Figure 3. Incursion and morphological change in outer retinal macrophages from WT and C3 KO mice following a time course of PD. A–F: Representative retinal cross-sections fluorescently immunolabeled with IBA1 (green) and bisbenzamide (blue), in the 5- and 7-day PD groups. In the dim-reared retinas (A, D), IBA1-positive outer retinal macrophages were not present in either the wild-type (WT) or C3 knockout (KO) groups. After either 5 or 7 days of PD, a substantial incursion of macrophages was observed in the outer retina of the WT mice (B, C), which appeared less frequently in the C3 KO mice (E, F). G: Quantification of the average number of IBA1-positive outer retinal macrophages showed a statistically significant reduction in the C3 KO mice compared to the WT mice at the 5- and 7-day time points (p<0.05) but not at 1 or 3 days (p>0.05). H–I: Representative retinal cross-sections fluorescently immunolabeled with IBA1 (green) illustrate differences in the abundance of ameboid (H, arrowheads) and ramified (I, arrowhead) morphology in outer retinal macrophages in the WT and C3 KO mice after 7 days of PD. J: Quantification of ameboid and ramified IBA1-positive outer retinal macrophages at 7 days of PD revealed a substantial reduction in ameboid cells in the C3 KO mice compared to the WT mice (p>0.05). There was no statistically significant difference in the number of ramified IBA1-positive cells in the outer retina (p>0.05). Statistical significance was ascertained with two-way analysis of variance (ANOVA) with multiple comparisons (n = 6 per group; asterisks denote p<0.05). Scale bars represent 100 μm, unless indicated otherwise. INL, inner nuclear layer; ONL, outer nuclear layer; PD, photo-oxidative damage. Panel A is adapted from [42].