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

Stereological study of testes following experimentally-induced unilateral cryptorchidism in rats

OBJECTIVE

Cryptorchidism is one of the main causes of infertility and can result in testicular cancer. This study aimed to present quantitative data on the damage caused by cryptorchidism using stereological analysis.

METHODS

Thirty newborn rats were randomly divided into control and experimental groups. The experimental group underwent surgery to induce unilateral cryptorchidism in the left testis, whereas the control group underwent a sham surgical procedure 18 days after birth. The testes were removed at designated time points (40, 63, and 90 days after birth) for stereological evaluation and sperm analysis. Total testicular volume, interstitial tissue volume, seminiferous tubule volume and length, and seminiferous epithelium volume and surface area were measured. Other parameters, such as sperm count, sperm morphology, and sperm tail length, were also examined.

RESULTS

Statistically significant differences (p<0.05) were observed between the experimental and the control groups at different ages regarding the volumes of various parameters, including the surface area of the germinal layer, the length of the seminiferous tubules, sperm count, and sperm morphology. However, no significant differences were observed in the epithelial volume and the sperm tail length of the groups.

CONCLUSION

Given the substantial effect of cryptorchidism on different testicular parameters, as well as the irreversible damage it causes in the testes, it is important to take this abnormality seriously to prevent these consequences.

Polygenic inheritance of cryptorchidism susceptibility in the LE/orl rat

STUDY HYPOTHESIS

Susceptibility to inherited cryptorchidism in the LE/orl rat may be associated with genetic loci that influence developmental patterning of the gubernaculum by the fetal testis.

STUDY FINDING

Cryptorchidism in the LE/orl rat is associated with a unique combination of homozygous minor alleles at multiple loci, and the encoded proteins are co-localized with androgen receptor (AR) and Leydig cells in fetal gubernaculum and testis, respectively.

WHAT IS KNOWN ALREADY

Prior studies have shown aberrant perinatal gubernacular migration, muscle patterning defects and reduced fetal testicular testosterone in the LE/orl strain. In addition, altered expression of androgen-responsive, cytoskeletal and muscle-related transcripts in the LE/orl fetal gubernaculum suggest a role for defective AR signaling in cryptorchidism susceptibility.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

The long-term LE/orl colony and short-term colonies of outbred Crl:LE and Crl:SD, and inbred WKY/Ncrl rats were maintained for studies. Animals were intercrossed (LE/orl X WKY/Ncrl), and obligate heterozygotes were reciprocally backcrossed to LE/orl rats to generate 54 F2 males used for genotyping and/or linkage analysis. At least five fetuses per gestational time point from two or more litters were used for quantitative real-time RT-PCR (qRT-PCR) and freshly harvested embryonic (E) day 17 gubernaculum was used to generate conditionally immortalized cell lines. We completed genotyping and gene expression analyses using genome-wide microsatellite markers and single nucleotide polymorphism (SNP) arrays, PCR amplification, direct sequencing, restriction enzyme digest with fragment analysis, whole genome sequencing (WGS), and qRT-PCR. Linkage analysis was performed in Haploview with multiple testing correction, and qRT-PCR data were analyzed using ANOVA after log transformation. Imaging was performed using custom and commercial antibodies directed at candidate proteins in gubernaculum and testis tissues, and gubernaculum cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

LE/orl rats showed reduced fertility and fecundity, and higher risk of perinatal death as compared with Crl:LE rats, but there were no differences in breeding outcomes between normal and unilaterally cryptorchid males. Linkage analysis identified multiple peaks, and with selective breeding of outbred Crl:LE and Crl:SD strains for alleles within two of the most significant (P < 0.003) peaks on chromosomes 6 and 16, we were able to generate a non-LE/orl cryptorchid rat. Associated loci contain potentially functional minor alleles (0.25-0.36 in tested rat strains) including an exonic deletion in Syne2, a large intronic insertion in Ncoa4 (an AR coactivator) and potentially deleterious variants in Solh/Capn15, Ankrd28, and Hsd17b2. Existing WGS data indicate that homozygosity for these combined alleles does not occur in any other sequenced rat strain. We observed a modifying effect of the Syne2(del) allele on expression of other candidate genes, particularly Ncoa4, and for muscle and hormone-responsive transcripts. The selected candidate genes/proteins are highly expressed, androgen-responsive and/or co-localized with developing muscle and AR in fetal gubernaculum, and co-localized with Leydig cells in fetal testis.

LIMITATIONS, REASONS FOR CAUTION

The present study identified multiple cryptorchidism-associated linkage peaks in the LE/orl rat, containing potentially causal alleles. These are strong candidate susceptibility loci, but further studies are needed to demonstrate functional relevance to the phenotype.

WIDER IMPLICATIONS OF THE FINDINGS

Association data from both human and rat models of spontaneous, nonsyndromic cryptorchidism support a polygenic etiology of the disease. Both the present study and a human genome-wide association study suggest that common variants with weak effects contribute to susceptibility, and may exist in genes encoding proteins that participate in AR signaling in the developing gubernaculum. These findings have potential implications for the gene-environment interaction in the etiology of cryptorchidism.

LARGE SCALE DATA

Sequences were deposited in the Rat Genome Database (RGD, http://rgd.mcw.edu/).

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by: R01HD060769 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD), 2P20GM103446 and P20GM103464 from the National Institute of General Medical Sciences (NIGMS), and Nemours Biomedical Research. The authors have no competing interests to declare.

Studies of cryptorchidism in experimental animal models

Undescended testes are the most common inborn anomaly in boys but our understanding of the causes is still sparse. Experimental models of cryptorchidism in various species of animals have been used by many investigators in order to gain a better understanding of the aetiology, pathophysiology and potential treatment of the disorder. This review presents what has been gained so far by studies using experimental animal models of cryptorchidism.

CONCLUSIONS

Early orchidopexy in experimentally cryptorchid animals of different species prevents, at least partially, against testicular damage and infertility. This supports an early intervention strategy in the management of cryptorchidism in humans although animal data on the correct timing of such treatment cannot be directly translated into human clinical practice due to the species differences in pre and postnatal testis maturation. Treatment with pharmacological doses of hCG has poor efficacy in experimental animals and may cause adverse effects. Thus, clinically relevant doses of hCG causes acute inflammation-like changes in rodent testes and there are also indications that it may induce morphologically detectable permanent testicular damage.

Effects of prenatal flutamide on testicular development, androgen production and fertility in rats

INTRODUCTION

To investigate the effects of blocking prenatal androgen with the anti-androgen flutamide on testicular weight (TW), seminiferous tubular diameter (STD), testicular biopsy score (TBS), testicular testosterone (TT), and fertility.

MATERIALS AND METHODS

Ten pregnant Wistar albino rats were injected with flutamide (100 mg/kg) on gestational days 16 and 19. Rats injected with the solvent were used as controls. Male pups from these dams were evaluated for testicular descent on postnatal day 22. The ability of each male to produce offspring was tested when the animals were aged 130 days. The rats were killed when 180 days old, and the testes were removed.

RESULTS

Sixteen of the 24 male rats (66.6%) exhibited cryptorchidism (6 unilateral, 10 bilateral) in the flutamide-treated group. Three of the rats with normally descended testicles were fertile, but none of the cryptorchid rats was fertile in flutamide-treated group. The average TW, mean STD, TBS and TT levels of the flutamide-treated rats was significantly lower than in the solvent-injected rats. However, there was no significant difference in these values between descended and undescended testes in flutamide-treated rats.

CONCLUSION

Blocking of prenatal androgen with flutamide interferes with testicular development by inhibiting testicular descent, and also effects testicular morphology and function in both the descended and undescended testes of rats.

Apoptosis and proliferation in human undescended testes

OBJECTIVE

To study apoptosis and proliferation in the testes of children with undescended testes; the degree to which undescended testes contributes to a patient's ultimate fertility is debatable, but undescended testes have fewer germ cells, and some have proposed that apoptosis is an important cause.

PATIENTS AND METHODS

Testis biopsies were taken at the time of orchidopexy in a consecutive series of children undergoing surgical repair for undescended testes. Immunohistological techniques were used to detect apoptosis and proliferation, and the numbers of cells undergoing apoptosis or proliferation per 50 seminiferous tubules were recorded.

RESULTS

Inguinal testes had less apoptosis than abdominal testes, with a mean (sd) of 0.71 (1.31) vs 1.63 (1.95) apoptotic cells per 50 seminiferous tubules (P < 0.02). Similarly, there was less apoptosis in children aged > 1 years than in children aged < 1 years (0.68 (1.40) vs 1.35 (1.56); P < 0.03). Proliferation was very limited in all cryptorchid testes. In contrast to cryptorchid testes, five autopsy controls had many more apoptotic cells, (10.60 (1.34) per 50 seminiferous tubules), and many more proliferating cells, (8.40 (6.43) per 50 seminiferous tubules).

CONCLUSION

In contrast to animal studies, neither apoptosis nor proliferation was common in undescended testes from 6 months of age onward. However, apoptosis was more common in abdominal testes and in children aged < 1 year. It is likely that, if substantial apoptosis occurs in human undescended testes, it occurs before 6 months of age.

The effects of orchidopexy and orchidectomy on testes of rats subjected to ipsilateral abdominal testis with vas deferens obstruction

An experimental study was planned to evaluate and compare the effects of orchidopexy and orchidectomy on the testes of rats subjected to unilateral abdominal testis with vas deferens obstruction. Four groups were established. Rats in the control group underwent a sham procedure. While the testis was maintained in the abdomen with the vas deferens ligated for 8 weeks in group 2, rats in groups 3 and 4 underwent orchidopexy or orchidectomy after 4 weeks. Remaining testes were harvested at the end of the 8-week period. Testis and body weights were obtained during harvest. Samples were evaluated through DNA flow cytometry, and percentages of haploid cells were determined. Groups were compared through unpaired t-test, and p-values less than 0.05 were considered significant. All three treatments had decreased testis weight over body weight values of ipsilateral testes. Ipsilateral orchidectomy increased the value among contralateral testes. However, none of the groups had a contralateral testicular value less than the sham-operated group. All three treatments decreased the percentage of haploid cells among ipsilateral testes, but only an abdominal testis was associated with a decrease in the percentage of haploid cells among contralateral testes. Maintaining a testis with an obstructed vas deferens in the abdomen for 8 weeks damages both ipsilateral and contralateral testes. Orchidopexy, while showing amelioration of the ipsilateral testis, spares the contralateral testis as well as orchidectomy. Orchidopexy for an undescended testis with vas deferens obstruction is a rational approach.

A stereological study of the effects of experimental inguinal cryptorchidism and subsequent orchiopexy on spermatogenesis in adult monkeys

Our previous study demonstrated that experimental intra-abdominal cryptorchidism in adult rabbits for 13 weeks resulted in severe spermatogenic arrest: type A spermatogonia was the only germ cell type seen in the seminiferous epithelium and its number per testis was reduced by 84%. Seven weeks following orchiopexy, the type A spermatogonial number returned to the near-normal range in most animals and spermatogenesis partially recovered (Reproduction 2002, 124, 95-105). This study aimed to determine whether inguinal cryptorchidism would produce less-severe damage to spermatogenesis and whether subsequent orchiopexy would better restore spermatogenesis. Five normal adult male rhesus monkeys (Macaca mulatta) underwent bilateral artificial inguinal cryptorchidism. Half a year later, one testis together with the ipsilateral epididymis were removed from each animal and then unilateral orchiopexy was performed on the contralateral side, with the remaining testis and epididymis being removed another half a year later. A contemporary unbiased and efficient stereological tool, the optical disector, was used to estimate numbers of all types of spermatogenic cells in the testis and spermatozoa in the epididymis. Spermatogenic arrest was induced by cryptorchidism at the stage of spermatogonia (n = 1), spermatocytes (n = 2) or early spermatids (n = 1), with the type A spermatogonial numbers per testis being reduced to 14.8-57.2% of the control average; in one of the five cryptorchid animals, however, spermatogenesis remained normal. Subsequent orchiopexy, which was successfully performed on two animals with cryptorchidism-induced spermatogenic arrest, brought on a full or partial recovery of spermatogenesis. In conclusion, inguinal cryptorchidism induces less severe (in comparison with an intra-abdominal one) and variable damage to spermatogenesis, which is restored, at least in part, by subsequent orchiopexy.

Cryptorchidism: fowler-stephens procedure or autotransplantation-a new experimental model

OBJECTIVES

To investigate the effect of different operative procedures on testicular development in cryptorchidism.

METHODS

One hundred ten postpubertal Wistar-WU rats were divided into four groups. Group 1 (35 rats) underwent microsurgical autotransplantation of the right testis with end-to-end anastomosis of the testicular vessels. Group 2 (35 rats) underwent the Fowler-Stephens maneuver with intra-abdominal fixation of the testis. To determine the influence of temperature on testicular development, group 3 (35 rats) underwent the Fowler-Stephens maneuver with scrotal replacement of the testis. Group 4 (5 rats) was a control group without operative treatment. To assess the early and late changes of testicular ischemia and reperfusion, groups 1 to 3 were divided into seven subgroups (5 rats each) with defined postoperative intervals (0.5 hour, 2 hours, 4 hours, 8 hours, 16 hours, 14 days, and 60 days). Testicular development, sperm density, pH value, tissue lactate concentration, and tubular diameter were the parameters used to determine success or failure.

RESULTS

After autotransplantation, testicular development exhibited an atrophy rate of less than 50% and a significant decrease in groups 2 and 3 after 60 days. The sperm density was significantly different between groups 2 and 4 (control). The pH value was significantly different after 2 hours in groups 2 and 3. The tissue lactate concentration revealed no significant differences. The tubular diameters were significantly diminished in group 2 after 60 days.

CONCLUSIONS

The smaller atrophy rate of the testes suggests that we successfully established a model in the rat to compare the operative outcome after autotransplantation and the Fowler-Stephens procedure in cryptorchidism. The significant difference in the tubular diameters for the intra-abdominally placed testes might be caused by the exposure of the testis to a higher temperature.

Effect of cryptorchidism on testicular histology in a naturally cryptorchid animal model

PURPOSE

To determine the effect of naturally occurring cryptorchidism on testicular histology in both the cryptorchid and normally descended testis from birth to adulthood using the LE/ORL rat model.

MATERIALS AND METHODS

Testicular histology was assessed using established morphometric measures in bilaterally descended (BD), unilaterally descended (UD), bilaterally cryptorchid (BC) and unilaterally cryptorchid (UC) testis at days 15, 22, 30, 45 and 60 of age. Testicular mass was also measured at these times.

RESULTS

Changes in testicular histology in the BC and UC testes were not noted on or prior to day 30 of age. Significant changes were noted by day 45 of age and continued into adulthood at day 60 of age. There were no histological abnormalities noted in the UD and BD groups.

CONCLUSIONS

Since histological changes seen in this animal model occur after the time of testicular descent (day 28 of age), we hypothesize that these changes are due to an abnormal anatomical position of the testis as opposed to an inherent testicular defect in the LE/ORL rat. This hypothesis is supported by the fact that no histological differences were noted between the scrotal testes of unilaterally cryptorchid animals and bilaterally descended control animals.

Avaliação dos efeitos da ciclofosfamida nos testículos escrotal e retido em ratos jovens submetidos à criptorquia unilateral

Foi produzida criptorquia unilateral experimental em ratos pré-puberais. Tanto no testículo retido quanto no contralateral escrotal, foram encontradas alterações similares às observadas cm seres humanos. Essas alterações correspondem a um desenvolvimento testicular prejudicado, com degeneração da gônada. A administração crônica da droga imunossupressora ciclofosfamida, em doses baixas, evitou a deterioração do testículo tópico, a despeito de sua reconhecida ação deletéria para a espermatogênese. Tendo em vista que as lesões observadas atingem também o testículo escrotal e podem ser prevenidas pela ciclofosfamida, e discutida a possibilidade de que sejam causadas por reação auto-imune.

Fertility potential after unilateral orchiopexy: an age independent risk of subsequent infertility when biopsies at surgery lack germ cells

PURPOSE

We evaluated whether adult fertility potential was better when unilateral orchiopexy was done at ages 2 to 6 years or later, and we identified those at risk for infertility.

MATERIALS AND METHODS

Unilateral orchiopexy was performed simultaneously with testicular biopsy in 11 patients 2.8 to 6.8 years old and in 54, 10.0 to 11.9 years old. In adulthood measurement of testicular volume, serum follicle-stimulating hormone, luteinizing hormone and testosterone was done, as well as analysis of semen specimens.

RESULTS

At orchiopexy the 2 groups were statistically similar, and statistically similar fertility potentials were found in adulthood. Five of the 65 patients (7.7%, 95% confidence limits 2.5 to 17%) may experience infertility, representing 33% of both groups with less than 1% of the age matched number of spermatogonia per tubular transverse section (approximately no germ cells) in the biopsy specimen at orchiopexy.

CONCLUSIONS

Between ages 2 and 12 years the timing of unilateral orchiopexy may vary without an effect on subsequent fertility potential. When biopsy at surgery lacks germ cells, there is an approximately 33% age independent risk of subsequent infertility. Otherwise patients may be fertile after unilateral orchiopexy between ages 2 and 12 years.

Division of the genitofemoral nerve in unilateral cryptorchid rats

The long-term effect of dividing the genitofemoral nerve supply to the undescended testis in naturally cryptorchid rats is reported. 20 male Buffalo rats with an undescended right testis, noted at the age of 30 days, were used for the investigation. 20 healthy animals served as controls. The abdominal division of the right genitofemoral nerve was performed in 10 cryptorchid and 10 healthy animals at the age of 40 days. The animals were mated at 150 days of age. Both testes were removed at 180 days of age. In each excised testis the testicular weight and seminiferous tubular diameters were measured, and the maturity of the germinal epithelium was determined using the Johnsen testiscular biopsy score. The experiment showed that in 70% of the nonoperated cryptorchid rats, both testes were affected at the age of 180 days, and 90% of these animals were infertile. In the operated cryptorchid rats, the contralateral descended were not damaged, and 60% of these animals were fertile. The division of the genitofemoral nerve in healthy animals had no effect. The results suggest that neural transmissions might play a role in the damage to the descended testis in unilateral cryptorchidism. This observation requires further investigations.