Fig. 3

a Upon injury the cytokine expression changes in the periosteum directly adjacent to the bone injury: C = uninjured control, IB = injured bone 60 h after injury. HIF1a, HMOX1, and PDGF, three factors highly relevant for revascularization are significantly upregulated in the periosteum upon injury. b Tissues involved in bone healing, periosteum, haematoma, and bone marrow were investigated under normal and delayed healing conditions. The cytokine expression and also the cellular composition in all compartments was significantly altered under mechanically induced delayed healing conditions. For detailed information please refer to: (Schmidt-Bleek et al. 2012a; Schmidt-Bleek et al. 2012b). For statistical analyses of data, medians were calculated for each group per time point. Statistical comparisons between the groups were performed using the Mann–Whitney U-test (SPSS 22; SPSS, Inc., Chicago, IL)