Fig. 6. Analyses of cell proliferation and cell apoptosis in wild-type (WT) and Mn1^-/- mutant embryos at E15.5. (A-C) Cell proliferation in palatal mesenchyme detected using immunohistochemical staining of the Ki67 protein. In comparison with wild-type embryos (A), cell proliferation in the middle palatal region in Mn1^-/- mutant embryos (B) was greatly reduced. Error bars in C represent standard deviation and the asterisk indicates a significant difference (P<0.01) between the wild-type and mutant samples of mesenchyme and epithelium. (D,E) TUNEL assays of mid-palatal sections of E15.5 palatal shelves of wild-type (D) and Mn1^-/- mutant (E) embryos showed increased cell apoptosis in the palatal mesenchyme in the mutant. Small arrows indicate highly TUNEL-positive palatal mesenchymal cells and arrowheads indicate highly TUNEL-positive palatal epithelial cells.