The role of a non-androgenic testicular factor in the process of testicular descent in the dog

Previous experiments with orchidectomized foetal and neonatal dogs have shown that the testis can induce outgrowth as well as regression of the gubernaculum testis and consequently, govern both the first and second phases of testicular descent. The aim of this study was to test whether it was possible to prevent the effects of orchidectomy on the gubernacular reaction and on epididymal migration by the administration of testosterone or by auto-transplantation of testicular tissue. In dogs, orchidectomized during foetal life and supplemented with testosterone, gubernacular regression was not completely prevented, and some descent of the remaining epididymis was obvious. However, the descent was less than in normal, intact animals. In dogs orchidectomized neonatally and supplemented with testosterone, the gubernacula showed normal regression and an almost normal descent of the epididymis. In dogs orchidectomized neonatally and supplemented with an auto-transplant of testicular tissue into to the scrotum, normal gubernacular development and normal epididymal descent were observed. We concluded that together with an unidentified non-androgenic testicular factor, testosterone from the testis appears to play a role in the outgrowth phase of the gubernaculum and consequently, in the first phase of testicular descent. In addition, testosterone was found to induce gubernacular regression in the second phase of testicular descent.