The microglial/macrophage response is attenuated in old zebrafish. (A) The number of microglia/macrophages in the lesion area in old zebrafish is similar to that of age-matched unlesioned controls and significantly different from young zebrafish at 4 dpl (p < 0.05, n = 5-6 fish, Kruskal Wallis test, Dunn’s post test). Representative images of old zebrafish are shown in (B); for images of young zebrafish, please refer to Figure 1C. Dashed lines outline optic nerve. Mean ± SEM. Scale bar: B = 100 μm.