Fig. 5. Altered cellular proliferation and gene expression in endodermal β-catenin LOF and GOF urethrae. All embryos were exposed to Tm on E10.5 and collected on E12.5. (A-A'') PHH3 staining showed reduced cell proliferation in Shh^Cre/esr;β-Cat^c/c UE (A'), and increased cell proliferation in proximal Shh^Cre/esr;β-Cat^loxEx3 UE (arrowheads, A''). UE is highlighted by white dashed lines. (B-C'') ³⁵S in situ hybridization on adjacent coronal sections. Shh expression is downregulated in both Shh^Cre/esr;β-Cat^c/c UE (B') and distal Shh^Cre/esr;β-Cat^loxEx3 UE (arrows, B''), but is maintained in the proximal Shh^Cre/esr;β-Cat^loxEx3 UE (arrowheads, B''). Bmp4 is normally expressed in distal mesenchyme (C), is downregulated in Shh^Cre/esr;β-Cat^c/c GT (C'), and is ectopically activated in the dUE of Shh^Cre/esr;β-Cat^loxEx3 GT (C'', arrows). Note the complementary expression pattern of Shh and Bmp4 in Shh^Cre/esr;β-Cat^loxEx3 dUE (B'',C''). Scale bars: 100 µm.