The effect of orchidectomy on gubernacular outgrowth and regression in the dog

To test whether the outgrowth and regression of the gubernaculum testis and consequently testicular descent are testis dependent, unilateral and bilateral orchidectomies were performed on foetal dogs at 49 days post coitum (p.c.), and on newborns at day 0 and day 3 after birth. Prior to these experiments the vascularisation of the testis, epididymis and gubernaculum had been studied to develop a method of orchidectomy, in which the vascularisation of the gubernaculum and epididymis was minimally damaged. After bilateral orchidectomy at 49 days p.c., outgrowth of the gubernaculum stopped completely, and the epididymis remained in its original abdominal position. After bilateral orchidectomy at birth, the descent of the remaining epididymis from an intra-abdominal to an extra-abdominal position was retarded, due to retarded regression of the gubernaculum. Bilateral orchidectomy 3 days after birth resulted in a slightly retarded gubernacular regression. After unilateral orchidectomies the effects were similar but less pronounced. It was concluded that the testis induces and maintains the outgrowth and initiates regression of the gubernaculum, thereby regulating the process of testicular descent. However, once the regression had started, it appeared to proceed more or less autonomously.