Figure 2.

Several signaling gradients are integrated to specify the locations of two Br-expressing roof domains. A-C) Schematics of the signaling gradients that pattern the follicular epithelium are shown to the left. Simplified downstream signal-transduction networks are shown in the middle. The effect of these signals on Br expression during stage 10 is shown to the right; grey stripes indicate repression, blue indicates activation. Further details are provided in main text. Note that in (A), the light gray follicle cells in the schematized cross-section do not contribute to the columnar epithelium that surrounds the oocyte and produces the eggshell; instead, these cells become stretch and border cells. For more information on the developmental processes occurring between stages 6 and 10, see (Horne-Badovinac and Bilder, 2005). D) Due to the combined effect of all three signaling events, two patches of Br-expressing cells are formed (blue).