Fig. 7. Activated Wnt/ß-catenin signaling in renal vesicle progenitor cells in mice is sufficient to induce mesenchymal induction markers in the absence of Wnt4. (A-P) Whole-mount in situ hybridization at E12.5. (A,E,I,M) Whole-mount in situ hybridization of HoxB7 and (B-D,F-H,J-L,N-P) the mesenchymal induction markers (Fgf8, Pax8 and Lhx1) to E12.5 embryonic kidneys. Although Wnt4 mutant kidneys express Fgf8 (F), they do not express Pax8 and Lhx1 in the mesenchyme (G,H). In Wnt4 mutants, Pax8 and Lhx1 are expressed only in the collecting duct (G,H). Six2TGC-mediated activation of Wnt/ß-catenin pathway causes ectopic expression of the mesenchymal induction markers in both Wnt4 heterozygotes (J,K,L) and mutants (N,O,P).