Fig. 3. Features of rod cells expressing EGFP. (A) Transmission image of a small piece of Xenopus retina in the recording chamber. (B) Three-dimensional rendering of CLSM scans of the piece of retina shown in A. The scan data are displayed using a linear gradient over the lower 50% of the fluorescence range to enhance visibility of weakly fluorescing rods. (The rod identified by the arrow in B is singled out for further analysis in Fig. 4A. The red arrows point to a small area of high fluorescence, a feature examined in Fig. 6.) (C,D) An outline of each rod identified in the 3D rendering was made: rods nearer the chamber floor have been outlined in red, while those further back in the stack have been outlined in yellow. In panel C these outlines have been superimposed on the transmission micrograph, illustrating the correspondence between the two images.