Immunocytochemical distribution of sodium channel immunoreactivity in the goldfish retina. A, Staining using a pan-specific sodium channel antibody was most prominent in small cell bodies in the INL, a thin band in the OPL, a broad band in the IPL, cell bodies in the GCL, and bright spots in the proximal retina and optic fiber layer, which likely represent cross-sections of optic nerve fibers. B, All staining was abolished after overnight preadsorption of the primary antiserum with peptide antigen.C, D, Double-labeling showed that PanNaCh-IR (C) was colocalized with PKC-IR (D; a marker for ON type bipolar cells) in small cell bodies in the INL (asterisks) that had dendrites directed to the OPL (C, double arrowheads). These double-labeled cells were ON type cone bipolar cells. The large PKC-IR mixed rod–cone bipolar cells, type Mb (D, arrowheads), were never PanNaCh-IR. In addition, PanNaCh-IR was found in apparent cone bipolar cells that were not PKC-IR (C, arrows), nor were all PKC-IR cone bipolar cells labeled with PanNaCh-IR (D,arrows). OPL, Outer plexiform layer;INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer. Scale bars, 25 μm.