Fig. 1. wg signaling regulates follicle cell production or differentiation in the Drosophila ovary. (A) Cross-sectional diagram of a Drosophila germarium. Two or three SSCs, follicle cell progenitors and differentiated follicle cells are located in regions 2A, 2B and 3, respectively. The micrographs in B-E represent one confocal cross section of the germarium or ovariole. (B) A wild-type germarium labeled for Wg (red) and nuclei (blue). Terminal filament and cap cells in the germarium express Wg proteins (cap cells indicated by arrowheads). (C) A wild-type germarium labeled for Hts (red) and nuclei (blue) showing 16-cell cysts (outlined). (D) A mutant wg^ts germarium labeled for Hts (red) and nuclei (blue) showing accumulation of extra 16-cell cysts (outlined). (E) A mutant wg^ts germarium labeled for Hts (red) and nuclei (blue) showing ongoing encapsulation of two cysts (outlined and indicated by arrows) into an egg chamber. All the germaria are shown at the same scale. Scale bar in B: 10 µm. CB, cystoblast; CPC, cap cell; DCs, developing cysts; FC, follicle cell; FS, fusome; GSCs, germline stem cells; IGS, inner germarial sheath cell; SS, spectrosomes; SSCs, somatic stem cells; TF, terminal filament cell.