Fertility in experimental unilateral cryptorchidism

Fertility and histological studies of the contralateral testes in two different intra- and extra-abdominal rat models of unilateral cryptorchidism

OBJECTIVE

To investigate the effect of location of the testis on both testicular development and fertility in unilateral cryptorchidism.

MATERIAL AND METHODS

Forty-nine Wistar King A newborn male rats were divided into three groups. In group 1 (15 rats) intra-abdominal unilateral cryptorchidism were created by the intra-abdominal fixation of the testis in the neonatal period. In group 2 (16 rats) extra-abdominal unilateral cryptorchidism was created by extra-abdominal fixation of the gubernaculum in the neonatal period. In group 3, 18 rats underwent a sham operation as controls. At 90 days of age, fertility was then assessed in each rat by housing it with two mature virgin females for 2 weeks. Thereafter, at 115-120 days of age, the rats were killed and their testes removed for histological examination.

RESULTS

There was no significant difference in the pregnancy rate between females coupled with rats from any group, but the mean number of offspring was significantly lower in females coupled with rats in group 1 than in group 2. Furthermore, histological examination of both the cryptorchid and contralateral scrotal testes showed more severe changes in the intra-abdominal than the extra-abdominal testes.

CONCLUSION

These results suggest that intra-abdominal cryptorchid testes are significantly more impaired than extra-abdominal cryptorchid testes, and that such impairment might be caused by exposure of the testis to a higher temperature. The more severely impaired undescended testes may thus induce the degeneration of the contralateral scrotal testis and thereby cause subfertility in the intra-abdominal unilateral cryptorchid rat model.

Fertility and histological studies in a unilateral cryptorchid rat model during early and late adulthood

OBJECTIVE

To investigate the effect of age on fertility and testicular development in rats with untreated unilateral undescended testes.

MATERIALS AND METHODS

Newborn male Wistar King-A rats were divided into two groups. In group 1, a mechanical model of unilateral undescended testis was created by performing extra-abdominal fixation of the gubernaculum in the neonatal period, and in group 2, sham-operated rats were used as controls. At 90 days old (early adulthood), the fertility of both groups was assessed by mating the rats with mature virgin females for 2 weeks. Thereafter, some of the rats were killed and their testes examined histologically, while the remaining rats were allowed to develop further. At the age of 180 days (late adulthood), fertility was re-assessed in the same way. All the rats were then killed and their testes removed for histological examination.

RESULTS

There was no significant difference in pregnancy rate of females mated with males from either group in early adulthood. However, in late adulthood there was a significant reduction in pregnancy rate in females coupled with cryptorchid rats compared with that of females coupled with control rats. There was a significant degeneration of the unilateral cryptorchid testes compared with control testes in both early and late adulthood. In contrast, there were no significant changes in histological development between the contralateral scrotal testes and the controls in early adulthood, although they were significantly different from the controls in late adulthood.

CONCLUSION

These results suggest that fertility is affected by ageing in untreated unilateral cryptorchidism; this may be induced by extensive damage not only in the undescended testes, but also in the contralateral scrotal testis, in this mechanically induced model of unilateral cryptorchidism.

Degenerative changes in spermatogonia are associated with loss of glucose transporter (Glut 3) in abdominal testis of surgically induced unilateral cryptorchidism in rats

Expression of facilitative glucose transporters (Glut 1, 2 and 3) was examined by Western blot analyses 10, 20 and 30 days following surgically induced unilateral abdominal cryptorchidism. The cryptorchid testes exhibited marked degenerative changes in the seminiferous tubules and spermatogonia, impaired and incomplete spermatogenesis and lack of spermatozoa in the lumen. Immunoblotting of testis proteins with Glut transporter antibodies revealed only the presence of Glut 2 and 3 proteins. Glut 2 expression in abdominal testis was increased (45%, 67%, and 40% at 10, 20 and 30 days, respectively) but no significant change was observed in contralateral scrotal testis. Glut 3 expression was reduced by 85-95% compared with contralateral scrotal testis. A significant decrease in Glut 3 levels in abdominal testis was accompanied by an increase in scrotal testis Glut 3 content (80%, 144% and 212% at 10, 20 and 30 days, respectively) compared to age matched control rats. These results suggested that the degenerative changes in abdominal testis may be associated with decreased Glut 3 mediated glucose transport in seminiferous tubules and spermatogonia.

The pharmacological effect of the gonadotrophin-releasing hormone on experimental cryptorchidism in rats

Cryptorchidism is the most frequent congenital disturbance in males requiring both medical and surgical interventions. The involved testicle shows severe pathological changes. In an effort to test new medical treatments, we established a rat model for induced cryptorchidism using two estradiol treatment regimens and evaluated the effects of GnRH and an analogue D-Phe-GnRH on rate of testicular descent and on improvement of abnormal testicular histology. We found that the duration of estradiol treatment and not the total dose was related to delayed recovery from testicular descent. No significant effect of GnRH on testicular descent was observed. D-Phe-GnRH significantly improved the rate of testicular descent in rats treated 40 days with estradiol, but not in those treated 30 days with estradiol. The histologic examination of estradiol-induced undescended testes revealed severe morphological changes with a low number of germ cells, infiltration with lymphocytes, fibrosis and smaller diameter of seminiferous tubules. These changes were not improved with GnRH. D-Phe-GnRH was able to correct some of the histologic changes of estradiol-induced cryptorchidism. We established an animal model for testing of medical treatments for cryptorchidism. Our study may be indicative of a new treatment strategy using D-Phe-GnRH in the non-surgical treatment of cryptorchidism in human.

Fertility and unilateral undescended testis in the rat model

Fertility potential in patients with unilateral (UL) undescended testis is a debated topic. An experimental study was done in rats by surgically creating a UL undescended testis and studying its effect on their potential to father offspring when housed with female rats. No difference in fertility potential was observed in the various groups in this study. Since fertility was tested immediately after the rats became mature, it could be possible that fertility might decrease if the rats were tested in later adulthood. We conclude that experimentally created UL undescended testis does not cause damage sufficient to result in infertility in young adult rats. Also discussed is the significance of this finding in relation to UL undescended testis in humans.

Anatomical and clinical correlation with histological and histometric patterns in cryptorchism

One feature rarely included in studies on cryptorchism is an adequate correlation between anatomical and clinical data and histological patterns of the testis. The present study correlates anatomical and clinical data from 50 patients (age range 2 months-14 years) using 4 different histological and histometric patterns established previously. Three different patterns of progressively severe histological changes corresponding to increasingly marked dysgenetic alterations in the anatomical and clinical patterns were detected. Less severe changes were correlated with mature anatomical and clinical features, whereas testes showing severe histological-histometric changes were correlated with immature anatomical and clinical features. Non-abdominally located testes with Sertoli cell hyperplasia were not significantly correlated with any of the anatomical and clinical features. The histometric patterns described should facilitate the diagnosis of the stage of testicular development on the basis of anatomical and clinical data.

The natural course of cryptorchidism in rats and the efficacy of orchidopexy or orchidectomy in its treatment before and after puberty

Both clinical and experimental evidence suggest that fertility is impaired in unilateral cryptorchidism. To investigate the effect of the undescended testis on the contralateral descended gonad, a new experimental model based on natural cryptorchidism in rats was designed. Seventy male Buffalo rats with an undescended right testis noted at the age of 30 days were used. Fifty healthy animals served as a controls. The natural course of cryptorchidism was investigated at the ages of 30, 90, and 180 days. The effects of orchiopexy and orchiectomy performed in cryptorchid animals before and after puberty were evaluated at the age of 180 days. Both nonoperated and operated animals were mated at the age of 150 days in order to estimate their fertility. The animals were killed at 30, 90, and 180 days of life and the testes were removed. In each excised testis testicular weight and seminiferous tubular diameters were measured and the maturity of the germinal epithelium was determined using the Johnsen testicular biopsy score. The experiment demonstrated reduced testicular weight and seminiferous tubular diameters in undescended testis already at 30 days and arrest of spermatogenesis at the spermatocytes stage at 90 and 180 days. There was no significant difference between contralateral descended testes and controls at the age of 30 and 90 days, but at 180 days the degenerative changes were identical with those in the cryptorchid testes. Cryptorchid rats were completely infertile. Both orchiopexy and orchiectomy prevented the damage to the contralateral testis. A significant improvement in size and spermatogenesis was recorded in most cases of the surgically descended testes.(ABSTRACT TRUNCATED AT 250 WORDS)