DE-cadherin anchoring SSCs in their niches. Germaria labeled for LacZ (red), Hts (green), and nuclei (blue). Marked lacZ⁻ SSC clones or follicle cell clones are outlined. (A) A germarium carrying a wild-type SSC clone that is evident by the presence of LacZ-negative follicle cells. (B) A 3-week-old marked lacZ⁻ wild-type SSC clone showing that all follicle cells are LacZ-negative. In this germarium, the lacZ⁺ SSC was lost and/or replaced by a marked lacZ⁻ SSC. (C) A 3-week-old germarium carrying only marked lacZ⁻ follicle cells from a shg¹⁰⁴⁶⁹ SSC clone. This has also resulted from the loss and/or replacement of a lacZ⁺ wild-type SSC by a marked lacZ⁻ SSC. (D) A germarium carrying no marked lacZ⁻ shg¹⁰⁴⁶⁹ SSCs with marked lacZ⁻ follicle cell patches on egg chambers (E) 3 weeks after clone induction. (F) A 1-week- old shg^R69 SSC clone. (G) A germarium with no shg^R69 SSCs but having marked lacZ⁻ follicle cell patches on egg chambers (H) 2 weeks after clone induction. The marked mutant follicle cells in E and H were identified by loss of expression of cytoplasmic LacZ and increased expression of nuclear LacZ because shg¹⁰⁴⁶⁹ and shg^R69 still have a nuclear LacZ gene inserted in the locus capable of expressing it in late follicle cells. All of the germaria are shown at the same scale. (Bar in A represents 10 μm.)

The requirement of DE-cadherin-mediated cell adhesion for SSC maintenance before adulthood. Ovaries of the females that developed from heat-shock-treated late third-instar larvae labeled for LacZ (red), Hts (green), and nuclei (blue). (A) A wild-type germarium showing a marked lacZ⁻ SSC clone (outlined). (B) A germarium showing a marked lacZ⁻ mutant shg¹⁰⁴⁶⁹ SSC clone (outlined). (C) A germarium showing no mutant shg^R69 clones with a lacZ⁻ mutant follicle clone on late egg chambers (D). All of the micrographs are shown at the same scale. (Bar in A represents 10 μm.)

DE-cadherin and Arm in the interface between SSCs and IGS cells. (A) A cross-section diagram of a Drosophila germarium. (B) A confocal section of a germarium containing a marked lacZ⁺ SSC labeled for LacZ (red), Fas3 (green), and nuclei (blue). One marked lacZ⁺ SSC (arrow) is evident in the middle of germarium by its low Fas3 expression and the production of LacZ-positive follicle cells (one indicated by arrowhead). (C) A germarium containing two marked lacZ⁺ IGS cells labeled for LacZ (red), Fas3 (green), and nuclei (blue). Two lacZ⁺ IGS cells (arrows) with low levels of Fas3 expression are apparent, but LacZ-positive follicle cells are not present in the ovariole. (D and E) A germarium carrying a marked lacZ⁺ SSC labeled for DE-cadherin (green), LacZ (red), and nuclei (blue). (D) The SSC is identified by its location in the middle of the germarium and capacity to generate LacZ-positive follicle cells (one indicated by arrowhead). (E) The enlarged area (dotted rectangle shown in D) showing the existence of DE-cadherin-positive foci (arrowheads) between a marked lacZ⁺ SSC and neighboring IGS cells. (F and G) A germarium carrying a marked lacZ⁺ SSC labeled for Arm (green), LacZ (red), and nuclei (blue). (F) The SSC is identified by its location in the middle of the germarium and capacity to generate LacZ-positive follicle cells (one indicated by arrowhead). (G) The enlarged area (dotted rectangle shown in F) showing the existence of Arm-positive foci (arrowheads) between a marked SSC and neighboring IGS cells. CB, cystoblast; CPC, cap cell; DCs, developing cysts; FC, follicle cell; FS, fusome; SS = spectrosomes; TF = terminal filament cell. (Bars in B and C represent 10 μm.)

Diminished accumulation of DE-cadherin and Arm in the junctions between germ cells and mutant shg follicle cells after removal of a functional shg gene from SSCs. (A and B) One-week-old germaria labeled for LacZ (red), DE-cadherin (green), and nuclei (blue). Both panels illustrate the interface (dotted line) between lacZ⁻ mutant shg^R69 follicle cells and germ cells, and the interface (solid line) between lacZ⁺ wild-type follicle cells and germ cells. The removal of DE-cadherin from follicle cells can disrupt its accumulation in the interface between follicle cells and germ cells. (C) One-week-old germarium labeled for LacZ (red), Arm (green), and nuclei (blue). The dotted line indicates the interface between lacZ⁻ mutant shg^R69 follicle cells and germ cells, and the solid line indicates the interface between lacZ⁺ wild-type follicle cells and germ cells. The removal of DE-cadherin from follicle cells disrupts Arm accumulation in the interface between follicle cells and germ cells. (D) Part of an ovariole labeled for LacZ (red), Arm (green), and nuclei (blue) showing a patch of lacZ⁻ shg^R69 mutant follicles (outlined) in the region between a germarium and a stage-2 egg chamber. All of the micrographs are shown at the same scale. (Bar in A represents 6.7 μm.)