Figure 1. XLPRA1-affected retina: immunohistochemical characterization of different severity phenotypes. A–D: Hematoxylin and eosin (H&E)–stained retinal cryosections from the superior quadrant (6,000 μm from the ora serrata; area is approximately the midpoint between the disc and the ora serrata) in dogs of comparable ages that have different phenotype severity. E–H: Double immunolabeling with RHO and GFAP antibodies. I–L: Double immunolabeling with hCAR and M/L opsin antibodies. Where appropriate (E, F, I, J), the immunolabeling images show the individual blue, green, and red channels with the merged image on the right of each set to show the mislocalization of opsin (*). RPE= retinal pigment epithelium; PR = photoreceptors; ONL = outer nuclear layer; OPL = outer plexiform layer; INL = inner nuclear layer; IPL = inner plexiform layer; GCL= ganglion cells layer.