Fig. 7. Local requirements of Wg and Egfr signalling for posterior spiracle organogenesis. Effects of Wg and Spi^S expression in spiracular chamber or stigmatophore cells on the morphology of the posterior spiracle. ems-Gal4/UAS-wg (A,A') or ems-Gal4/UAS-spi^S (B,B') and sal-Gal4/UAS-wg (C,C') or sal-Gal4/UAS-spi^S (D,D'). In all genotypes, embryos harbour filzkörpers elongation defects and reduced sized stigmatophores. Some variability in filzkörper defects is seen and illustrated in A',B',C',D', which show extreme phenotypes for each genotypes. Filzkörpers and stigmatophore defects are more pronounced when Wg and Spi^S expression is driven by sal-Gal4.