Figure 1.

Adult mouse RGC axon response to optic nerve injury. A, YFP-labeled RGC axons at the ONH at different intervals after nerve injury. The numbers at the bottom right represent the days after injury. UI, Uninjured. Individual images represent a composite three-dimensional stack of confocal images collected at 1 μm intervals from 50-μm-thick sections. The retina is toward the left. B, Appearance of YFP-labeled RGC axons in the uninjured optic nerve (UI) and RGC axons in the margin region at 4, 8, 12, and 18 d after injury. C, Graph showing the mean number of RGC axons per tissue section at the ONH before and at various times after injury. The numbers in parentheses represent the number of tissue sections analyzed. The data set of this graph contained a statistical difference (Kruskal–Wallis test; p = 0.0002). Tukey tests showed that the results from days 2–18 were each significantly different from the data from the uninjured nerve (differences of the mean, 11.7–17.4; 95% confidence intervals, 2.1–27.4. D, Graph showing the mean number of RGC axons per tissue section in the margin region adjacent to the injury site at various times after injury. The data set forming this graph contained a statistically significant difference (Kruskal–Wallis test; p = 0.0001). The numbers in parentheses represent the number of tissue sections analyzed. The asterisks indicate that the results from days 8, 12, and 18 were each statistically different from that from days 2 and 4 (pairwise comparisons by Tukey tests; differences of the mean, 9.8–18.7; 95% confidence intervals, 0.065–28.1). E–L, Higher-magnification views of the endings of RGC axons after optic nerve injury. The different morphologies have been arranged left to right in increasing apparent complexity. E, F, Turning axons. G, Axons with 180° loops (arrows). H, Axon with a 270° loop (arrow). I–L, Axons with complex branching morphology. Scale bars, 50 μm. Error bars indicate SEM.