We also examined BAT-gal reporter expression in more detail in the developing urogenital system of Pygo mutants. The results suggested that the Pygo2 gene is required for canonical Wnt signaling in the nephric duct. Both Pygo2 null and Pygo1/Pygo2 double-null E10.5 embryos showed an absence of reporter expression in the nephric duct, while control littermates showed strong expression (Figure 6A–C). In Pygo1/Pygo2 double-null mutants, the nephric duct did form, however, and give rise to the ureteric bud outgrowth, which showed reduced but not absent BAT-gal reporter expression (Figure 6A–C).