The Hutson hypothesis. A clinical study

The hypothesis that testicular descent may be governed by Müllerian inhibiting substance (MIS) was investigated by observing the position of the testes in 13 children with XY karyotype and persistent Müllerian duct syndrome (PMDS). It was found that there was a direct relationship between failure of testicular descent and the degree of development of the Müllerian system. Where the Müllerian system was complete, the testes were in an ovarian position but where only the vagina was present, the testes were sometimes found in the inguinal region. To discover whether excessive androgen activity in females might produce ovarian descent, the position of the ovaries in 15 children with severe adrenogenital syndrome was observed. Despite complete genital masculinisation in three children and almost complete in six, all but one ovary was in the normal position: that ovary had descended in an inguinal hernia sac. These findings suggest that MIS rather than androgens may be responsible for the first or abdominal phase of testicular descent. Even excessive androgen activity failed to cause ovarian descent.     

Testicular feminization: a model for testicular descent in mice and men

The position of the testis was determined in patients and mice with the testicular feminization (TFM) syndrome, to answer the question, do androgens cause testicular descent? In 16 children with complete or partial TFM syndrome with androgen insensitivity, plus two children with a deficiency of androgen secretion, the testes were at or beyond the internal inguinal ring in 35 out of 36 instances. In male mice with TFM, the testes had descended normally to the internal ring by the time of birth but further descent was absent. These observations suggest testicular descent is a two-stage process comprising transabdominal and transinguinal phases. The first phase is not controlled by androgen, and hence is normal in TFM; by contrast the second phase is androgen-dependent, and absent in TFM. It is speculated that the first phase may be regulated by Müllerian Inhibiting Substance, although this is unproven. Because testicular descent in TFM can be separated into two stages, the TFM mouse should prove a useful model for studying the hormonal control of descent of the testis.     

Molecular and anatomical studies of testicular descent

The mechanism of testicular descent is multifactorial, and the process is known to occur in two steps accompanied by different anatomies and hormonal regulation. In the first step, the testis descends from the lower pole of the kidney to the pelvic cavity near the bladder neck as a result of the swelling reaction of the gubernaculum. Next, in the second step, the testis descends into the scrotum through the inguinal canal via the gubernacular migration. The first step is androgen-independent, whereas the second step depends on the androgen action. Recently, several molecular studies on testicular descent have been reported. Several factors, such as androgen, calcitonin gene-related peptide (CGRP), epidermal growth factor (EGF), Hoxa-10 and insulin-like factor 3 (INSL3) have been suggested to be possible regulators of testicular descent. Because cryptorchidism has been frequently shown in androgen-insensitive human and mice (TFM-mice), androgen has been thought to play an important role in testicular descent. CGRP, which is released from the genitofemoral nerve, has been suggested to mediate the inguinoscrotal testicular descent. The epidermal growth factor (EGF) may promote both testosterone-induced wollfian duct differentiation and testicular descent by activating the androgen responsive systems. In male mice, a targeted disruption of the HOXA 10 gene causes cryptorchidism and the cryptorchid testes in these mutant mice are located in the lower abdominal cavity, whereas the cryptorchid testes in male mice lacking the INSL3 gene or its receptor Lgr8 were located in the abdominal cavity high. Recently, estrogens or environmental endocrine disruptors have also been suspected to induce a down-regulated INSL3 expression and thus disturb testicular descent.     

Anatomical findings at orchiopexy

The anatomical findings at orchidopexy for cryptorchid testis were recorded for 60 boys aged between 6 months and 18 years. In 11 patients (18.3%) bilateral cryptorchidism was present. At operation, atrophied testicular tissue was found in two patients and one testis was found to be absent; 69.1% (47/68) of the remaining testes were found in the superficial inguinal pouch at operation, 27.9% (19/68) were in the inguinal canal, one was in the femoral triangle and one was high in the scrotum. In 35 testes (51.5%) there was an associated hernial sac. In 54 testes (79.4%) the gubernaculum testis was attached to an anatomical site other than the lower scrotum. In 26 (38.2%) there was a fascial block to descent into the scrotum and one or other of these findings was present in 64 testes (94.1%). These findings suggest that failure to establish a patent route from the superficial inguinal region to the scrotum and the passage of the gubernaculum along this route are the abnormalities responsible for failure of testicular descent.     

Androgen-induced prevention of the outgrowth of cranial gonadal suspensory ligaments in fetal rats.

Normal and disturbed testicular descent is frequently approached exclusively through a consideration of the caudal testicular suspensory apparatus. This is surprising, because embryonal gonads develop with both cranial and caudal suspensory ligaments, and the sexes differ with respect to the persistence and development of both the cranial and the caudal ligaments. The current study examined the possible role of fetal testicular androgens in male-specific failure of the development of the cranial gonadal suspensory apparatus in rats. Normal male fetuses were studied, as well as fetuses exposed to the anti-androgen flutamide from day 10 after conception. Females were given daily injections of methyl-testosterone alone or in combination with the anti-androgen cyproterone acetate from day 15 after conception, and were studied on day 22. The cranial ligaments remained of minor extension in normal males but developed considerably in females. They developed in female fashion in males exposed to flutamide, and persisted throughout postnatal life. Cranial ligaments did not develop in females that had been exposed to methyl-testosterone. Simultaneous treatment with a large dose of cyproterone acetate effectively counteracted this effect. Fetal testicular testosterone thus appears to play a key role in the prevention of the outgrowth of the cranial gonadal/genital ligament in rats. The supposed function of this suspensory apparatus makes it likely that its persistence in males, as the consequence of inappropriate androgen action during fetal life, facilitates disturbance of testicular descent. This finding may contribute to understanding developmental disorders underlying disturbed testis descent in humans.     

Differential expression of androgen and estrogen receptor of appendix testis in patients with descended and undescended testes

Objectives:   The incidence of appendix testis has been shown to be 76% in descended and 24% in undescended testis in our previous intraoperative survey. To determine the possible role of the appendix testis in the process of testicular migration, we compared the androgen and estrogen receptor status of appendix testis in descended and undescended testes.
Methods:   Thirty-seven appendix testes were collected intraoperatively and the expression of androgen and estrogen receptors were examined with immunostaining and immunofluorescence labeling. Based on the diagnosis, the specimens were divided into three groups. Group H (groin hernia, n  = 11, as a group of descended testis), Group AU (acquired undescended testis, n  = 14), and Group CU (congenital undescended testis, n  = 12).
Results:   The testicular appendages were found to express both androgen and estrogen receptors in Group H and Group AU, but specimens in Group CU were only estrogen receptor positive, whereas androgen receptors were not present.
Conclusion:   The presence of the androgen receptor in the appendix testis of the descended testes and acquired undescended testes and its absence in patients with congenital undescended testis suggests that the appendix testis might play a role in the process of testicular descent.     

The predictive value of inguinal herniography for the diagnosis and treatment of cryptorchidism

PURPOSE: We evaluated the role of a patent processus vaginalis for cryptorchidism as well as inguinal herniography as a predictor of the efficacy of human chorionic gonadotropin (HCG) treatment. MATERIALS AND METHODS: We studied 244 boys with unilateral and 66 with bilateral cryptorchidism. All patients underwent inguinal herniography and received HCG. Nonresponders to treatment subsequently underwent orchiopexy, when processus vaginalis status, testicular position and epididymal characteristics were assessed. RESULTS: HCG was effective for 139 of 281 testes (49.5%) with an obliterated and 0 of 95 with a patent processus vaginalis on herniography. We further evaluated herniography in accordance with orchiopexy findings of persistent unilateral and bilateral cryptorchidism in 206 boys (237 testes) after HCG. Herniography findings of processus vaginalis morphology revealed a close correlation with that reported by the surgeon after orchiopexy (p<0.000005). The incidence of a patent processus vaginalis increased as testicular position became more caudal. The processus vaginalis was obliterated in all cases of anorchia. The incidence of more severe epididymal anomalies decreased as the testicular position became more caudal. Epididymal abnormalities were more common when the processus vaginalis was patent. CONCLUSIONS: Pretreatment herniography assessment of processus vaginalis morphology is of prognostic value for predicting the efficacy of hormone treatment, the presence or absence of testes when they are nonpalpable and future fertility.     

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.     

Effect of division of genitofemoral nerve on testicular descent in the rat

The gubernaculum, which has an important role to play in testicular descent, is richly supplied by the genital branch of the genitofemoral nerve through its scrotal attachment. In neonatal rats the genitofemoral nerve overlying the psoas muscle was divided before inguinal descent would normally occur, and the effect of this procedure on subsequent testicular descent was observed. Denervation of the gubernaculum caused the testes to remain in the abdomen. The significance of this finding in the rat is that an intact genitofemoral nerve is an essential prerequisite for normal descent, perhaps by allowing the gubernaculum to evert.     

Morphological and Endocrinological Differences between the Abdominal Testes in Bilateral and Unilateral Cryptorchid Rats

Using a new experimental model of cryptorchism in rats, where testicular descent was prevented, testicular development and function were studied in bilateral and unilateral cryptorchid animals Morphometric and radioimmunological techniques were used. Up to 30 days after birth testicular development was identical in the two types of abdominal testes but in adult rats differences were observed. In these rats spermatogenesis was damaged to a similar extent, but total tubular length and testicular weight were increased in the bilateral abdominal testes. Moreover, in these testes, the volume density of Leydig cells, the total Leydig cell mass, the average Leydig cell size and the testis testosterone concentration were larger than in unilateral abdominal testes. It is suggested that the impaired spermatogenesis seen in both kinds of abdominal testes may be unrelated to Leydig cell function.     

Testicular cancers occurring in brothers with cryptorchism

We report a case of familial testicular cancer associated with undescended testes in two brothers. The older brother (49 years) presented with a testicular tumor located in the right inguinal canal. The pathologic diagnosis was pure seminoma. Computerized tomography revealed iliac and retroperitoneal lymph node metastases. Four years later, the younger brother (44 years) developed bilateral testicular tumors, one located in the inguinal canal, the other located in the pelvic cavity. The pathologic diagnosis of both tumors was pure seminoma. Radiological examination revealed retroperitoneal lymph node metastases. Both patients received cisplatin-based combination chemotherapy as the initial treatment. The older brother suffered from repeated recurrences with lymph node metastases in the iliac and inguinal regions, but he was successfully treated with high-dose chemotherapy. The younger brother achieved long-term remission after retroperitoneal lymph node dissection following initial chemotherapy. We briefly review the reported cases of familial testicular cancer and discuss the association of the maldescent of the testes and familial testicular cancer cases.     

Effect of the antiandrogen, WIN 49,596, on the descent of the testis in the male rat

Testicular descent in the male rat is believed to be an androgen dependent event with dihydrotestosterone the most likely active androgen. To provide further insight into the endocrinology of this important physiological event, we treated male rats with the antiandrogen, WIN 49596 (50 mg./kg./day), from day 1 to day 27 of age and evaluated its effect on the post-natal androgen-dependent events in this animal model. It was determined that while treatment with WIN inhibited the weights of the ventral prostate, seminal vesicles and penis when compared to those seen in castrate animals, the drug only caused a 19% (3/16) inhibition in the descent of the testes when compared to the control group (0/16; p = 0.112). These data together with those previously obtained in animals exposed to selective inhibitors of the 5-alpha reductase enzyme suggest that other factors possibly working in tandem with androgens play a predominant role in testicular descent in the rat.     

Impalpable testes: a review of 100 boys

A consecutive series of 100 boys with 104 impalpable testes is reviewed. Extended inguinal exploration was the main form of investigation and treatment. Hormone injections and studies were performed in bilateral cases and in the latter part of the series, laparoscopy supplemented inguinal operation. Sonography was unhelpful. Seventy-five testes were found, 34 in the abdomen, 34 in the inguinal canal, and 7 below the external ring. Seventeen of the abdominal testes, 31 of the inguinal testes, and all of those below the external ring were successfully brought to the scrotum. In ten boys no trace of testis was found and in 19 there was testicular or cord "remnant." Laparoscopy was performed before inguinal exploration in eight and it is concluded that this procedure is helpful but of limited value. It is indicated where no testis or testicular vessels are found on inguinal exploration and this occurs in about 15% of impalpable testes. When an atrophic testis is found, it is not evident whether the testis is agenetic or whether its disappearance resulted from torsion so fixation of the contralateral testis is recommended in all such patients.     

Comparison of ultrasonographic and laparoscopic findings in adult nonpalpable testes cases

OBJECTIVE: There is a small number of studies in adult nonpalpable testes cases, and there is no published paper on the diagnostic value of their ultrasonographic examination. In this prospective study, we compared the sonographic and laparoscopic findings in adult cases with nonpalpable testes to assess the necessity and the profits of ultrasound. MATERIALS AND METHODS: 50 cases, 38 unilateral and 12 bilateral, with nonpalpable testes were investigated. Patients' ages ranged from 20 to 25 years with a mean of 22. Sonographic examinations were performed with a high-resolution ultrasonography device. RESULTS: Laparoscopic evaluation of the patients with unilateral nonpalpable testis yielded 27 testes out of a total 38. In one case, the testis was detected in the inguinal canal with inguinal exploration. The remaining 10 cases were regarded as vanishing testes. All 24 testes of 12 patients with bilateral nonpalpable testes were found. The pre-laparoscopic ultrasonographic examination detected 20 of 24 testes in bilateral cases (83% sensitivity), and 17 of 26 testes in unilateral cases (65% sensitivity). CONCLUSION: Our results suggest that ultrasonography does not exclude the necessity for laparoscopy, and it is not superior to physical examination in detection of the inguinal atrophic testes or testicular nubbin.     

Human chorionic gonadotrophin hormone for treatment of congenital undescended testis: Anatomical barriers to its success

Background/PurposeAlthough the surgical treatment was proved to be the recommended line of management for congenital undescended testis, hormonal therapy with human chorionic gonadotrophin hormone has been started long years ago and is still used in some areas with variable degrees of success. The factors responsible for treatment failure are not well explored. In this study, we aimed to highlight the anatomical abnormalities in the congenital undescended testis that might contribute to treatment failure.MethodsDuring the period from January 2014 to December 2015, 75 boys with congenital undescended testes received treatment with human chorionic gonadotrophin, in pediatric surgery department, Faculty of medicine, Ain Shams University. Their age ranged between 6 months and 4 years (mean 1.6 years, median 2 years). In 70 boys, the testes were palpable and in the remaining 5 boys, the testes were impalpable. Fifty boys had unilateral and 25 had bilateral undescended testes. Seven of the palpable testes were high scrotal in position and the remaining 83 were palpated in the inguinal canal. The patients were followed up for 6 months to determine the position of the testis after the treatment and surgical intervention was done for those who did not respond to the hormonal treatment either partially or completely.ResultsOnly 7 testes showed complete descent (7%) (2 bilateral and 3 unilateral) and they were initially high scrotal in position, 8 testes showed partial descent (8%) (2 bilateral and 4 unilateral) and they were inguinal in 6 which became high scrotal and impalpable in 2 which became peeping. The remaining 85 (85%) did not respond to the hormonal treatment. Upon surgical exploration, abnormal attachment of the gubernaculum was found in 83 testes (83%), 2 testes were peeping (2%), short testicular vessels were found in 4 testes (4%), 3 testes were vanishing (3%) and a closed internal ring was found in one testis (1%).ConclusionsTreatment of congenital undescended testis with human chorionic gonadotrophin hormone had low success rates. Anatomical abnormalities in the congenital undescended testis might contribute to this treatment failure.Type of the studyClinical research paper.Level of evidencelevel III.     

Inguinal cordopexy: a simple and effective new technique for securing the testes in reoperative orchiopexy

BACKGROUND/PURPOSE: A new procedure is described for securing the testis in the scrotum in patients with a past history of inguinal sugery and testes in an unsatisfactory position. METHODS: Twenty-seven patients with 29 abnormally positioned testes (two bilateral) were evaluated. All patients had a past history of inguinal surgery, and ages ranged between 4 and 16 years (mean, 7.2). Previous surgical procedures included 23 orchiopexies, 4 inguinal herniorrhaphies, and 2 testicular detorsions of undescended testis. In all reoperations an attempt was made to fix a strip (two nonabsorbable stitches) of the fascia attached to the cord, to the pubic bone, or to the tendinosous part of the gracilis muscles (cordopexy), so that the distal part of the cord and the testis lay freely in the scrotum without tension. Patients underwent follow-up every 6 months after the operation with physical and ultrasound examinations. RESULTS: Cordopexy was possible in 11 (38%) of the 29 inguinal reoperations. In all cases, orchiopexy was the previous surgical procedure. One hundred percent of the testes remain within the scrotum after a mean follow-up of 21 months (range, 8 to 38). CONCLUSION: When feasible, inguinal cordopexy is a simple and effective technique for securing testicles in reoperative orchiopexy procedures.     

The Gubernaculum in adult female, adult male and TFM male mice

There is still controversy over whether androgens are involved in gubernacular migration during descent of the testis, prompting a review of anatomical events controlled by androgens. The gubernacular position in adult female, male, and testicular feminized male (TFM) mice (with complete androgen resistance) was observed macroscopically to determine its caudal limit and whether the adult TFM male still contained guvernacular bulk. The length of the processus vaginalis was measured, and the presence of a differentiated cremaster muscle was determined histologically. In 10 adult female mice there was neither a processus vaginalis nor a cremaster muscle, and the gubernaculum (round ligament of the ovary) attached to the external inguinal ring. In 10 adult TFM mice the gubernaculum ended at or just beyond the external ring, and was present in an amount corresponding to its size at the end of the outgrowth phase of development, with secondary infiltration by fat. The processus vaginalis was poorly developed, the cremaster muscle was undifferentiated, and there was no eversion of the cremaster sac. In 10 normal adult male mice the gubernaculum and testis had migrated to the scrotum, and the gubernaculum had regressed fully. Because gubernacular development in the androgen-resistant mouse ceases after termination of transabdominal testicular migration, the anatomy of the adult confirms that, in the mouse, normal androgenic function is essential for eversion of the cremaster sac and gubernacular migration beyond the groin to the genital folds.     

Hoxa-11 maintains cell proliferation in the mouse gubernaculum to facilitate testicular descent

Introduction

The gubernaculum is a structure vital for guiding testicular descent. The Homeobox gene, Hoxa-11, is involved in patterning embryonic structures and is necessary for gubernacular development, as Hoxa-11 knock-out mice exhibit abnormal gubernacula and undescended testes. We aimed to elucidate how testicular descent fails by examining cell proliferation and androgen receptor (AR) expression in Hoxa-11 KO mice gubernacula.

Methods

Postnatal day 2 wild type (n = 6) and Hoxa-11 KO mice (n = 6), were prepared for immunohistochemistry and confocal microscopy using antibodies against androgen receptor, slow skeletal myosin (My32), and Ki67, a marker of cell proliferation.

Results

The gubernacula of Hoxa-11 KO mice were hypocellular compared with WT. AR was present in the gubernaculum and abutting inguinal fat pad in both WT and Hoxa-11 KO with no difference in expression. Slow skeletal myosin was present in a clear ‘swirl’ in the growth centre of WT animals which was absent in the Hoxa-11 KO mice. Ki67, expressed in the growth centre and cremaster muscle in WT, was greatly decreased in Hoxa-11 KO.

Conclusion

Hoxa-11 may regulate fibroblast proliferation in the gubernaculum, as it does in human uterosacral ligaments, allowing formation of the 'growth centre' within the bulb and facilitating myogenesis and elongation to the scrotum. Polymorphisms in Hoxa-11 may contribute to the aetiology of human cryptorchidism.     

The difficult orchidopexy: the value of the abdominal pre-peritoneal approach

OBJECTIVE: To analyse the outcome of using the abdominal pre-peritoneal (APP) approach to orchidopexy. PATIENTS AND METHODS: During an 8-year period, the experience of one surgeon in the management of 553 boys (median age 4.5 years, range 1-13) with undescended testes (596 testes) was assessed. The analysis emphasized those patients who had an orchidopexy performed using the APP approach detailing; the original position of the testis at exploration, whether successful placement within the scrotum was possible, and whether atrophy or ascent of the gonad occurred subsequently. RESULTS: In 98 boys (110 testes) the testes were impalpable or high within the inguinal canal and they were explored using the APP approach. Of the 34 testes (31%) which were found abdominally, 12 were high intra-abdominal and the remaining 22 just deep to the internal inguinal ring. These included seven bilateral and 20 unilateral intra-abdominal testes. The remaining 76 undescended testes included five with bilateral high testes, 29 high unilateral testes, 13 repeat orchidopexies, 17 'vanishing testis syndrome' and seven atrophic testes. The remaining 486 undescended testes were treated using a standard orchidopexy and were therefore excluded from analysis. CONCLUSION: The value and advantages of this operative approach and its place in the management strategy of the difficult orchidopexy are discussed.