Figure 4

Microglial activation after selective Müller cell ablation. Immunohistochemistry was performed using an Ab against ionized calcium-binding adaptor molecule 1 (Iba-1, green) for microglia and nuclei were counterstained with Hoechst (red) to reveal retinal structure. (A) Control (Ctl) mice showing “resting” microglia cells in the ganglion cell layer (GCL), inner plexiform layer (IPL) and occasionally the outer plexiform layer (OPL), but not in the outer nuclear layer (ONL) or the subretinal space (SP). (B-F) Activation of microglia cells was observed in transgenic (TG) mice as early as 1 day (1d, B) after TMX-induced Müller cell ablation, as reflected by increased soma size and thickened cell processes in the inner retina (B-F, arrows). Microglia cells were observed in the subretinal space from 1d and frequently seen from 7d after TMX treatment (B-F, arrowheads). Note: protrusion of photoreceptor nuclei into the subretinal space in (D-F) and obvious thinning ONL in (F) 3 months (3 m) after TMX-induced Müller cell ablation. Scale bars: A-F, 50 μm.