Figure 5. Distribution of rhodopsin relative to egr-1-d2EGFP transgene expression. Representative fluorescence microscopic images of transverse sections of adult rat retina showing detection of total cells (DAPI staining), and immunoreactivities for d2EGFP (green fluorescent protein, GFP) and rhodopsin. Animals were killed at 24:00 h. A: Low magnification image showing the massive abundance of rhodopsin protein in the outer segment (OS) region that obscures visualization of (OS) GFP. Note that exposure of the “red” fluorescence signal is minimized in this image (relative to B and E) such that the much lower level of rhodopsin fluorescence in the ONL is not detectable. Bar=50 μm. B-E. Relative expression of rhodopsin and GFP across the ONL; note the relative abundance of GFP in the inner zone of the ONL, which is indicated by a bracket (}), whereas rhodopsin is expressed at similar abundance across the extent of the ONL. Bar=20 μm. Abbreviations: OS, photoreceptor outer segment; IS, photoreceptor inner segment; ONL, outer nuclear layer; INL, inner nuclear layer; GCL, ganglion cell layer.