SUMMARYThis study is a comparison of retrograde degenerative features in central and peripheral nervous systems in the same animal. Although obvious retrograde reaction was seen in Nissl stain, the TPNH diaphorase reaction showed an increase in the perikarya of neurons with axons outside of the central nervous system and a decrease in the perikarya of neurons confined to the central nervous system. The results suggest that increased oxidative enzyme activity implies metabolic efforts toward regeneration, while decreased activity reflects the lack of significant regenerative attempts. The data are insufficient to conclude whether or not chromatolysis itself is a reflection of regeneration or degeneration.