 432 +/- 34 mm/day for the control nerves. These rates were not significantly different and were similar to the rate of axoplasmic transport previously reported to be 410 +/- 50 mm/day. The results gave little support for the hypothesis that a speeding up of the rate of fast axoplasmic transport is the signal for the initiation of chromatolysis. 3. The amount of transport shown by the level of activity in the crests on the chromatolytic and control sides relative to the "pool" of radioactive materials remaining in the cell bodies of the ganglion were also similar. The significance of these findings was discussed with respect to changes in the cell bodies known to take place during chromatolysis and the stability of the axoplasmic transport mechanism in nerve fibres.