Objective To observe the expression of mitochondrial fission protein locus Fis1 and ultrastructural changes in the renal cells of rats with chronic fluorosis,and to reveal the mechanism in mitochondrial damage of the renal cells.Methods Sixty SD rats were randomly divided into 3 groups according Objective To observe the expression of mitochondrial fission protein locus Fis1 and ultrastructural changes in the renal cells of rats with chronic fluorosis, and to reveal the mechanism in mitochondrial damage of the renal cells. Methods Sixty SD rats were randomly divided into 3 groups according to