RESUMO
<p><b>OBJECTIVE</b>To study the changes of the contralateral testicular histology and germ cell apoptosis after unilateral testicular torsion (UTT) and to determine whether the contralateral testis is injured or not.</p><p><b>METHODS</b>Sixty SD male rats were divided into control group (12 rats) and experimental group(48 rats). The former underwent sham operation of the left testis under general anaesthesia. The latter underwent left testis torsion(720 degrees) for 6 h, and then 4 of them were sacrificed and the other 44 were subdivided into the torsed testis untwisted group (22 rats) and the torsed testis removal group (22 rats), 7-8 rats were sacrificed and both testes (twisted and untwisted) were removed 1 day, 1 week and 4 weeks after surgery. All testes underwent histological and germ cell apoptosis examination.</p><p><b>RESULTS</b>There were significant histological changes in the contralateral testis, and the germ cell apoptosis was increased greatly in the contralateral testis.</p><p><b>CONCLUSIONS</b>UTT can cause contralateral testicular injury, whose mechanism may be related to reperfusion, and torsed testis removal can prevent or reduce damage to the contralateral testis.</p>