Fig. 6. Dpp signaling is enhanced by Sxl. (A-C) Wild type. (D-O) Male (D-F,M-O) and female (G-L) discs expressing Sxl in the dorsal compartment by ap-GAL4 driver, stained for ß-gal (green; reports Dpp through a dpp-lacZ transgene) and Sal (red; induced by Dpp). (C,F,I,L,O) Merged images. In all panels, the arrowheads mark the dorsoventral compartment boundary. The zone of Dpp expression widens in the dorsal compartment in males (D and M), less so in females (G and J). Below the dorsoventral boundary of the wing pouch is a widened zone of Dpp expression and corresponding widening/intensity of Sal expression compared with the ventral half. Arrow in I indicates slightly distorted dorsal half; (J-O) dorsal wing pouch halves have an extra fold from the increase in size (arrows). Arrow in M indicates the wing pouch–notum boundary and arrow in N indicates the edge of fold in the distended wing pouch. Scale bars: 20 µm in A-L; 40 µm in M-O. Anterior is towards the left, ventral is towards the top. Confocal images throughout.