Fig. 7. ß_H segment 33 dominantly interferes with salivary gland development. (A) A stage 16 wild-type embryo expressing a nuclear UAS-LacZ marker and stained for ß-galactosidase protein to illustrate the normal position and morphology of the gland. (B) A stage 16 embryo co-expressing a nuclear UAS-LacZ marker and ßHPH+5-3 under the control of the fkh-Gal4 driver and stained for ß-galactosidase protein. Expression before invagination prevents complete internalization, with cells that remain on the surface being swept forwards to the head region during head involution. (C) Higher-magnification photomontage of the gland shown in B. Note how the posterior cells that first internalized resolutely assume their normal position (bracket 1), and that relatively few cells extend to the location of the cells that do not internalize (bracket 2). (D) Projected confocal series of a salivary gland from a stage 13 embryo expressing ßHPH+5-3 under the control of the fkh-Gal4 driver. The embryo was stained for ßHPH+5-3 (left image, red in merged center panel) using the mAb 9E10 and for the lumenal marker DMoesin (right image, green in merged center panel). For clarity in the projection, the 9E10-staining region was used as a guide to select DMoesin staining that is in the gland cells. DMoesin staining is actually very widespread (inset shows the uncropped outermost section from the series; see also Fig. 3L). Bracket indicates the continuity of the lumen revealed by DMoesin staining.