Transneuronal effects on amphibian limb regeneration.

Abstract

AbstractThis investigation has demonstrated that in both the newt and axolotl the simultaneous removal of a second limb brings about a significantly slower linear regeneration rate, but only if the second limb removed is directly contralateral to the first one removed. Both morphologic and autoradiographic data point to a more prolonged chromatolysis in the brachial neurons following contralateral forelimb removal. This is thought to bring about the slower regeneration rate seen. Further evidence for this contention is the fact that just the severance of the brachial nerves of one forelimb of an animal will bring about a significantly slower regeneration rate of the contralateral forelimb. In salamanders without intervening nervous connections or CNS tissue between the limbs, i. e., the aneurogenic larvae, no effect on regeneration rate is seen following contralateral double limb removal. Autoradiographs using 3H thymidine as a precursor point to an early effect on growth as being the means that contralateral denervation or limb removal brings about a slower regeneration rate. This is thought to be due to a decrease in the trophic ability of the brachial innervation following the more profound disruption of the brachial neurons that accompanies double limb removal.