Figure 2. Retinal eGFP expression after subretinal delivery of an AAV-9.CMV.eGFP vector in a 3-month-old C57BL/6J mouse. AAV-9 led to widespread (from the injection site, which is close to the posterior pole, to the peripheral retina) and throughout (from the outer retina RPE layer to the inner retina RGC layer) eGFP expression in the mouse retina. The eGFP expression pattern near the injection site and in areas remote from the injection site was similar. The pictures were taken at approximately 300 to 500 µm away from the injection site. A-C were taken under the same exposure conditions. D-H were taken with a shorter exposure time. A is a section from a control eye. B shows eGFP expression in the retina, and C is a merged picture of B and DAPI staining. B and C show GFP expression in the RPE, photoreceptors (including the outer and inner segment), ONL, OPL, Müller cells in the INL, IPL and RGC layer. Because of a shorter exposure time (D), eGFP expression was only seen in the outer retina including RPE and the photoreceptor layer. No expression was observed in the inner retina. E is a merged picture of eGFP expression and CtBP2, DAPI staining. In the distal portion of the OPL, colocalization of eGFP expression and CtBP2 staining is evident (arrow). F, G, and H are enlarged pictures of the OPL. F. eGFP expression is evident in the distal portion of the OPL, which is beyond the photoreceptor nuclei (in blue). G shows CtBP2 staining (arrow) in the photoreceptor terminals. Panel H is a merged picture of eGFP expression and CtBP2, DAPI staining. eGFP expression overlaps with CtBP2 in the photoreceptor terminals in the distal portion of the OPL The calibration bar is 50 μm for A-E, and 20 μm for F-H. Abbreviations: inner nuclear layer (INL), inner plexiform layer (IPL), outer nuclear layer (ONL), outer plexiform layer (OPL), retinal ganglion cell (RGC), retinal pigment epithelium (RPE).