Reduced canonical Wnt signaling in Pygo2 and Pygo1 / Pygo2 mutant embryos. E10.5 embryos, all with the BAT-gal transgene reporter of canonical Wnt signaling. (A) Pygo1
+/- embryos showed normal X-gal staining in the developing brain, pharyngeal pouches, otic vesicle, apical ectodermal ridges of the fore and hind limb buds, and in somites. (B) Pygo1
-/- embryos, with loss of both Pygo2 alleles, showed reduced but not absent BAT-gal reporter expression in many developing structures, including pharyngeal pouches, otic vesicle, and somites. (C) Pygo1
+/- embryo, with mutation of both Pygo1 alleles, but one wild-type Pygo2 allele, showed normal BAT-gal expression. (D) Double-homozygous mutant Pygo1
-/- embryos still showed some remaining BAT-gal expression, suggesting residual canonical Wnt signaling. Embryos in panels (A) and (B) were from the same litter and were processed in parallel, while embryos in (C) and (D) were from a separate litter, also processed in parallel, and were slightly more developmentally advanced. Original magnification (A, B) × 20; (C, D) × 16.