Figure 4. SOX9 is expressed in the adult neurogenesis region and in the retina. A, Sections of the olfactory bulb from GLT1-EGFP mice were immunolabeled against SOX9. Confocal images of the rostral migratory stream showed a lack of GLT1 (green) signal in the rostral migratory stream, whereas SOX9+ cells (purple) are densely distributed. B, In the dentate gyrus, SOX9-EGFP+ (antibody, purple; EGFP, green) cells are shown in the subgranular cell layer with their processes extending to the granular cell layer. Those cells also express GFAP (red). C, In GLT1-EGFP (green) mouse, SOX9 (purple) is highly expressed in the subventribular zone. Only a small portion of SOX9+ cells in the SVZ express GLT1. Scale bar, 50 μm. D, In the subventricular region, SOX9+ (purple) nuclei are surrounded by GFAP (red) expression. E, In SOX9-EGFP mouse, the majority of the cells in the subventricular region express EGFP (green). EGFP+ cells are also positive for SOX9 antibody labeling (purple) and are surrounded by GFAP+ fibers (red). F, In the GLT1-EGFP mouse, on the retina, SOX9+ cells (purple) are also positive for Müller glia marker GS (red). GLT1 does not label Müller glia. G, SOX9 expression in the retinal glial cells. ONL, Outer nuclear layer; INL, inner nuclear layer. Retina sections from SOX9-EGFP (green) mice were fluorescently labeled against SOX9 (purple) and GS (red) antibodies. Müller glia express both SOX9 (purple and red) and GS. Scale bar, 50 μm.