Ad-NGF administration significantly increased the accuracy of SB sensory neuron reinnervation 8 weeks post-injury. Femoral transection, adenoviral administration, and sequentially triple retrograde tracing were performed as illustrated in figure 2A. L2 – L4 DRG were processed at 8 weeks post-injury. A, The ratio of F555 to F488 labeling in FG pool corresponds to regenerating SB neuron projection between SB and MB. Ad-NGF administration significantly increased the SB neuron reinnervation to SB as opposed to MB. B, The percentage of SB neuron regeneration was not significantly changed. C, Ad-NGF administration increased SB neuron regrowth into SB, and decreased SB neuron regrowth into MB or dual branches. No significant difference was detected. SB, saphenous branch; MB, motor branch; Ad-NGF, recombinant adenovirus encoding NGF; non-Ad, non-adenovirus. Values represent mean ± S.E.M; n = 3 – 6. * p < 0.05; ** p < 0.01; *** p < 0.001 compared to sham group; # p < 0.05 compared to non-Ad group, analyzed by Students’ t-test (between only two groups) or One-Way ANOVA followed by Tukey post hoc test (among multiple groups).