Fig. 3. Drosophila E-cadherin is expressed in germ cells and SGPs during gonad coalescence. Anterior is leftwards. All embryos are stained for Drosophila E-cadherin. (A-D) Expression of E-cadherin in stage 12 (A), stage 13 (B), stage 14 (C) and stage 17 (D) gonads. (C,D) Male embryos. SGPs and msSGPs (large arrow in C) are labeled with anti-EYA in A-C. Gonad boundaries (SGPs) indicated with broken lines. E-cadherin expression in the SGPs appears between stages 12 (A) and 13 (B), correlating with the onset of coalescence. E-cadherin expression is maintained in the gonad throughout embryogenesis and is increased at the anterior of the gonad during late stages (a, anterior; D). See text for further discussion of symbols. (E) Stage 15 embryo double labeled for E-cadherin and Armadillo/ß-catenin. Note the extensive co-localization of these proteins. (F) Stage 15 male. UAS-mCD8-GFP expressed in germ cells (nos-Gal4) co-localizes with E-cadherin, indicated by yellow, except in regions of germ cell-germ cell contact (black arrowhead). msSGPs (arrow) also exhibit E-cadherin expression. Higher magnification view of two germ cells co-expressing mCD8-GFP and E-cadherin on their cell surfaces. There is also a region of E-cadherin alone between these two cells that is probably an ensheathing SGP. (G) Stage 11. E-cadherin is present at the surface of migrating germ cells (asterisks). Germ cells were identified by co-expression of mCD8-GFP crossed to nanos-Gal4 (not shown). (H) Stage 15. mCD8-GFP expressed in the mesoderm (24B-Gal4) co-localizes with E-cadherin. (I) Stage 15 agametic (osk) embryo, EYA labels SGPs. Note that E-cadherin is expressed even though no germ cells are present. (J) Stage 14 eya^Cli-IID mutant. Germ cells labeled with Vasa clearly express E-cadherin. Surrounding ZFH-1-positive cells, potentially SGPs or other mesodermal cells, do not display E-cadherin staining. t, trachea; hg, hindgut. Scale bar in A: 10 µm.