ANALYSIS OF HISTOGENESIS AND REGENERATIVE ABILITY OF DENERVATED FORELIMB REGENERATES OF TRITURUS VIRIDESCENS

Forelimb blastemata of the adult newt, Triturus viridescens, were denervated at three stages of regeneration and allowed to differentiate in the absence of nerves. Some of these limbs, after developing to specific regenerative ages, were subjected to hand amputations and second denervations. The central question posed was: if the blastema is allowed to differentiate in the absence of nerves, will the resultant limb upon reamputation at a more distal level be capable of initiating renewed regeneration as are aneurogenic larval limbs that have differentiated in the absence of nerves? The older the blastemata at the time of the first denervation, the greater was the incidence of continued morphogenesis. Preliminary histogenesis at the time of the first denervation did not insured continued morphogenesis, nor did complete absence of histogenesis prevent further development. Cartilage elements and muscle differentiated in nerveless regenerates, but both tissues lagged in development compared to those of the contralateral innervated limb. Muscle was reduced in amount, and some evidence indicated that it underwent degenerative changes if the nerveless state was maintained. None of the completely nerve‐free regenerates was able to reinitiate regeneration. Thus blastemal cells were not able to return to the embryonic level of independence of nerve supply under the conditions of the experiment. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company