Fig. 6. FGF-induced morphogenesis is a result of localized proliferation. (A) Individual FGFs, FGF1 (200 ng/ml), FGF2 (100 ng/ml), FGF4 (100 ng/ml), FGF7 (100 ng/ml) and FGF10 (500 ng/ml), stimulate proliferation of epithelial buds by 8 hours, before any morphogenesis has occurred. BMP4 (100 ng/ml) and BMP7 (100 ng/ml) did not stimulate epithelial proliferation above control levels. Scale bar: 50 µm. BrdU was detected with a Cy3-labeled antibody, the nuclei were stained with SYBR-green, and fluorescence was quantitated using MetaMorph software and expressed as the ratio of BrdU:SYBR-green pixels. At least five glands/condition were used for quantitation, and the experiments were repeated twice with similar results. (B) FGFs induce localized proliferation resulting in distinct morphologies by 44 hours. FGF1 and FGF10 stimulate proliferation at the tips of the ducts. FGF2 and FGF7 stimulate proliferation over the entire buds, and FGF7 also induces duct proliferation. BrdU was detected with a Cy3-labeled antibody, and nuclei were stained with SYBR-green. Scale bar: 100 µm.