Fig. 1. Whole-mount in situ hybridization to imaginal discs. Wing and leg discs were hybridized with probes derived from genes predicted to have elevated expression in wing discs (A-J) or leg discs (A'-J'). (A) Ect3 probe stained distinct cell clusters in the presumptive dorsal hinge region of the wing disc; (B) pdm2 probe labeled cells surrounding the pouch with preferential expression in anterior cells; (C) Phk-3 probe labeled several domains in the hinge and notum region; (D) CG4914 expression is enriched throughout the wing disc with highest levels in the dorsal-most region. (E) regucalcin probe produced signal in a population of hemocytes that are associated with the wing imaginal disc, but not the leg imaginal discs (E'). Except for Phk-3, which is expressed in a distinct cell cluster in a ventral position of leg discs, these `wing-specific' genes did not hybridize at detectable levels to leg discs (A',B',D',E'). rho, fd96CB, unc-4 and CG7447 generated more intense staining in leg discs (F',G',H',J'). rho and unc-4 are also detected in wing discs (F,H), whereas no signal above background could be detected for fd96Cb and CG7447 in wing discs (G,J). Dorsal is upwards for all discs; anterior is leftwards.