Time course of axotomy-induced changes in choline acetyltransferase activity in the spinal cord (open squares) and ventral root (open circle). The ratio of ChAT specific activity on the left (experimental) side divided by that on the right (control) side is multiplied by 100 and plotted on the ordinate. Results for sham-operated animals at day 20 are represented by the overlapping filled symbols. Symbols represent the mean of at least 4 separate experiments involving different animals, and the vertical bars indicate the SEM where this is larger than the size of the symbol. Data were analyzed by analyses of variance, and the means from operated animals were compared to those from unoperated animals by the least significant difference method of Steel and Torrie (1960). *p < 0.05; **p < 0.01; ***p < 0.005.