RESUMEN
BACKGROUND: Long-term radioactive ray accumulation leads to surrounding tissues fibrosis accompanied by limitation of mouth-opening, which seriously affects life quality of tumor patients. OBJECTIVE: To observe pathological change of soft tissues in rats with radiation masseter injury and the level of transforming growth factor β1 (TGF-β1) mRNA expression in vivo.METHODS: A total of 30 Wistar rats were randomly divided into control group (n=10) and radiated group (n=20). Radiated group were radiated with linear accelerator at a dose of 40 Gy. The pathological changes of vessels were observed under light microscope and electron microscope and expression of TGF-β1 was detected by RT-PCR. RESULTS AND CONCLUSION: The microvessel density of radiated group was obviously decreased than that of the control group (P < 0.01), but the mRNA expression of was higher than that in the control group (P < 0.01). It suggests that radiated injury can induce fibrosis to repair the radiated injury.