Representative fluorescence photomicrographs of L4 DRG neurons. (A) FG-labeled DRG neurons, (B) ATF3-ir DRG neurons, and (C) GAP43-ir neurons. (D) Distribution of FG-labeled ATF3-ir GAP43-ir DRG neurons. The scale bars are 50 μm. All photomicrographs are from the same section. The cytoplasm was immunopositive for FG and GAP43, whereas the nuclei were immunopositive for ATF3. The arrow indicates the same DRG neuron is positive for FG, ATF3-ir, and GAP43-ir. (D) Merged image acquired from Figures 4(B) and 4(C). In ATF3-ir GAP43-ir DRG neurons, the nuclei and cytoplasm are stained green and red, respectively (E) The average numbers of the FG-labeled ATF3-ir/ATF3-irGAP43-ir DRG neurons. The number of the appropriate cells was small but increased significantly after 14 days post-injection (F) The number of FG-labeled ATF3-ir DRG neurons was significantly increased in the ipsilateral MIA-treated knees (P < 0.05), and these neurons were significantly more prevalent 14 days after MIA injection (P < 0.05). FG-labeled ATF3-ir and GAP43-ir DRG neurons showed a similarly significant temporal increase (P < 0.05). There were no ATF3-ir or ATF3-ir GAP43-ir neurons in the contralateral side.