Additional Supporting Information may be found in the online version of this article.

DVDY_22501_sm_SuppInfoFigS1.tif4312KSupp. Fig. S1. Comparison of apoptosis in embryonic day (E) 10.5–E11.5 control and Fgfr1Mes−/−Fgfr2IIIc−/− kidneys. A,C: TUNEL (terminal deoxynucleotidyl transferase–mediated deoxyuridinetriphosphate nick end-labeling) staining at E10.5 shows low levels of apoptosis (green dots) in control (A) and Fgfr1Mes−/−Fgfr2IIIc−/− (C) metanephric mesenchyme (dotted line) and ureteric buds (arrowheads). B,D: At E11.5 comparable levels of apoptosis are apparent in both control (B) and Fgfr1Mes−/−Fgfr2IIIc−/− (D) metanephric mesenchyme (dotted line). Several apoptotic cells were present in Fgfr1Mes−/−Fgfr2IIIc−/− ureteric buds, in contrast to controls. Scale bar = 50 μm.
DVDY_22501_sm_SuppInfoFigS2.tif2252KSupp. Fig. S2. Comparison of Fgfr2IIIb expression in control and Fgfr2IIIc−/− kidneys at embryonic day (E) 12.5. A: Sections from E12.5 kidneys stained by whole-mount in situ hybridization reveals moderate Fgfr2IIIb signal in control stromal cells around the positive main ureteric trunk (arrowhead) and light signal in the cortical nephrogenic zone near the ureteric tips (arrow). B: Fgfr2IIIc−/− kidneys reveal a similar, albeit stronger Fgfr2IIIb staining pattern around the epithelial ureteric trunk (arrowheads) and nephrogenic zone (arrow). Original magnification: ×200.
DVDY_22501_sm_SuppInfoFigS3.tif2088KSupp. Fig. S3. Eya1 and Foxd1 expression in embryonic day (E) 12.5 control and Fgfr1Mes−/−Fgfr2IIIc−/− kidney tissues. A,B: In situ hybridization shows Eya1 expression in nephrogenic zone in controls (A, arrowheads) and in mutant remnant mesenchymal tissues (B, arrowheads). C,D: In situ hybridization for Foxd1 demonstrates signal in cortical stroma in controls (C, arrowhead), but no expression in remnant mutant kidney tissues (D, arrowhead). ×200 magnification.
DVDY_22501_SuppInfoMovieS1.avi14202KSupp. Movie S1. Control embryonic day (E) 10.5 metanephric mesenchyme 3D reconstruction. Blue, nephric duct; green, metanephric mesenchyme; pink, ureteric bud.
DVDY_22501_SuppInfoMovieS2.avi15184KSupp. Movie S2. Fgfr1Mes−/−Fgfr2IIIc−/− E10.5 metanephric mesenchyme three-dimensional (3D) reconstruction. Blue, nephric duct; green, metanephric mesenchyme; pink, ureteric bud.

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