Fig. 7

Representative histological samples of fracture calluses at days 14 and 42 after fracture (HE and Masson trichrome stain, magnification, × 40). (Top line) HE stain. (Bottom line) Masson trichrome stain. (Left panel) 14 days after fracture. (Right panel) 42 days after fracture. Callus samples in A1, A2, D1, and D2 were from mice that received BMSC injection at 7 days after fracture. B1, B2, E1, and E2 from mice that received AMD3100 and BMSC injection at 7 days after fracture. C1, C2, F1, and F2 from the control group that received saline injection at 7 days after fracture. More bony calluses were formed in the MSC group than in the AMD group and control group at 14 days after fracture. At 42 days after fracture, bone remodeling had been basically completed in the MSC group, but in the AMD group and control group is still in the shaping process. Black arrows indicate the bone fracture lines