A, B) Immunohistochemical labeling for NKA (green) in adult Xenopus laevis retina B) higher magnification of labeled photoreceptors shown adjacent to transmitted light image. Transgenic X. laevis tadpoles expressing C) GFP-NKA α3, D) GFP-NKA α1, or E) GFP-NKA α4 in rods. Nuclei labeled with Hoechst. Abbreviations: OS, outer segment; IS, inner segment; CP, calycal processes; ONL, outer nuclear layer; N, nuclei; OPL, outer plexiform layer; ST, synaptic terminal; INL, inner nuclear layer; IPL, inner plexiform layer; GC, ganglion cell layer.