Fig. 3. SMGs treated with rFGFR2b for 44 hours show decreased epithelial cell proliferation (A-C) and increased mesenchyme apoptosis (D-F). Images are maximum projections of optical sections through an entire gland. (A) Control gland shows BrdU labeling (green and yellow) concentrated on the epithelial buds and at the periphery of the mesenchyme. FGFR2 (red) is present mainly on the epithelial buds and on some mesenchyme cells. Scale bar: 200 µm. (B) rFGFR2 treatment results in less BrdU labeling on the epithelial buds. (C) The fluorescent BrdU staining was quantitated (see Materials and methods), and the total fluorescent pixels were expressed as a ratio of the area of the gland. At least five glands/condition were used for quantitation, and the experiments were repeated three times (ANOVA, ^**P<0.001). (D) Apoptosis of mesenchyme cells at the edges and on the surface of the glands in culture was detected with TUNEL staining (red); epithelium was stained with FITC-peanut lectin (green). (E) rFGFR2b treatment increases apoptosis in the mesenchyme, although no epithelial apoptosis is observed. (F) The fluorescent TUNEL staining was quantitated as described above (ANOVA, ^**P<0.001).