<p>(A) Coronal sections of control, <i>Brca1</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> and <i>Brca1</i><sup><i>-/-</i></sup>:<i>p53</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> frontal bone primordia at E12.5 were double-labeled with RUNX2 (red) and BrdU (green). Broken line describes the osteogenic lineage cell population. Right charts show quantification of the ratio of BrdU-positive cells over RUNX2-positive cells. Scale bar = 50μm. (B) Immunostaining for RUNX2 and TUNEL assay of sections from control, <i>Brca1</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> and <i>Brca1</i><sup><i>-/-</i></sup>:<i>p53</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> embryos at E12.5. Broken line describes the osteogenic lineage cell population. White arrows indicate TUNEL-positive cells. Yellow color represents the non-specific signal from red blood cells. Right chart shows quantification of the percentage of TUNEL-positive cells in the frontal bone primordium. (C) Immunostaining for γ-H2AX and Cleaved Caspase-3 and/or p-Chk2 of sections from control, <i>Brca1</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> and <i>Brca1</i><sup><i>-/-</i></sup>:<i>p53</i><sup><i>-/-</i></sup>:<i>Wnt1-Cre</i> embryos at E12.5. Broken line describes the osteogenic lineage cell population. White arrows indicate double-positive cells for γ-H2AX/Cleaved Caspase-3 and/or γ-H2AX/p-Chk2. Right chart shows quantification of the percentage of γ-H2AX, Cleaved Caspase-3 and p-Chk2 positive cells in the frontal bone primordium. Scale bar = 100μm. Data in A, B and C are represented as mean ±SD, n = 3 in each group. *P<0.05. N.S., not significant.</p
