Fast axonal transport in motor nerve regeneration

This report describes the fast axonal transport of [³H]‐leucine‐labeled proteins in regenerating rat sciatic motor nerves. A normal rate of fast transport (383 ± 33 mm/day) was present in the regenerating sprouts, as well as in the central stumps. The rapidly transported proteins passed the level of axotomy without impediment, and accumulated in the endings of the regenerating sprouts, as shown by electron microscope autoradiography. In addition, transported proteins accumulated in terminal neuromas. The relative amount of protein‐incorporated radioactivity in the crest of fast transport in the regenerating nerves was increased compared to control nerves. These results are interpreted to suggest that the mechanism of fast transport is the same in regenerating sprouts as in normal axons; during regeneration fast transport appears to add newly synthesized materials to the growing tip.