COMPARISON OF TESTICULAR PROTEIN LABELLING IN CRYPTORCHIDISM INDUCED IN PREPUBERTAL AND ADULT RATS

{Received 1st March 1965) Summary. Unilateral cryptorchidism has been produced in prepubertal rats by abdominal fixation of an undescended testis and in adult rats by transplantation of a previously descended testis from the scrotal sac into the abdominal cavity. The incorporation of l-lysine-U-14C into protein of slices of both types of experimentally induced cryptorchid testes 30 days following the surgical procedure has been found to be markedly greater than that observed for slices of contralateral, scrotal testes of the same animal. It has long been known that cryptorchidism leads to severe spermatogenic damage. In addition, the undescended testis has been reported to be over thirty times more likely to become malignant as compared to a normal, scrotal testis (Campbell, 1942). For these reasons, our laboratory has initiated studies on the metabolism of mammalian testicular tissue beginning with an investiga¬ tion of the incorporation of 14C-labelled lysine into rat testicular protein. It was initially found that the incorporation of L-lysine-U-14C into protein of slices of cryptorchid testes which were experimentally-induced in adult rats was much greater than that observed for slices of scrotal testes obtained from the same animal (Davis, Morris 8c Hollinger, 1964). The present experiments were designed to explore further this finding, as well as to investigate the physiological significance of inducing cryptorchidism by transplanting a previously descended adult testis from the scrotal sac into the abdominal cavity. Unilateral cryptorchidism was experimentally produced in two groups of male Sprague-Dawley rats. The first group (five animals) consisted of prepubertal rats which were 20 days of age and in which the testes had not yet begun their descent. Abdominal fixation of the undescended testis was carried out by performing a midline abdominal incision under ether anaesthesia and suturing the right testis to the dorsolateral abdominal wall, thereby preventing its normal descent. A fine 6-0 surgical silk suture was passed just under the