Fig. 4. The hedgehog eye enhancer drives expression in all photoreceptors except for the R8 photoreceptor. Third instar eye imaginal discs, anterior rightwards. The fields shown are just posterior to the furrow. A-D and E-H are the same fields in the same eye discs. Genotypes are shown on the left; antigens are shown below; colors as indicated. Elav marks all photoreceptor nuclei (A,D,E,H;, Senseless (Sens) marks only the R8 photoreceptor nuclei (B,D,F,H); lacZ reporter (C,D,G,H). Black arrows indicate a Sens positive R8 nucleus in a single ommatidium. White arrows (B-D) mark R8, 2 and 5 as indicated. Both the 1.9 kb full-length bar3:lacZ (A-D) and the minimal 203-bp bar3L2:lacZ (E-H) have indistinguishable lacZ expression patterns. There is no LacZ expression in the R8 photoreceptor. Scale bar: 10 µm.