FIG. 4.

Notch expression in the “T” prefigures primordium fates. Stage 10 egg chambers express Notch (A, C, in green), Broad (B, D, in green), or rhomboid-lacZ (red). Anterior is to the left. A yellow arrow labels the dorsal midline. (A) At mid stage 10, Notch expression is high in a dorsal anterior “T,” including the centripetal cells, dorsal midline cells, and future floor cells. The floor cells, however, do not yet express the rhomboid-lacZ reporter. (B) In cells expressing high Notch, Broad is degraded. (C) At late stage 10, Notch expression diminishes as the floor-cell marker appears. (D) Broad is expressed at high levels in roof cells, moderate levels in main-body follicle cells, and not at all in cells of the “T.” Modified from Ward et al.⁵¹