Fig. 4. sage is expressed specifically in the salivary gland and its later expression requires Fkh. (A) sage was detected in the salivary glands of wild-type embryos beginning at the placode stage through the end of embryogenesis. (B) sage expression after stage 12 was absent in fkh mutants. Compare staining indicated by arrows in left panels in the fkh heterozygotes, which also show lacZ expression from the TM3 Ubx-lacZ balancer chromosome (a-c), with staining indicated by arrows in the fkh mutants in the right panels (d-f). Salivary glands do not invaginate in fkh mutants (d-f).