Abstract: Abstract：　Objective　 To establish an in vitro mechanical stimulation model of cranial base synchondrosis chondrocytes. To explore the effects of cyclic tensile strain (CTS) with different frequencies and elongation rates on cranial base synchondrosis chondrocytes. Methods　 Cyclic tensil stress was imposed to the second passage of cranial base synchondrosis chondrocytes by Flexcell Strain Unit-5000T. The elongation rates were 5% or 10%. The frequencies applied were 0.3Hz, 0.5Hz or 1Hz. After mechanical loading, total RNA of the cells harvested from six-well BioFlex was extracted. Real-time quantitative RT-PCR was performed to quantify the mRNA levels of type Ⅱ collagen and Sox9. Results　 Compared with the control group, the mRNA expression of Col-Ⅱ and Sox9 increased significantly(P＜0.05) when elongation rate was 10% and frequency was 0.5Hz or 1Hz. Conclusions　 Cyclic tensil stress with appropriate frequency and elongation rate can promote the synthesis of extracellular matrix of cranial base synchondrosis in vitro.

Key words: Key words：　Cyclic Tensil Stress, Cranial Base Synchondrosis, Type Ⅱ Collagen, Sox9