Objective    To determine the expressions of fibroblast growth factor receptors (FGFRs) during tibial cortical defect repair in mice.      Methods    Cortical defect was inflicted in C57BL/6J mice tibiae. The healing process was observed histologically on 7

14

and 21 d after injury with HE staining. Total RNA of the injury site was extracted in 3

7

14

and 21 d after injury (n=4 for each time point)

and then quantitative RT-PCR was employed to evaluate the mRNA temporal expression patterns of FGFRs and bone formation molecular markers during healing process.     Results    Consistent with prior reports

newly regenerated bone appeared in the marrow area at day 7 after injury. At day 21

a lamellar bone appeared at cortical bone region. The mRNA expression levels of Cbfa1 and osteopontin (OP) were up-regulated rapidly at early stage post-injury

Osteocalcin (OC) expression was also increased at later stage.FGFR1

2 expression peaking at day 3 after injury(FGFR1：2.09±0.25，FGFR2 1.82±0.15，P0.01);FGFR3 expression peaked at day 7(3.61±0.52，P0.01)

then decreased slightly at day 14 and was markedly up-regulated at day 21(P0.01).     Conclusion     Coincident with the increase of the bone markers

FGFR1

2

and 3 are significantly up-regulated at the early stage post-injury

and highly expressed during the healing process. FGFRs participate in the bone regeneration process after cortical defect.