Objective: To investigate whether the division of the proximal genitofemoral nerve (GFN) in neonatal rats induces testicular undescent or ascent in adulthood.
Materials and methods: Neonatal Wistar King A rats underwent a unilateral proximal GFN transection on either the right or left side. At the age of 30 days, testicular descent was examined in all rats and the position of the testis recorded. The animals were allowed to develop further and the position of the testis re-examined at the age of 90-180 days, when the testes were removed and weighed. Sham-operated rats were used as controls.
Results: At the age of 30 days, four of the 46 (9%) operated rats showed a unilateral undescended testis on the operated side. At the age of 90-180 days, 43 rats were re-examined (three rats died before re-examination); 34 (79%) of these rats showed undescended testes on the operated side. The occurrence of cryptorchidism was significantly higher in the 90-180-day-old mature rats than in 30-day-old prepubertal rats (P<0.01). The mean (sd) weight of the undescended testes, at 2.36 (0.21) mg/g body weight, was significantly less than that of the contralateral scrotal testes, at 3.83 (0.23) mg/g; P<0.01) and of the control testes at the age of 90-180 days. In the sham-operated rats, all testes were located at the bottom of the scrotum at 30 days of age and no rats showed any testicular ascent thereafter.
Conclusions: The proximal division of the GFN in neonatal rats not only causes inguinoscrotal testicular maldescent but may also induce testicular ascent in adulthood. Testicular ascent may thus be caused by some intrauterine disorders of the GFN in patients with ascending testis.