Fig. 3. Ctnnb1-positive cells are more likely than Ctnnb1-negative cells to become UGS basal epithelium.

Male Shh^creERT2/+;Ctnnb1^tm2Kem/+;R26R⁺ (control;R26R) and Shh^creERT2/+;Ctnnb1^{tm2Kem/tm2Kem};R26R⁺ (Ctnnb1^iLOF;R26R) embryos were exposed to tamoxifen and progesterone as described. (A–B) E18.5 UGSs were stained to visualize LacZ activity, embedded in paraffin, sectioned and immunofluorescently labeled to detect the cell proliferation marker Ki67 and KRT14. Brightfield LacZ staining images were captured, inverted, pseudocolored yellow and merged with fluorescent images. Nuclei were stained with DAPI. Staining patterns represent at least three UGSs per genotype. Arrowheads indicate prostatic buds. (C) The LacZ⁺ cell percentage of KRT14⁺ cells and (D) the Ki67⁺ cell percentage of LacZ⁺;KRT14⁺ cells are mean ± SE of three independent samples per group from at least three litters. Asterisks indicate significant differences from controls (p < 0.05).