Fig. 2. Eye imaginal discs mutant for argos or canoe exhibit defects in ommatidial rotation. Panels show a dorsal field of third instar eye imaginal discs, anterior is left and dorsal up. Discs in A,B are double-stained with anti-Elav (red; all photoreceptors) and svp-lacZ (green; marking R3/R4 and R1/R6). (C-F) Double-labeled with anti-Bar (red; labeling R1/R6) and anti-Boss (green; marking R8). With these markers rotation angles can be unambiguously determined and are schematically shown with arrows below each panel (arrows are drawn according to Fig. 1C). (A,C) wild-type, (B,D) aos^rlt/aos^rlt, (E) aos^w11/aos^w11. Note misrotations in both aos alleles. (F) cno^mis1/cno^mis1. Discs were costained with anti-Elav to ensure that rotation abnormalities are not because of photoreceptor loss (blue channel, not shown).