Reversibility of ethylene oxide-induced testicular damage evaluated by the hemiorchiectomy method

In the present study, we tried to use the hemiorchiectomy method to examine a reversibility of the testicular damage induced by ethylene oxide (EtO). Wistar male rats were exposed to EtO at a concentration of 500 ppm, 6 hours a day, 3 days a week for 8 weeks. Thereafter we evaluated the reversibility after 13-week recovery period. From the result about a propriety of the hemiorchiecyomy method for recovery study, it was suggested that hemiorchiectomy did not affect remaining testis and epididymis after the recovery period and there was no laterality about the testicular damage just after the exposure period. Therefore we concluded that the hemiorchiectomy method could be used for recovery study for EtO-induced testicular damage. The reversibility was evaluated by comparing the damages of hemiorchiectomized testis just after the exposure period and those of remaining testis removed after the recovery period in the same rat. The result indicated that the reversibility of EtO-induced testicular damage may depend on a degree of damage just after the exposure.