Fig. 3

Osteotomy ‘defect’ site (black arrows) in a rat femur at 5 weeks post-trauma (wpt). A Hematoxylin and eosin (H&E) stained section of femur in the osteotomy group (OST). The callus of new bone growth (blue arrow) and fibrous connective tissue (CT) (12.5x). B Higher magnification of image A (100x). C Section of femur in polytrauma control (PT-C) group. The callus consists of new bone growth (blue arrow) and immature connective tissue (CT). Note the island of woven bone and bone marrow (red arrow) and focus of inflammation (yellow arrow) (12.5x). D Higher magnification of C (100x). E Higher magnification Figure C (400x). The focus of inflammation consists of multinucleated giant cells (black arrow), macrophages (red arrow), plasma cells (green arrow), lymphocytes (yellow arrow), and hemosiderin-laden macrophages (blue arrow) (chronic hemorrhage). F Section of femur in polytrauma + anti-HMGB1 antibody (PT-Ab HMGB1) group. The majority of the callus consists of new bone growth (blue arrow) with cartilage formation (yellow arrow). G Higher magnification of Figure J (100x). Compare the immature, woven bone (WB) in the callus to the mature, lamellar bone of the femur (LB). Graphical representation of the presence of H hemosiderin-laden macrophages; I osteoblasts; and J osteoclasts within the defect at 5 wpt in OST, PT-C, and PT-Ab HMGB1 rats (n = 4–8/group). The scoring key for hemosiderin-laden macrophages, osteoblast and osteoclasts is mentioned in the material and methods section