Morphogenesis of the gubernaculum testis in Sprague-Dawley rat. Preliminary report

The morphology of testicular descent in the Sprague-Dawley rat from day 14 of gestation to newborn was studied; the purpose was to analyse the anatomy and related observations made with light and scanning microscopy. Adult female rats were mated during estrus. The presence of spermatozoa in vaginal smears was taken to indicate day 0 of gestation. Animals were kept in a controlled 12-hour light-darkness cycle; food and water were provided ad libitum. At day 14 genital ducts are similar in both sexes. At day 15 and 16 the gubernaculum testis is seen as a mesenchymal cord that extends from mesonephros to the pelvic floor. At day 17 near the enlarged caudal end of gubernaculum, evagination of the abdominal cavity begins forming the peritoneo-vaginal process. The testis ligament as well as the gubernaculum testis attaching to the epididymis at different locations have no direct relation between themselves as such. During day 18, testis rotates on its own longitudinal axis in a ventral-lateral direction. This movement twists the testis ligament, the epididymis and deferent duct lengthen and these structures are lined up in the direction of the peritoneo-vaginal process. The testis is generally situated in the newborn, on or near the internal ring. The gubernaculum testis is attached to the epididymis but does not exercise traction on the testis. The epididymis is a factor in this descending process.