Figure 4
Enhanced or abrogated FGF10/FGFR2b signaling modulates embryonic SMG branching morphogenesis in vitro. A-B. Enhanced signaling. Paired E13 SMG primordia were cultured for 3 days in the absence (A) or presence (B) of 500 ng/ml FGF10 peptide supplementation. FGF10 induced a significant increase in branching compared to control (CONT). C-D. Abrogated signaling. Paired E13 SMG primordia were cultured for 3 days in 10 ng/ml IgG-Fc (C) or FGFR2b-Fc chimera (D). FGFR2b-Fc chimera treated explant exhibits a significant decrease in branching compared to IgG-Fc control. Bar, 30 μm. E. Comparison of mean Spooner ratios in E13 + 3 and E14 + 2 explants. Exogenous FGF10 peptide supplementation induced a significant 81% increase in E13 +3 explants [200 ng/ml (P < 0.01); 500 ng/ml (P < 0.001)] and a significant 46% increase in E 14 + 2 explants (P < 0.0001) compared to controls. FGFR2b-Fc chimera-mediated interruption of E13 + 3 and E 14 + 2 SMGs significantly reduced branching morphogenesis by 22% [E13 +3: 10 ng/ml (P < 0.01); E 14 + 2: 5 ng/ml (P > 0.0001); 10 ng/ml (P < 0.01)] compared to controls.