Fig. 2. dally and dly are required for Hh signalling in wing development. (A-C) Wings are oriented proximal towards the left and anterior upwards. (A) wild-type wing with labeled longitudinal veins. (B) A wing carrying clones of dally⁸⁰ showing a partial L5 vein loss (arrow) (80%, n=100). (C) A wing carrying clones of dally⁸⁰-dly^A187 mutant cells showing L3-L4 vein fusion (arrow) (10%, n=80). (D-J') All the wing discs were derived from third instar larvae. Anterior is towards left and dorsal is upwards in all the wing disc images. (D-F') Ptc expression (red) in a wild-type wing disc (D) and a disc carrying a dally⁸⁰-dly^A187 clone (E,E',F,F'). In wild-type disc, Ptc is expressed in a stripe of cells abutting the AP boundary in response to Hh from the P compartment. Ptc expression is reduced in dally⁸⁰-dly^A187 mutant cells (marked by the absence of GFP in E' and F'). (G-H') En (red) staining in a wild-type wing disc (G) and a disc bearing dally⁸⁰-dly^A187 clones (H,H'). En expression in the A compartment is induced by Hh in a three to four cell diameter stripe (bracket) anterior to the AP boundary (marked by a broken line in G). This expression is eliminated in the dally⁸⁰-dly^A187 clone (marked by the absence of GFP in H'). (I-J') Col (red) staining in a wild-type wing disc (I) and a disc bearing dally⁸⁰-dly^A187 clones (J,J'). Col is expressed in four cell diameters anterior to the AP boundary. In dally⁸⁰-dly^A187 clones (marked by the absence of GFP in J'), Col is restricted to two cell diameters with a lower level in the more anterior row of cells.