Fig. 8. Repression of Tsh is required for wing pouch formation. (A) scalloped^Gal4 UAS-Tsh wing disc labeled to visualize Wg (red), Hth (blue) and Tsh (green). Note the absence of the wing pouch and the lack of the DV boundary stripe and rings of Wg expression. The folding of the discs makes it difficult to get all nuclei in the same horizontal optical section. The optical cross section at right shows that Hth was expressed in all nuclei, indicating that wing pouch specification has been blocked (B) dpp^Gal4 UAS-Tsh wing disc labeled to visualize Vg (red), Nub (blue) and Tsh (green). Nub was partially repressed in the dorsal and ventral compartments. We also noted stronger repression in a part of the dorsal territory. The basis for this difference is not clear, but we noted weak Tsh expression in much of the stronger repression domain. Perhaps this reflects intrusion of tissue from the hinge region due to ectopic Tsh expression.