In situ hybridization of drm mRNA to embryos at late cellular blastoderm, early germ band extension and full germ band extended stages: (A, B, C) OreR; (D, E, F) ftz9H34 mutant; (G, H, I) ftz-f119 mutant; and (J, K, L) UAS-myc-ftz/ NGT40 embryos. drm is expressed in seven strong primary stripes, with a set of weaker secondary stripes becoming stronger as development proceeds. In ftz or in ftz-f1 mutant embryos, half of the stripes seen in the wild type are missing, while ectopic Ftz expression alters the pattern of drm stripes.