Fig. 3. Wg, Hh and Egfr signalling are dispensable for posterior spiracle primordia specification. Expression at stage 11 of Cut (A,D,G,J), ems (B,E,H,K) and Sal (C,F,I,L) in wild-type (A-C) or wg (D-F), Egfr (G-I) and hh (J-L) mutant embryos. Arrows and circles indicate the sites of posterior spiracle formation. Cut and Sal expression is maintained in mutant contexts, while ems transcription is absent in wg and Egfr mutant embryos.