Fig. 2. (A) Section of a stage 40 transgenic Xenopus laevis embryo carrying Xrx1A-GFP construct 1 (see Fig. 3) and displaying GFP fluorescence in photoreceptor cells. (B) High magnification of a section through an eye of a stage 40 transgenic tadpole shows fluorescence in the photoreceptor layer. (C) The same section stained using antibodies against rhodopsin. (D) Overlap of B and C, demonstrating that the rhodopsin-positive rods (yellow cells) express GFP. However, some rhodopsin-negative cells also express GFP (arrowhead). (E) Additional staining with Topro-3 visualizes other retinal cells. (F) High magnification of a section through an eye of stage 40 transgenic tadpole displays fluorescence in the photoreceptor layer. (G) Staining of the same section with antibodies against calbindin, a marker of cone cells. (H) Overlap of F and G, demonstrating expression of GFP in cone cells (yellow cells). (I) Additional staining of the same section with Topro-3 visualizing other retinal cells.