Abstract: Objective To duplicate the animal model with coal burning fluorosis and to observe the influence of fluorosis on the ultrastructure changes of cerebral cortex.Methods Thirty-two SD rats were randomly divided into a control group and a high-fluoride exposed group.The exposed group were fed with the corn polluted in drying processes by burning coal containing high level of fluoride from the endemic fluorosis area to produce the animal model of fluorosis.After six months,the rats mated and their filial generation were observed at age of 30 days and fluoride contents in urine,bone,and brain of the offspring rats were detected by fluorine ion choose electrode.The ultrastructure of cerebral cortex of offspring rats were examined by H-7650 transmission electronic microscope.Results Compared with the offspring rats in the control group,the rats in high-fluoride exposed group had significantly increased fluoride contents in urine(8.52±1.61 vs 0.98±0.26 mg/L),bone(1874±544 vs 1 124±395 mg/kg),and brain(0.74±0.26 vs 0.36±0.12 mg/kg)(P < 0.05 or P < 0.01).But the weight of body mass and brain tissue,and the organosomatic index of the brain of the rats of the exposed group were significantly decreased(P < 0.15 or P < 0.01).The nerve cell nuclear envelope local absence,amalgamation of synaptic cleft,and nebulousness of mitochondria in presynaptic membrane and synaptic structure were observed in the high-fluoride exposed rats.Conclusion Chronic fluorosis could be induced in rats feeding with the corn polluted with high level of fluoride and result in increases of urinary fluoride,skeletal fluoride,and fluoride in brain tissue,decreases of the weight of body and brain tissue,and changes of ultrastructure of cerebral cortex in offspring rats with maternal fluoride exposure.