GFP⁺ PGCs in the gonadal ridge. (A) GFP (green) and AP (red) staining in TG1 immunopurified gonadal ridge PGCs (E10.5). (B) GFP (green; Bi) and TG1 (red, membrane staining; Bii) of PGCs from E11.5 gonads; in panel Biii the images are merged. (C-E) Comparison of GFP fluorescence of gonadal ridge from construct 3 (panel C, left image) and 1 (panel C, right image) lines and of dissociated cells (panels D [construct 3] and E [construct 1]) at E11.5. Panels Di and Ei show GFP fluorescence, and panels Dii and Eii show TG1 fluorescence. Results with construct 2 are essentially identical to those with construct 3. All the construct 1 lines show very weak fluorescence. No nonspecific fluorescence is detected with nontransgenic embryos. Original magnifications, × 400 (A-B, D-E) and × 40 (C).