Fig. 6. Swapped domain experiments suggest that the C terminus of XOtx2 or XOtx5b is necessary in determining bipolar or photoreceptor cell fate, respectively. (A) Schematic of constructs used in lipofection experiments. N, N terminus; HD, homeodomain; C, C terminus; 2, XOtx2; 5b, XOtx5b. (B-D) Stage 41 lipofected retinas were sagittally cryostat sectioned (10 µm) after transfection with GFP and pCS2+ vector, XOtx2/5b or XOtx5b/2 during early stages of eye formation. Lines are drawn over inner and outer plexiform layers to define the laminated retina (see Fig. 4). (B) GFP lipofected retina shows all retinal cell types. (C) GFP and XOtx2/5b lipofected retinas have an increase of photoreceptor cells as do XOtx5b lipofected retinas. (D) GFP and XOtx5b/2 lipofected retinas also have an increase of bipolar cells. (E-F) Quantitative analysis of retinas lipofected with GFP and pCS2⁺ compared to retinas lipofected with (E) XOtx5b/2 and GFP (pCS2⁺, n=24; XOtx5b/2, n=30) or (F) GFP and XOtx2/5b (pCS2⁺, n=26; XOtx2/5b, n=23). The ratio of retinal cells per total retina was calculated for each retina and then the ratios averaged for the total retinas counted (n). The error bars, s.e.m.; P0.05 (Student's t-test).