Pubertal genitofemoral nerve division induces testicular ascent in adult rats

BACKGROUND/PURPOSE: Ascending testes, which normally are located at the bottom of the scrotum in early infancy and later ascend back out of the scrotum, have been reported by several investigators. However, little is known about the effect of the division of the genitofemoral nerve (GFN) on testicular ascent as boys grow. The purpose of this study is to investigate whether the division of the proximal genitofemoral nerve in prepubertal rats induces testicular ascent in adulthood. METHODS: Thirty-day-old Wistar King A Rats (n = 27) underwent a unilateral proximal GFN transection on either the right or left side. At 150 days of age, the rats were killed, and their testicular position was examined. The length of the processus vaginalis was measured, and the testes were removed and weighed. Sham-operated rats were used as controls (n = 10). Student's t and the chi2 test were used for the statistical analysis. RESULTS: At 150 days of age, 21 of the 27 operated rats (77.8%) showed unilateral testicular ascent on the operated side. All testes were located at the bottom of the scrotum in sham-operated control rats (20 testes). Both the length of the processus vaginalis and the testicular weight were decreased significantly more on the operated side than in the sham-operated rats. CONCLUSIONS: These findings suggest that the proximal division of the genitofemoral nerve in prepubertal rats may induce a relative ascent of the testis by preventing the growth of the processus vaginalis in adulthood. In patients with such ascending testes, an abnormal development or accidental trauma of the genitofemoral nerve may be involved in testicular ascent.