Extraabdominal fixation of the gubernaculum inhibits testicular descent in newborn rats

Protective effect of α-tocopherol on damage to rat testes by experimental cryptorchidism

It is thought that the degeneration of germ cells associated with an increase in the temperature due to cryptorchidism involves oxidative stress. α-Tocopherol is a powerful antioxidant that prevents oxidation of polyunsaturated fats found in membranes and stabilizes peroxyl radicals. For this reason we were interested in determining the role of α-Tocopherol using experimental cryptorchidism, followed by orchidopexia in neonatal rats. Eighty-four, 10-day-postpartum (dpp) male rats (Wistar strain) were used and divided into 7 groups: healthy control, sham with α-Tocopherol treated with 30 or 100 mg/kg doses, sham vehicle, cryptorchidism treated with α-Tocopherol at 30 or 100 mg/kg doses and cryptorchidism vehicle. Cryptorchidism was surgically induced at 10 dpp. At 25 dpp the animals were treated with α-Tocopherol and the vitamin vehicle. Lipoperoxidation and testicular morphology was determined in half of the animals at 40 dpp (short term). The remaining animals underwent orchidopexia and fertility was determined at 90 dpp. Testicular morphology was determined at 120 dpp (long term) in these animals. A significant reduction of lipoperoxidation was observed in the cryptorchid group treated with α-Tocopherol compared to the untreated cryptorchid group, in addition to short-term histological alterations. At long term, we observed an increase in the area and maturation of the seminiferous epithelium, a decrease in apoptosis and histological alterations and an increase in fertility from α-Tocopherol treatment. α-Tocopherol treatment decreased lipoperoxidation, possibly stabilizing free radicals produced during cryptorchidism, reducing morphological testicular alterations and favoring fertility.

Effect of allopurinol on damage caused by free radicals to cryptorchid testes

Cryptorchidism causes apoptosis of germ cells. It has been suggested that the redox regulatory system is involved in this process. The free radicals produced are thought to be generated during the production of uric acid, a reaction catalyzed by xanthine oxidase. This enzyme is inhibited by allopurinol; however, the role of allopurinol in neonate rats with inguinal cryptorchidism has not been assessed yet. Sixty male Wistar rats were used and five groups were formed: a control, a sham, a sham group with allopurinol administration and two groups with surgical unilateral cryptorchidism, which either did not receive, or received, allopurinol. The rats were assessed at 40 days post-partum. Reactive oxygen species concentration and epithelial area were measured and the histopathological, apoptotic and cellular proliferation indexes were determined. We found a decrease in reactive oxygen species, histopathological and apoptotic indexes and an increase in proliferation index and epithelial area in rats with cryptorchidism treated with allopurinol in comparison with rats with untreated cryptorchidism. We suggest that the over-production of reactive oxygen species plays an important role in the damage of the cryptorchid testes. Allopurinol administration decreases reactive oxygen species concentrations as well as the damage to the germ epithelium.

Avaliação macro e microscópica dos testículos em modelo experimental de criptorquidia pela secção do Gubernaculum testis em ratos

OBJETIVO: Verificar o efeito da secção distal do Gubernaculum testis como modelo experimental de criptorquidia unilateral em ratos. MÉTODO: Foram usados 36 ratos machos de linhagem Wistar-EPM, distribuídos em dois grupos: A (Grupo Experimento: animais submetidos à secção distal do gubernaculum direito) e B (Grupo Controle: operação simulada do lado direito). Cada grupo foi subdividido em 3 subgrupos com 6 animais cada : A-1, A-2 e A-3: B-1, B-2 e B-3. Os animais dos subgrupos A-1 e B-1 foram re-operados após 30 dias. Os animais dos subgrupos A-2 e B-2 foram mortos após 50 dias e os dos subgrupos A-3 e B-3 após 90 dias. RESULTADOS: Houve diferenças quanto ao peso, tamanho e posição do testículo afetado em relação ao lado controle,as quais só foram evidenciadas a partir do subgrupo A-2 (50 dias).O testículo não foi palpável na bolsa testicular em 88,9% dos casos e não houve óbito dos animais. Foram observadas alterações da maturidade celular, atrofia tubular, diminuição do diâmetro dos túbulos e ausência de espermatozóides na luz tubular no grupo A e presença de normalidade histológica para a idade nos animais do grupo B. CONCLUSÃO: O modelo experimental de produção de criptorquidia experimental unilateral pela secção do Gubernaculum testis em ratos foi eficaz e prático.

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.