Expression of Tc-hh in wildtype and Tc-kni RNAi embryos. The antennal Tc-hh stripe (marked by white arrowhead in wildtype panels A, C, E, G) is missing in all Tc-kni RNA embryos (panels B, D, F, H). The mandibular Tc-hh stripe (marked by black arrow in panels A, C, E, G) is broken (panels B, D) and later missing (panels F, H) in Tc-kni RNAi embryos. Tc-hh expression in the intercalary segment (black asterisks in panels E, F) appears at a variable time point in mid-elongation stage embryos in both wildtype and Tc-kni RNAi embryos. Tc-hh expression associated with structures at the base of the antenna is evident in late Tc-kni RNAi embryos (red arrow in panels F, H). A black arrowhead in all panels marks the maxillary Tc-hh stripe. Ventral views, and anterior towards the top, in all panels.