Fig. 3. drm and odd regulate hh expression, probably through enabling bowl function. (A,B) Eye discs containing M+ clones mutant for (A) drm⁶ or (B) DfdrmP2 (marked by absence of lacZ). (A) No effect on retinogenesis or Ptc expression is seen adjacent to drm-mutant margin. (Similar results were obtained for odd⁵.) (B) Retinogenesis fails when the adjacent margin is mutant for DfdrmP2. White and red arrows indicate mutant and wild-type margin, respectively. (C) Adult head from the DfdrmP2, M+ experiment showing severely reduced eyes. (D,D') drm-expressing clone (absence of CD2, and outlined in D') induces an ectopic furrow (marked by dpp-Z) and associated retinogenesis (detected by Elav). The line indicates the position of the endogenous furrow (D). (E) Disc proper (Dp) expression of bowl mRNA is detected anterior to the furrow (line) in late L3 discs. (F-F") drm⁺ bowl^- clones (blue) do not induce ectopic retinal differentiation anterior to the morphogenetic furrow (arrow; line indicates the furrow). Phalloidin stains actin. A drm⁺ bowl^- clone located immediately after the furrow (boxed) shows Elav-positive neurons (inset). (G-G") L2 eye disc from oddZ/UAS-GFP; hh-GAL4 larvae shows extensive overlap of hh and odd at the posterior margin. Asterisk indicates the hh ocellar domain, which, at this stage, does not express odd-Z. (H-H") Most drm-expressing clones (absence of CD2, outlined in H' and H'') induce hh-Z expression just anterior to the morphogenetic furrow (line). Discs are oriented with posterior towards the right and dorsal upwards.