Figure 1.

The mosaic arrangements of the cone inner segments and the rod and cone terminals in the adult zebrafish retina. A,B: SWS1-GFP:LWS-GFP double transgenic retina. C: SWS1-GFP:XOPS-EGFP double transgenic retina. A: Single-plane confocal image of the cone inner segment mosaic in a SWS1-GFP:LWS-GFP retina where UV cones have bright fluorescence and R cones dim fluorescence. B: The same visual field as in A but at the level of photoreceptor terminals. Note the central dark area of the R cone terminals (arrow) which likely corresponds to the large central invagination typical of fish cones (Allwardt et al., 2001). Telodendria extend out from the UV cone terminals to contact other terminals (arrowhead). C: Single-plane confocal image of a SWS1-GFP:XOPS-EGFP retina at the photoreceptor terminals. In this micrograph UV cone terminals have dim fluorescence and rod terminals bright fluorescence, and together they delineate the locations of R, G, and B cone terminals. The rod terminal also has the central dark area (arrow). D: Diagram of the typical cone terminal mosaic along with rod terminals. The double cone (R and G) terminals form double rows and the alternating short single (UV) and long single (B) cone terminals form single vertical rows; the double rows alternate with the single rows. R cone terminals flank the UV cone terminals. Within single cone rows, the B cone terminals are not equidistant to their neighboring UV cone terminals but closer to one of them (here the upper one). Within double cone rows, the orientation of each pair of R and G cone terminals zigzags (black lines). The numerous rod terminals fill in the cone terminal mosaic. R, red-sensitive cones; G, green-sensitive cones; B, blue-sensitive cones; UV, ultraviolet-sensitive cones; and Rod, rods. Scale bar = 10 µm.