(A) E15.5 kidney sections were immunostained for Six2 (red), GM130 (Golgi; green) and DAPI (grey). The Golgi (white arrowheads) show a polarization to the distal end of nephron progenitors in wild type kidneys and this polarization is disrupted in Wnt11 mutants where they are localized closer to the ureteric branch tip (white outline). (B) Staining for GFP (green), GM130 (red), and cytokeratin (cyan) highlighting the normal polarization of Golgi within the nephron progenitor at E15.5. The letter ‘a’ marks the distance from the cell center to the foot of the cell (contact with tip) and ‘b’ marks the distance from the Golgi to the foot. (C) Ratio of the distances described in B) for wild type and mutant cells. Wild type cells show a smaller ratio indicating the Golgi lie farther from the ureteric tip than Wnt11 mutant cells, supporting their polarized nature and the loss in Wnt11 mutants. Three biological replicates and ~20 cells from each replicate were quantified. (D) E15.5 kidney sections immunostained for GFP (green), integrin a8 (Itga8; red) and cytokeratin (CK, cyan). Image shows the overlap of GFP +signal with Itga8 in cells close to the tip (white arrowhead), suggesting polarization of Itga8. (E) E15.5 kidney sections immunostained for Six2 (red), Itga8 (green), and cytokeratin (cyan). Arrowhead points to Itga8 polarization towards the ureteric branch tip in wild type kidneys, which is lost in Wnt11 mutants. (F) E15.5 wholemount immunostains for Six2 (red), desmin (Des; green), and cadherin 1 (Cdh1; blue) show the polarization of desmin foci (Des-foci) toward the ureteric branch tip which is disrupted in Wnt11 mutant kidneys. Since the desmin stain appears aster-like with wispy projections, the central focal point (foci) were identified for ease of distance quantitation. Foci were automatically located by Imaris imaging software as the most intense focal point of the desmin stain. (G) Quantitation of the percentage of desmin foci located greater than 5 μm from the ureteric tip in each genotype showing the greater dispersion from the tip in Wnt11 mutants. 385 foci from five control tips and 353 foci from four tips were analyzed. All error bars represent SEM. All significance values were determined by t-test. ns = p > 0.05, * = p < 0.05, ** = p < 0.01, *** = p < 0.001.