Figure 2. The sigma-1 receptor distribution in the mouse retina. A: Immunostaining of the σR1 (green) in the WT mouse retina. B: Immunostaining of the σR1 in the Sigmar1^−/− mouse retina (negative control). C and D: The Nomarsky image superimposed with the staining images in A and B, respectively. The abbreviations of the distinct cell layers are: OS, outer segment; IS, inner segment; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer, IPL, inner plexiform layer; GCL, ganglion cell layer. Synaptophysin was stained (red) to mark the presynaptic terminals in the OPL and IPL. Immunostaining of the σR1 was performed on the mouse retinal cryosections using the antibody raised against the full-length σR1 [6,32], followed by incubation with the Alexa-488 conjugated goat-antirabbit antibody. WT and Sigmar1^−/− mice of the same age (3 months) were used for preparation of retinal sections. Images were taken on a Nikon A1R laser confocal microscope and processed using Adobe Photoshop.