The influence of flank dermis on limb regeneration in the newt, Notophthalmus viridescens

The ability of nonlimb skin to support forelimb regeneration was studied in the newt, Notophthalmus viridescens. When forelimb skin was replaced by skin removed from the flank followed by amputation through the graft, 96% of the limbs did not regenerate. Varying the orientation of the skin graft around the limb did not affect this outcome. When limb stumps were covered by flank epidermis independent of flank dermis, normal forelimb structures regenerated (86%). When flank dermis was grafted to the limb independent of flank epidermis, 66% of experimental limbs did not regenerate. When flank skin was grafted proximal to the regenerate at several times after amputation (3, 9, or 15 days), 72% of the experimental limbs did not regenerate. Finally, limb stumps that contained no dermis at the level of amputation underwent normal regeneration (86%). These results indicate that flank skin does not support forelimb regeneration in the newt. The dermal component of flank skin is responsible for this outcome.