Fig. 7. Shh and BMP2 induced cell proliferation in the anterior palatal mesenchyme determined by BudU labeling. (A,B) BMP2-soaked beads induced cell proliferation in E13.5 palatal mesenchyme 8 hours after bead implantation, in both wild-type (A) and Msx1mutant tissues (B). Note that BrdU-labeled cells asymmetrically localized closer to the MEE (arrows). (C,D) BSA-soaked control beads failed to induce cell proliferation in the palatal mesenchyme of E13.5 wild-type (C) and Msx1 mutant embryos (D). (E,F,H) Shh-soaked beads induced cell proliferation (arrows) around the beads in E13.5 wild-type (E) and Msx1^–/– palatal mesenchyme (F) 24 hours after bead implantation. However, Shh-soaked beads failed to induce cell proliferation in both wild-type (data not shown) and Msx1^–/– palatal mesenchyme (H) 8 hours after implantation. (G) A bead loaded with both Shh and Noggin proteins failed to induce cell proliferation 24 hours after bead implantation. (I) Beads soaked with an anti-Shh antibody inhibited cell proliferation in palatal tissue explants containing both the epithelium and mesenchyme of E13.5 wild-type embryo. (J) A BSA-soaked control bead did not affect cell proliferation (arrow) when implanted into E13.5 wild-type palatal tissue explants containing both the epithelium and mesenchyme. (K) Cell proliferation (arrows) was induced in E13.5 wild-type palatal tissue explants containing both the epithelium and mesenchyme 24 hours after implantation of a bead soaked with both an anti-Shh antibody and BMP2 protein. In all panels, the MEE aspect is towards the left. All palatal tissues used in this figure were from the anterior region of palatal shelves. b, bead.