Objectives: To confirm ROSs involvement in the meridians and indicate its conduction or transmission along the meridians.Methods: Male SD rats of 6 weeks were used.1 ml of DCFH-DA solution (10 mg in 1 ml dimethyl sulfoxide) was injected through the rat tail vein at different time of the day.30 minutes later, the rat frontal abdominal wall was incised from over iliac crest then along the midaxillary line on both sides up to the rib bone so that the interior wall could be exposed for fluorescent imaging.