Abstract: Objective To study the relationship between the expression of vmientin in sustentacular cells and the quan tity of sperm in rats exposed to manganese.Methods Forty-eightmale rats were randomly divided into 6 groups.The rats in treatment group were exposed to MnCl₂ at 15 mg/kg and 30 mg/kg for 4 and 6 weeks and therats in blank control group were injected with normal saline.The testis and epididym is were collected for the detection of vmientin expression in susten tacular cells with mimunoh isto chemicalme thod and the quantity of sperm was determ ined.Results The vmientin-positive cell rates were 30.55±2.33%,9.01±2.27%and 7.62±1.08%,2.33±0.63%,and the quantities of sperm were 0.53±0.11,0.47±0.06 and 0.26±0.07,0.23?0.04×10⁷/mL for the rats in 15 mg/kg and 30 mg/kg of 4 and 6 weeks expo sure groups,respectively.Compared with the blank control,the vmientin-positive-cell rate and the quantity of sperm in all manganese exposure groups decreased significantly(P < 0.01) with dose-and time-effect manner.There existed a positive correlation between the quantity of sperm and the the vmientin-positive-cell rate(r=0.895,P < 0.01).Conclusion The expression of vmientin in sustentacular cells decreases with excessive manganese leading to the decrease of sperm quantity, which may be one of the most important molecularm echanisms of sperma to genic disturbance.