Further experimental evidence of selective nerve regeneration in aortic Y-chambers.

To explain the discrepancy between Weiss and Taylor's results and our recent findings about axonal growth patterns in a fresh aortic chamber, we examined whether regenerating axons show preferential growth toward a nerve piece in an aortic Y-chamber. In our previous studies, we could not reproduce their results, which showed that regenerating nerve fibres from the proximal stump of a severed peripheral nerve grew randomly in the two channels with and without a nerve segment; our results showed preferential regeneration toward a nerve segment channel. In the present study, we retraced the steps of Weiss and Taylor using white rats, the longitudinal section of the specimen, and silver staining. Despite using the same methods we were still unable to show that the growth pattern was random, but we did find preferential axonal growth into the nerve segment channel of a fresh aortic Y-chamber. The evidence of selective nerve regeneration was unequivocal and we cannot support the findings of Weiss and Taylor reported in 1944.