Figure 6.

FGF2-mediated formation of proliferating MGPCs recruits and requires the activation of Wnt-signaling. Eyes were injected with 4 consecutive daily injections of FGF2 ± XAV939, BrdU 24 hrs after the last injection of FGF2, and retinas harvested 48 hrs (a–f) or 24 hrs later. Alternatively, eyes were injected with FGF2 alone (control) or FGF2+GSK3β-inhibitors (treated) at P7, P8 and P9, BrdU at P10 and P11, and retinas harvested at P12 (g–i). Retinal sections were labeled with antibodies to nuclear β-catenin (green) and Sox9 (red; a,b), BrdU (green), Sox9 (red), Nkx2.2 (magenta; c,d), or BrdU (green) and Sox2 (red; h,i). a,b; β-catenin in the nuclei of Sox9⁺ Müller glia/MGPCs on 70% grayscale background. Arrows indicate the nuclei of Müller glia and/or MGPCs, and hollow arrow head indicate the nuclei of proliferating NIRG cells. The histograms in e and g illustrate the mean (± SD; n=8) number of proliferating Müller glia per field of view (14,400 μm² for e, 28,800 μm² for g). The histogram in f illustrates the mean (± SD; n=8) number of Sox9-positive nuclei in the ONL per field of view (14,400 μm²). Significance of difference (*p<0.001; ns – not significant) between control and treated groups was determined by using a two-tailed t test. The scale bar (50 μm) in panel d applies to e and d, and the bar in i applies to a,b,h and i. Abbreviations: ONL – outer nuclear layer, INL – inner nuclear layer, IPL – inner plexiform layer, GCL – ganglion cell layer.