Figure 3.

ss expression in imaginal discs. Imaginal discs from third instar larvae and pupae were hybridized with RNA probes transcribed from the XB3.2 genomic clone or the sscA6 cDNA. (A,B) Eye–antennal discs from early and late wild-type third instar larvae. In B the arrowhead indicates the maxillary palp anlage and the arrows indicate the morphogenetic furrow in the eye disc. (C) ss transcript accumulation in ss^a mutant (ss^D114.3/ss^D114.4) third instar eye–antennal discs. The pattern resembles that in the wild-type early third instar leg (cf. E). (D) ss expression in an everted antennal disc. Arrowheads indicate the boundary between the second (A2) and third (A3) segments. (Ar) The arista. (E– G) ss expression pattern in early E and late F third instar leg discs, and in a leg disc just prior to eversion (G). The arrowhead in G indicates bristle precursor cell labeling. (H) ss expression in a mature third instar wing disc. Expression is seen in an anteroventral stripe (arrowhead) and a patch in the presumptive notal region. (I) ss antennal expression in a heterozygote for the Antp gain-of-function allele Antp^73b. Variegated reduction in ss expression is seen. Scale bars, 50 μm; the bar in A refers to A– D and I; the bar in E refers to E, F, and G.