The consequence of delayed versus immediate nerve repair on the properties of regenerating sensory nerve fibres in the adult rat.

Transected saphenous neurones were allowed to regenerate for 3 months via distal stumps of sural nerve following an immediate or a 3 month delayed repair. The number of DRG neurons surviving following the 3 months regeneration period were approximately 60% of normal after both immediate and delayed repair. The percentage of DRG cell bodies identified by the application of Fluro-gold proximal to the repair site and immunopositive for SP, CGRP and galanin was increased following both early and delayed repair compared to baseline values. These values were not significantly different for early repair compared to late repair. Similarly, peripheral measurements of SP in the proximal stump of saphenous nerve (by radioimmunoassay) were not significantly different between models with primary repair compared to delayed repair. These results suggest that the intrinsic regeneration properties of primary sensory neurones are not impaired when repair is delayed.