Accelerated osteoblast apoptosis and suppressed osteoblast proliferation following SCI. Sections through the distal femoral metaphysis were stained with cleaved caspase-3 (CC3) antibody to identify apoptotic osteoblasts in uninjured rats (top, panel a) and at 5 days post-injury (top, panel b). CC3 negative osteoblasts are seen in the uninjured rats (white arrows, panel a) and CC3 positive osteoblasts (red arrows, panel b) are seen at 5 days post-injury. Adjacent sections were stained with anti-BrdU antibody to identify proliferating osteoblasts in uninjured rats (bottom, panel c) and at 5 days post-injury (bottom, panel d). BrdU positive osteoblasts (white arrows, panel c) are seen only in the uninjured sections