Journal of Neuroscience, Vol 2, 1793-1811, Copyright © 1982 by Society for Neuroscience
Regeneration and functional reconnection of an identified vertebrate central neuron
MT Lee
I have examined the axonal regeneration of a pair of identified central
neurons, the Mauthner (M) neurons, in Xenopus laevis tadpoles. Lucifer
Yellow injections reveal regenerative sprouts arising from the proximal
stumps of the M axons within a few days after axotomy; some of these can
cross the lesion within 1 week. Many specimens examined at later times (up
to 21 weeks) have processes that extend more than 2 mm (equivalent to 5 to
10 spinal segments) beyond the lesion. M axons which have regenerated
caudal to the lesion can re-establish functional synaptic contacts with
their normal targets, spinal motor neurons. Functional reconnection has
been demonstrated as early as 9 days after axotomy and as far as 10
segments caudal to the lesion. In most of the specimens tested, the
regenerating M axons appear to exhibit the same degree of specificity for
appropriate postsynaptic targets as normal, untransected M axons. M axons
retain the ability to generate throughout the range of stages included in
this study. The results provide evidence that a return of normal function
in the transected vertebrate spinal cord can be mediated by the
reconnection of a regenerating neuron with its normal targets.