Forelimbs of the newt Notophthalmus viridescens continuously denervated for up to six weeks prior to amputation do not regenerate

It has been suggested that urodele forelimbs become “addicted” to innervation, because they will not regenerate in the absence of nerves. Recently, evidence has been provided that indicates that if axolotl forelimbs are denervated for 3 or 4 wk prior to amputation, they will regenerate in the absence or near absence of nerves since the addiction is broken and regeneration can occur (Wallace, '81). The present investigation was designed to determine if forelimbs of the newt Notophthalmus viridescens could regenerate in the absence of nerves when the forelimbs were maintained in a denervated state for several weeks prior to amputation. Thus, newts had their forelimbs denervated by transection of the brachial plexus at intervals of 0, 2, 4, 6 wk prior to forelimb amputation through the radius and ulna. Denervations were repeated at 2‐wk intervals to prevent regrowth of the nerves. After amputation, the limbs were observed and the degree of regeneration observed. The results indicated that regardless of the length of the prior denervation period, denervated limbs consistently failed to regenerate. In the newt, it appears that long‐term denervation does not significantly modify the requirement for nerves during forelimb regeneration.