The genitofemoral nerve may link testicular inguinoscrotal descent with congenital inguinal hernia

A comparative study of smooth muscle cell characteristics and myofibroblasts in processus vaginalis of pediatric inguinal hernia, hydrocele and undescended testis

BACKGROUND

Congenital inguinal hernia, hydrocele and undescended testis (UDT) are associated with patent processus vaginalis. The smooth muscles present in the processus vaginalis aid in the descent of the testis and undergo programmed cell death after testicular descent leading to obliteration. The persisting amount of smooth muscle in the processus vaginalis influences the clinical outcome as inguinal hernia, hydrocele or UDT. Therefore, a study was conducted to evaluate the processus vaginalis in these three conditions to observe the presence and phenotype of smooth muscle cells and the presence of myofibroblasts.

MATERIALS AND METHODS

The processus vaginalis sacs in patients with inguinal hernia, hydrocele and UDT were examined using light microscopy for the presence and distribution of smooth muscle cells and immunohistochemical staining for vimentin, desmin, and α-smooth muscle actin (SMA) to identify the smooth muscle phenotype. Transmission electron microscopy was also performed in all the sacs to observe the presence of myofibroblasts.

RESULTS

Seventy-eight specimens of processus vaginalis (from seventy-four patients), distributed as 47%, 27%, and 26% as inguinal hernia, hydrocele and UDT respectively, were included in the study. The sacs from inguinal hernia and hydrocele had significantly more presence of smooth muscles distributed as multiple smooth muscle bundles (p < 0.001). Desmin and SMA staining of smooth muscle cells was observed in significantly more sacs from hydrocele, followed by inguinal hernia and UDT (p < 0.001). The sacs from UDT had a significant presence of striated muscles (p = 0.028). The sacs from inguinal hernia had a significant presence of myofibroblasts, followed by hydrocele and UDT (p < 0.001) and this significantly correlated with the light microscopy and immunohistochemical features. The processus vaginalis sacs from four female patients did not differ statistically from the male inguinal hernia sacs in any of the above parameters.

CONCLUSION

The processus vaginalis sacs in pediatric inguinal hernia, hydrocele and undescended testis differ in the presence, distribution and phenotype of smooth muscles and the presence of myofibroblasts. The clinical presentations in these entities reflect these differences.

Testicular descent: A review of a complex, multistaged process to identify potential hidden causes of UDT

BACKGROUND/PURPOSE

What causes normal descent of the testis in a fetus, and what goes wrong with this complex process to cause undescended testes (UDT), or cryptorchidism? Over the last 2 decades, most authors searching for the cause(s) of UDT have looked at the 2 main hormones involved, insulin-like hormone 3 (Insl3) and testosterone (T)/ dihydrotestosterone (DHT), and their known upstream (hypothalamic-pituitary axis) and intracellular 'downstream' pathways. Despite these detailed searches, the genetic causes of UDT remain elusive, which suggest the aetiology is multifactorial, and/or we are looking in the wrong place.

METHODS

In this review we highlight the intricate morphological steps involved in testicular descent, which we propose may contain the currently 'idiopathic' causes of UDT. By integrating decades of research, we have underlined many areas that have been overlooked in the search for causes of UDT.

RESULTS

It is quite likely that the common causes of UDT are still hidden in these areas, and we suggest examining these processes is worthwhile in the hope of finding the common genetic anomalies that lead to cryptorchidism. Given the fact that a fibrous barrier preventing descent is often described at orchidopexy, examination of the extracellular matrix enzymes needed to allow gubernacular migration may be a fruitful place to start.

CONCLUSION

This review of the complex anatomical steps and hormonal regulation of testicular descent highlights many areas of morphology and signalling pathways that have been overlooked in the search for causes of UDT.

Laparoscopic surgery: an effective and safe surgical method of pediatric inguinal hernia repair

Purpose

Inguinal hernia (IH) repair is very commonly performed in children. While open repair (OR) is the standard approach, laparoscopic repair is increasingly used. This study was aimed to investigate safety and feasibility of laparoscopic repair of pediatric IH compared to OR.

Methods

We retrospectively enrolled 105 pediatric patients with IH repair between January 2011 and October 2019. The laparoscopic procedures performed were laparoscopic percutaneous extraperitoneal closure (LPEC), and three-port mini-laparoscopic repair (TLR). The OR was performed as per usual technique.

Results

Thirty-nine patients underwent OR, 16 LPEC, and 50 TLR. The preoperative laterality of IH was 45 patients (42.9%) on the right side, 50 (47.6%) on the left side, and 10 (9.5%) on both sides. It was, however, diagnosed postoperatively in 27 patients (25.7%) on the right side, 38 (36.2%) on the left side, and 40 (38.1%) on both sides. Of the 63 patients who presented with unilateral IH in the laparoscopic groups, 32 (50.8%) had synchronous contralateral patent process vaginalis (PPV) which were simultaneously repaired. This was significantly more common in children under 3 years of age. Operative time in unilateral or bilateral repair was significantly shorter in the laparoscopic repair groups (p < 0.001). Ipsilateral recurrence was not observed in any group. Metachronous contralateral IH occurrence was not significantly different between groups.

Conclusion

Laparoscopic IH repair may have benefit in terms of shorter operation time and diagnosis of unpredicted contralateral PPV compared to OR.

The role of intra-abdominal pressure in human testicular migration

Objectives:

This review aims to study the role of the abdominal wall in testicular migration process during the human fetal period.

Materials and Methods:

We performed a descriptive review of the literature about the role of the abdominal wall in testicular migration during the human fetal period.

Results:

The rise in intra-abdominal pressure is a supporting factor for testicular migration. This process has two phases: the abdominal and the inguinal-scrotal stages. The passage of the testis through the inguinal canal occurs very quickly between 21 and 25 WPC. Bilateral cryptorchidism in Prune Belly syndrome is explained by the impaired contraction of the muscles of the abdominal wall; mechanical obstruction due to bladder distention and structural alteration of the inguinal canal, which hampers the passage of the testis during the inguinoscrotal stage of testicular migration. Abdominal wall defects as gastroschisis and omphaloceles are associated with undescended testes in around 30 to 40% of the cases.

Conclusions:

Abdominal pressure wound is an auxiliary force in testicular migration. Patients with abdominal wall defects are associated with undescendend testis in more than 30% of the cases probably due to mechanical factors; the Prune Belly Syndrome has anatomical changes in the anterior abdominal wall that hinder the increase of intra-abdominal pressure which could be the cause of cryptorchidism in this syndrome.

Inguinoscrotal stage of testicular descent: analysis in 217 human fetuses

BACKGROUND

Testicular descent is a complex process of relevant importance for the comprehension of cryptorchidism. Studies about the inguinoscrotal stage of testicular migration correlating the testicular position with fetal parameters are rare in the literature. Our hypothesis is that the transition of the testis by the inguinal canal is a very fast process and occurs at the end of the third gestational trimester.

AIM

To analyze the inguinoscrotal stage of testicular descent during the human fetal period.

STUDY DESIGN

This is an observational study in human fetuses. We studied 217 human male fetuses ranging from 10 to 35 weeks postconception (WPC). The fetuses were well preserved and evaluated regarding crown-rump length (CRL) and body weight before dissection. Testicular position was classified as: a) abdominal, when the testis was proximal to the internal ring; b) inguinal, when it was found between the internal and external inguinal rings; and c) scrotal, when being inside the scrotum. Means were statistically compared using the unpaired t-test (P < 0.05).

RESULTS

Of the 434 testes, 329 (75.8%) were abdominal, 48 (11.05%) were inguinal, and 57 (13.13%) were scrotal. The first case of inguinal testis was observed in a fetus with 17 WPC, 203 g, and 15 cm CRL. The 48 inguinal testes were observed in 29 fetuses (13.36%), aged between 17 and 29 WPC, weighing between 203 and 1220 g, and with CRL between 15 and 27.5 cm. Of the 29 fetuses with inguinal testes, 23 (79.32%) were aged between 20 and 26 WPC; 3 (10.34%) had 17 WPC; and 3 (10.34%) had more than 26 WPC. All the fetuses with more than 30 WPC had testes in the scrotum. We did not observe fetuses less than 17 WPC with the testes in the canal.

DISCUSSION

We found that all fetuses with more than 30 WPC had the testes located in the scrotum and that in fetuses between 17 WPC and 25 WPC, 38 testes (8.7% of the sample) were situated in the canal and only 1 testis in a fetus with 25 WPC was located in the scrotum, showing that the second stage of testicular migration through the inguinal canal rarely occurs before the 20th WPC.

CONCLUSION

The inguinoscrotal stage of testicular descent is a fast process, observed only in 13% of the fetuses and occurring with more intensity between 20 and 26 WPC.

Persistence of the processus vaginalis and its related disorders

The processus vaginalis is a blind-ended evagination of the abdominal wall that develops during fetal life and typically undergoes obliteration in early life. Persistence of the processus vaginalis is associated with a number of pathologies including congenital indirect inguinal hernias, communicating hydroceles, funicular and encysted hydroceles, canal of Nuck cysts, and acquired undescended testis. Whilst all are detectable sonographically, there is little educational material relevant to the field of ultrasound with much of the literature directed at surgical and primary care physicians. Furthermore, within the literature there is a lack of consensus on several areas including the anatomy and embryology of the processus vaginalis and the mechanisms behind its obliteration. As such the objective of this paper is to distil the information regarding the persistent processus vaginalis as it is relevant to ultrasound and in doing so address the literature gap for sonographers and sonologists. The anatomy and embryology of the persistent processus vaginalis will be discussed including causative mechanisms for anomalies with their sonographic appearance highlighted.

Do prune-belly syndrome and neural tube defects change testicular growth? A study on human fetuses

BACKGROUND

There are no reports comparing testicular volume between normal fetuses, fetuses with prune-belly syndrome (PBS), and fetuses with anencephaly. The study hypothesis was that PBS and especially anencephaly alter the testicular volume during the human fetal period.

AIM

The objective of the study was to compare the testicular growth in fetuses with anencephaly, with PBS, and without anomalies.

STUDY DESIGN

This is a morphometric study of human fetuses. Seventy testes from fetuses without anomalies aged 11-22 weeks post-conception (WPC), 30 testes from fetuses with anencephaly aged 13-19 WPC, and eight testes from fetuses with PBS aged 13-16 WPC were studied. Testicular length, width, and thickness were evaluated with the aid of computer programs (Image Pro and ImageJ) (Figure). The fetal testicular volume was calculated using the ellipsoid formula: Testicular volume (TV) = [length × thickness × width] × 0.523. The Shapiro-Wilk test was used to ascertain the normality of the data and to compare quantitative data between normal fetuses vs. fetuses with anencephaly, while the Kruskal-Wallis test was used to assess gender and laterality differences. Simple linear correlations (LCs) were calculated for testicular volume according to fetal age, weight, and crown-rump length.

RESULTS

All 108 testes studied were abdominal. The right (p = 0.0310) and left (0.0470) testicular volumes were significantly smaller in fetuses with anencephaly than those in the control group. The linear regression analysis indicated that the right and the left testis volume in the control group (right: r² = 0.6665; left: r² = 0.6707) and PBS group (right: r² = 0.9937; left: r² = 0.9757) increased with fetal age (p < 0.0001). This analysis also indicated that the testicular volume in fetuses with anencephaly did not increase with fetal age (right: r² = 009816; left: r² = 0.07643).

DISCUSSION

This article is the first to report testicular volume correlations with fetal parameters in fetuses with anencephalic and fetuses with PBS. Significant alterations were observed in testicular growth in the anencephalic group compared with the control group, and it was also observed that the bilateral cryptorchidism in PBS does not alter the testicular development and growth during the fetal period. The unequal WPC distribution between fetuses with PBS, fetuses with anencephaly, and controls and the small sample size are limitations of this study. Further studies should be performed to confirm this study's findings.

CONCLUSIONS

Testicular growth is slower and does not show significant correlations with fetal parameters in fetuses with anencephalic. Significant differences in testicular development in fetuses with PBS was not observed.

An immunohistochemical analysis of the effects of androgen receptor knock out on gubernacular differentiation in the mouse

AIM

Cryptorchidism affects 2%-4% of newborn boys and causes infertility and cancer. While normal androgen function is required for successful inguinoscrotal descent, its exact role on gubernacular morphology remains unidentified. We aimed to decipher the effect of androgen blockade on the gubernaculum and surrounding structures.

METHODS

Genetically modified mice with androgen receptor knock out (ARKO) were sectioned at ages E17, D0, and D2 for immunohistochemical analysis and D4 for morphological analysis (with ethical approval; A644). Mutants and control littermates were labeled with Ki67, Desmin, and Pax7 to identify the degree of gubernaculuar eversion and the composition of the growth center in the gubernaculum, using light or confocal microscopy.

RESULTS

Androgen blockade prevented gubernacular eversion in all animals aged between E17 and D2 when compared to wild types. Furthermore, a growth center was visible, as indicated by a 'swirl' of immature fibroblasts, in D2 animals but was absent in ARKO mice. Moreover, the gubernacular cord was seen to increase in ARKO mice when compared to wild types and increased in size with age. There were no labeling differences in the antibodies tested for gubernacular differentiation.

CONCLUSION

Gubernacular eversion in rodents prior to inguinoscrotal migration was androgen dependent, as well as maintenance of gubernacular cord length. This study shows that androgen blockade causes cryptorchidism in mice by preventing gubernacular eversion and possibly by preventing shortening of the gubernacular cord. Altering the morphology of the gubernaculum in response to androgen clearly contributes to the clinical problem of cryptorchidism.

Structural study of the cremaster muscle in patients with retractile testis

OBJECTIVE

To analyze the structure of the cremaster in patients with retractile testis (RT), comparing the distribution of nerves, elastic system and muscles with patients having cryptorchidism and inguinal hernia (IH).

PATIENTS AND METHODS

We studied 31 patients, 17 with RT (mean age=5.17years); 9 with IH (mean age=2.6) and 5 with cryptorchidism (mean age=3). A cremaster biopsy was performed and submitted to routine histological processing and studied using histochemistry and immunohistochemistry. The samples were photographed under an Olympus BX51 microscope. The images were processed with the Image J software and the cremaster muscle structures were quantified. Means were compared statistically using ANOVA and the unpaired t-test (p<0.05).

RESULTS

There were no differences (p=0.08) in diameter of muscle fiber between the groups. The muscle fiber density differed between patients with RT and IH (p=0.02): RT (mean=17.71%, SD=16.67), IH (mean=38.06%, SD=14) and cryptorchidism (mean=21.47%, SD=16.18). There was no difference (p=0.07) in the density of elastic fibers in the three groups. We observed a lower concentration of cremaster nerves of patients with RT compared with IH (p=0.0362): RT (mean=1.72%, SD=0.58), IH (mean=3.28% SD=0.94) and cryptorchidism (mean=2.52%, SD=0.53).

CONCLUSIONS

Retractile testis is not a normal variant, and presented a similar cremaster muscle structure as in patients with cryptorchidism.

LEVEL OF EVIDENCE

II; prospective comparative study.

Is there a trans-abdominal testicular descent during the second gestational trimester? Study in human fetuses between 13 and 23 weeks post conception

OBJECTIVES

To confirm if a real inner descend of testis occurs, correlating the testicular position with fetal parameters and analyzing the position of the testes relative to the internal ring.

MATERIAL AND METHODS

Twenty nine human fetuses between 13 and 23 weeks post conception (WPC) were studied. The fetuses were carefully dissected with the aid of a stereoscopic lens with 16/25X magnification and testicular position observed. With the aid of a digital pachymeter the distance between the lower pole of the kidney and the upper extremity of the testis (DK-T) was measured to show the position of the testis. During the dissection we also indicated the position of the testes relative to the internal ring. Means were statistically compared using simple linear regression and the paired T-test.

RESULTS

The 58 testes had abdominal position. The DK-T in the right side measured between 0.17 and 1.82cm (mean=0.79cm) and in the left side it was between 0.12 and 1.84cm (mean=0.87cm), without statistically differences (p=0.0557). The linear regression analysis indicated that DK-T in both sides correlated significantly and positively with fetal age. All fetuses with more than 20 WPC, heavier than 350g and with CRL over 22cm had a greater distance than the average DK-T. We xobserved that the 58 testis remains adjacent to the internal ring throughout the period studied.

CONCLUSIONS

The testes remains adjacent to the internal ring throughout the period studied, indicating that there is no real trans-abdominal testicular descent during the second gestational trimester.

Neurotrophin signaling in a genitofemoral nerve target organ during testicular descent in mice

BACKGROUND/AIM

It has been proposed that androgens control inguinoscrotal testicular descent via release of calcitonin gene-related peptide (CGRP) from a masculinised genitofemoral nerve (GFN). As there are androgen receptors in the inguinoscrotal fat pad (IFP) during the window of androgen sensitivity (E14-17 in mouse embryos), we tested the hypothesis that neurotrophins in the IFP may masculinise the sensory fibers of the GFN supplying the gubernaculum and IFP prior to gubernacular migration.

METHODS

Androgen-receptor knockout (ARKO) and wild-type (WT) mouse embryos were collected at E17, with ethical approval (AEC 734). Sagittal sections of IFP, mammary area and bulbocavernosus (BC) muscle were processed for standard histology and fluorescent immunohistochemistry for ciliary neurotrophic factor (CNTF), ciliary neurotrophic factor receptor (CNTFR) and cell nuclei (DAPI).

RESULTS

In the ARKO mouse CNTFR immunoreactivity (CNTFR-IR) was increased in the IFP but decreased in BC. Perinuclear staining of CNTF-IR was seen in mouse sciatic nerve but only weakly in IFP. In the mammary area, also supplied by GFN, there were no differences in IR staining.

CONCLUSION

This study found CNTFR-IR in the IFP was negatively regulated by androgen, suggesting that CNTF signaling may be suppressed in GFN sensory nerves to enable CGRP expression for regulating gubernacular migration in the male, but not the female. The indirect action of androgen via the GFN required for testicular descent may be one of the sites of anomalies in the putative multifactorial cause of cryptorchidism.

The importance of the gubernaculum in testicular migration during the human fetal period

OBJECTIVES

The objective of this review is to study the role of the gubernaculum in the testicular migration process during the human fetal period.

MATERIALS AND METHODS

We performed a descriptive review of the literature about the role of the gubernaculum in testicular migration during the human fetal period.

RESULTS

In the first phase of testicular migration, the gubernaculum enlarges to hold the testis near the groin and in the second phase the gubernaculum migrates across the pubic region to reach the scrotum. The proximal portion of the gubernaculum is attached to the testis and epididymis and the presence of multiple insertions in the distal gubernaculum is extremely rare. The presence of muscle and nerves in the human gubernaculum is very poor. The gubernaculum of patients with cryptorchidism has more fibrous tissue and less collagen and when the patients are submitted to hormonal treatment, the gubernaculum components alter significantly.

CONCLUSIONS

The gubernaculum presents significant structural modifications during testicular migration in human fetuses.

Regulation of testicular descent

Testicular descent occurs in two morphologically distinct phases, each under different hormonal control from the testis itself. The first phase occurs between 8 and 15 weeks when insulin-like hormone 3 (Insl3) from the Leydig cells stimulates the gubernaculum to swell, thereby anchoring the testis near the future inguinal canal as the foetus grows. Testosterone causes regression of the cranial suspensory ligament to augment the transabdominal phase. The second, or inguinoscrotal phase, occurs between 25 and 35 weeks, when the gubernaculum bulges out of the external ring and migrates to the scrotum, all under control of testosterone. However, androgen acts mostly indirectly via the genitofemoral nerve (GFN), which produces calcitonin gene-related peptide (CGRP) to control the direction of migration. In animal models the androgen receptors are in the inguinoscrotal fat pad, which probably produces a neurotrophin to masculinise the GFN sensory fibres that regulate gubernacular migration. There is little direct evidence that this same process occurs in humans, but CGRP can regulate closure of the processus vaginalis in inguinal hernia, confirming that the GFN probably mediates human testicular descent by a similar mechanism as seen in rodent models. Despite increased understanding about normal testicular descent, the common causes of cryptorchidism remain elusive.

Testicular migration chronology: do the right and the left testes migrate at the same time? Analysis of 164 human fetuses

OBJECTIVE

To determine if the right and the left testes migrate at the same time during the human fetal period.

SUBJECTS AND METHODS

We studied 164 human fetuses (328 testes) ranging in age from 12 to 35 weeks post-conception. The fetuses were carefully dissected with the aid of a stereoscopic lens at ×16/25. The abdomen and pelvis were opened to identify and expose the urogenital organs. Testicular position was classified as: (a) Abdominal, when the testis was proximal to the internal ring; (b) Inguinal, when it was found between the internal and external inguinal rings); and (c) Scrotal, when it was inside the scrotum.

RESULTS

The testes were abdominal in 71% of the cases, inguinal in 9.41%, and scrotal in 19.81%. There was asymmetry in testicular migration in nine cases (5.5%). In three of these nine cases, one testis was situated in the abdomen and the other in the inguinal canal; in another three one testis was situated in the abdomen and the other in the scrotum, and in the remaining three, one testis was in the inguinal canal and the other in the scrotum. In five of the nine cases of asymmetry, the right testis completed the migration first, but this was not statistically significant.

CONCLUSION

Asymmetry in testicular migration is a rare event, accounting for <6% of the cases. The right testis seems to complete migration first.

One third of patients with a unilateral palpable undescended testis have a contralateral patent processus

PURPOSE

The purpose of this study was to determine the incidence and predictive factors associated with a contralateral patent processus vaginalis in boys with a unilateral palpable undescended testis.

METHODS

We retrospectively reviewed the records of 77 consecutive boys (median age, 15 months; range, 5 months to 17.7 years) who had undergone orchiopexy for a unilateral palpable testis. At inguinal orchiopexy, an 8F feeding tube and a 70° adult cystoscope lens were placed into the peritoneum through the hernia sac, and the contralateral internal ring was inspected. The clinical factors that might predict the presence of a contralateral patent processus vaginalis were determined.

RESULTS

The overall rate of a contralateral patent processus vaginalis was 34% in those with a significant ipsilateral hernia sac. After considering age, side, prematurity, location, and volume of the undescended testis, only the boys with a testis distal to the external ring compared with those with testes lying within the inguinal canal had statistically increased odds of a patent contralateral processus vaginalis (odds ratio, 3.1; 95% confidence interval, 1.08-9.08).

CONCLUSION

Approximately one third of boys with a unilateral palpable undescended testis will have a contralateral patent processus vaginalis as determined by transinguinal laparoscopy. The rate is higher (52%) if the undescended testis was distal to the external ring. Both the etiology and significance of this contralateral finding are unknown.

Embryology of the testicular descent

Numerous researchers studied the morphology of the testicular descent, including the possible function of the gubernaculum. However, a clear illustration of this process is still missing. The aim of this paper was to illustrate the embryology of the testicular descent in the rat by scanning electron microscopy. In a first phase of the intra-abdominal testicular descent, the testis moves actively from the lower pole of the kidney towards the bladder neck. In a second inguinal phase the testis enters groin and moves in the developing processus vaginalis peritonei caused by the disappearance of the bulb of the gubernaculums testis.

Inguinal hernia: aetiology, diagnosis, post-repair pain and compensation

BACKGROUND

Inguinal hernia compensation depends on aetiology, diagnosis and complications, particularly post-hernia pain. New studies in these three areas bring confusion to claims.

METHODS

A comprehensive research of the literature using Medline: in aetiology, in diagnoses, the use of ultrasound and/or other investigations, in chronic post-hernia pain and the understanding of the pathogenesis of hernia and post-hernia pain. Using the above data, a creation of a protocol for acceptance of compensation claim.

RESULTS

Although intra-abdominal pressure has been accepted for 200 years as a significant aetiological factor in inguinal hernia, tissue studies and prospective studies suggest an inevitability. In diagnosis, the clinical detection of a lump is the gold standard; investigations are not required. An ultrasonic detection of a hernia without clinical correlation does not require surgery. Post-hernia chronic pain is not singular to hernia, is now considered neuropathic pain and treatment is conservative.

CONCLUSIONS

The work scene is possibly an aggravating factor but not a prime aetiological factor. The diagnosis does not require ultrasound. Chronic pain is neuropathic. A protocol for claim acceptance is presented.

Cryptorchidism

Cryptorchidism is a very common anomaly of the male genitalia, affecting 2%-4% of male infants and is more common in premature infants. There are two separate stages of testicular descent. The first stage occurs at 8-15 weeks' gestation in the human fetus and is characterized by enlargement of the genito-inguinal ligament, or gubernaculum, and regression of the cranial suspensory ligament. The testis remains close to the future inguinal region as the fetal abdomen grows. Leydig cells in the testis produce insulin-like hormone 3, which stimulates the caudal gubernaculum to grow and become thicker. Mullerian inhibiting substance may have a role in the first phase of descent by stimulating the swelling reaction in the gubernaculum. The second phase of testicular descent requires migration of the gubernaculum and testis from the inguinal region to the scrotum, between 25 and 35 weeks' gestation. The genitofemoral nerve releases calcitonin gene-related peptide, a neurotransmitter that provides a chemotactic gradient to guide migration. The exact cause of cyrptorchidism remains elusive. Information is mainly derived from animal studies (especially in rodents), which may not extrapolate to the human setting. These findings, however, do have some similarities among mammalian species. The current recommended timing for orchidopexy is between 6 and 12 months of life in an effort to preserve the spermatogonia--the stem cells for subsequent spermatogenesis. Despite surgical treatment by orchidopexy, the long-term outcome still remains problematic and controversial. Impaired fertility (33% in unilateral cases and 66% in bilateral undescended testes) and a cancer risk 5-10 times greater than normal is observed over time. Further research into the cause and management of undescended testes is necessary.

The testicular descent in the rat: a scanning electron microscopic study

PURPOSE

Numerous researchers studied the morphology of testicular descent including the possible function of gubernaculum. However, a clear illustration of this process is still missing. The aim of this study was to illustrate testicular descent using scanning electron microscopy (SEM) in a rat model.

METHODS

The abdomen of rat fetuses between gestational day (E) 15 and E 22 and newborns at postnatal day (D) 0 and D 1.5 was opened by microsurgery. Standard preparation for SEM was carried out. The position of the testis and gubernaculum testis was documented.

RESULTS

The gubernaculum was obvious in male rat embryos at E 17.5. In a first phase (E 16-E 21) the testis moved from cranio-lateral and dorsal to caudo-medial and ventral, while clear signs of an active role of the gubernaculum were missing. In a second phase (E 22-D 1.5) the processus vaginalis peritonei (PVP) developed, while the conus of the gubernaculum disappeared, after which, the testis moved out of the abdominal cavity and entered the PVP.

CONCLUSION

In our study, we could not specify the role of gubernaculum for testicular descent. However, our data showed that the testis lay intraperitoneal throughout the descensus testis.

Looking past the lump: genetic aspects of inguinal hernia in children

Inguinal hernia is associated with a multitude of genetic syndromes. Disorders of the microfibril, elastin, collagen, and the glycosaminoglycan component of the extracellular matrix can result in an increase in the likelihood of inguinal hernia. In addition, inguinal hernia may be the presenting feature of disorders of sexual differentiation. Inguinal hernia of unknown etiology also occurs more commonly in several other groups of genetic diseases including chromosomal disorders, microdeletion disorders such as 22q11.2 microdeletion, and in single gene disorders. We review the genetics of connective tissue formation and focus on a series of genetic conditions that may present with or are characterized by a higher risk of inguinal hernia. A comprehensive review of the literature aims to provide a diagnostic framework to aid in the identification of patients with inguinal hernia as part of underlying genetic disease.

Analysis of anomalies of the epididymis and processus vaginalis in human fetuses and in patients with cryptorchidism treated and untreated with human chorionic gonadotrophin

OBJECTIVE

To analyse the incidence of epididymal anomalies and the structure of the processus vaginalis (PV) in patients with cryptorchidism treated or not with human chorionic gonadotrophin (hCG), and to compare these findings with human fetuses with testes in the scrotum.

PATIENTS, MATERIALS AND METHODS

We assessed 24 fetuses with a gestational age of 23-35 weeks, and 114 cryptorchid patients (mean age 10.3 years). The patients were divided into two groups of those who used hCG (55, 65 testes) and those who did not (59, 75 testes). The sample was divided into six groups of possible anatomical relationships between the testis and the epididymis, according to a previous classification. Two situations were considered to analyse the PV: (a) total obliteration between the internal inguinal ring and the upper pole of the testis; and (b) total patency.

RESULTS

Epididymal anomalies were found in 35% of patients with cryptorchidism and in only 4% of normal fetuses. Of the 47 cases of epididymal anomalies in patients with cryptorchidism 23 (49%) were treated with hCG and 24 (51%) were not. The PV was patent in 58% of patients with cryptorchidism and in only 5% of fetuses. Considering the three groups, the epididymal anomalies were more frequent when the PV was patent.

CONCLUSIONS

Patency of the PV and the incidence of epididymal anomalies were more frequent in patients with cryptorchidism. The existence of epididymal anomalies did not influence testicular migration in patients treated with hCG.

Relationship between the persistence of the processus vaginalis and age in patients with cryptorchidism

OBJECTIVES

To assess if there is an age group where the occurrence of persistent processus vaginalis is more frequent in patients with cryptorchidism.

MATERIALS AND METHODS

We studied 24 fetuses with gestational age between 23 and 35 weeks postconception (control group) and 102 patients (137 testes) with cryptorchidism aged between 1 and 33 years (mean 10.3 years). We considered 2 situations for analysis of the processus vaginalis: a) complete persistence of processus vaginalis and, b) complete obliteration of the processus vaginalis between the internal inguinal ring and the upper pole of the testis.

RESULTS

Of the 137 cases of cryptorchidism, the processus vaginalis was patent in 79 (57.6%) and obliterated in 58 (42.4%). Of the 55 patients between 1 and 4 years old, 37 (67.2%) had a patent processus vaginalis and 18 (32.8%) an obliterated one. Of the 37 patients between 5 and 8 years, 17 (45.9%) had patent processus vaginalis and 20 (54.1%) had an obliterated process. In the 45 patients over 9 years of age, in 25 (55.5%) the processus vaginalis was patent and in 20 (44.5%) it was obliterated. In the fetuses, we found 4 cases (8.3%) of persistence of the processus vaginalis.

CONCLUSIONS

There was no difference in the occurrence of patent processus vaginalis between the various age ranges under study. Patent processus vaginalis was more frequent in patients with cryptorchidism than in fetuses.

The role of hepatocyte growth factor in the humoral regulation of inguinal hernia closure

BACKGROUND

Calcitonin gene-related peptide (CGRP) is proposed to indirectly cause inguinal hernia closure via hepatocyte growth factor (HGF). Studies have shown that CGRP and HGF cause processus vaginalis (PV) fusion in vitro. We localized the HGF receptor in the PV and tested whether CGRP was responsible for HGF release.

METHOD

Hernial sacs collected from 20 children (15 males, 4 females, 1 XY female) undergoing inguinal hernia repair were immunohistochemically stained for HGF receptor (c-met). Parietal peritoneum was stained for comparison. Hernial sacs from another 16 children (12 males, 4 females), with each sac divided into 4, were cultured, with and without CGRP, for 24 and 48 hours. Hepatocyte growth factor content was then assayed in the culture medium (4/16 children) and tissue extracts (12/16 children), using enzyme-linked immunosorbent assay. Children were aged 1 month to 10 years. Data were analyzed using paired Student t tests.

RESULTS

C-met localized to the PV epithelial surface in 17 of 20 hernial sacs and in the parietal peritoneum. Hepatocyte growth factor levels increased over time in 4 of 4 culture medium assays, with a significant difference in 1 of 4. Seven of 12 tissue extract assays had significant differences; however, 3 of 7 had decreased HGF levels.

CONCLUSION

The presence of HGF receptors in the PV is consistent with a role for HGF in triggering epithelial-mesenchymal transformation during inguinal hernia closure. The presence of HGF receptors in the parietal peritoneum suggests that regulation of this process is complex. Enzyme-linked immunosorbent assay results indicate that, in a subset of patients, exogenous CGRP may be responsible for HGF elevation and potentially implicates deficient endogenous CGRP as one cause for inguinal hernia patency.

Hernias and Ewing's sarcoma family of tumours: a pooled analysis and meta-analysis

BACKGROUND

Ewing's sarcoma family of tumours has been associated with a history of hernia and with a parental occupation of farming. However, the causes of these tumours remain unknown. We therefore aimed to investigate the association between hernia and Ewing's sarcoma family of tumours.

METHODS

We did a pooled analysis of two case-control studies and a meta-analysis of three case-control studies of Ewing's sarcoma family of tumours that had adequate information on history of hernia. The primary endpoint was development of a tumour from the Ewing's sarcoma family. 138 patients with such a tumour and 574 controls were included in the pooled analysis, and 357 patients with these tumours and 745 controls were included in the meta-analysis. Risk was assessed by an odds ratio (OR) and 95% CI by use of multivariate analysis with unconditional logistic regression for the pooled analysis and random effects model for the meta-analysis.

FINDINGS

Pooled analysis showed that children with Ewing's sarcoma family of tumours were more likely to have had an umbilical hernia than were controls (odds ratio [OR] 3.3 [95% CI 1.3-8.0]). Meta-analysis showed that children with Ewing's sarcoma family of tumours were more likely to have had a hernia (3.2 [1.9-5.7]).

INTERPRETATION

Ewing's sarcoma family of tumours and hernias (particularly inguinal hernias) have common embryological pathways of neuroectodermal origin, and environmental factors, such as farming, might link the two entities.

Could inguinal hernia be treated medically?

Inguinal hernia is the most common congenital anomaly requiring surgical correction. The cause of the hernia is, most commonly, persistence of the processus vaginalis. Study of testicular descent in rodents has revealed a role for the genitofemoral nerve and calcitonin gene-related peptide (CGRP). Since the testis cannot descend without the processus vaginalis, we wondered whether both descent and hernia closure might be regulated by the same mechanism. Therefore, we tested the idea that CGRP might be active in closure of the inguinal hernia. Using hernial sacs removed at herniotomy operation, fusion of the hernial surfaces was induced by CGRP, but not by CGRP 8-37, CGRP 27-37 or dihydrotestosterone. Hepatocyte growth factor also caused peritoneal obliteration in vitro. We propose that obliteration of the processus vaginalis is under the control of molecules released from the genitofemoral nerve, and that a chemical treatment of inguinal hernia is at least theoretically possible.

Scrotal ultrasonography with emphasis on the extratesticular space: anatomy, embryology, and pathology

Sonography is the imaging modality of choice in detecting and characterizing pathologic conditions affecting the extratesticular space. Although most abnormalities are benign, many may simulate or represent malignant processes. Accurate diagnosis is therefore essential and must be based not only on the sonographic findings but also on accurate clinical history and physical examination findings. This article reviews the anatomy, embryologic development, and pathologic conditions affecting the extratesticular space.

The development of the gubernaculum and inguinal closure in the marsupial Macropus eugenii

This study reports the developmental anatomy of testicular descent and inguinal closure of the tammar wallaby (Macropus eugenii) from birth to maturity. In females the ovary migrated caudally between days 10 and 20 after birth. The gubernaculum differentiates into the round ligament in the abdomen and extra-abdominally as the ilio-marsupialis muscle of the mammary glands. In males the testes migrated to the internal inguinal ring by day 20 post partum (pp), coinciding with the enlargement of the gubernaculum, and from the internal inguinal ring to the scrotum between days 20 and 65 pp. During descent there was an increase in the hyaluronic acid concentration in cells of the gubernaculum and scrotum. Development of the cremaster muscle began by day 10 pp on the periphery of the gubernaculum and its basic structure was completed by day 60 pp. After descent the inguinal canal closed between days 50 and 60 pp, but a small irregular lumen persisted, somewhat similar to that seen in the congenital scrotal hydrocoele of humans. Tammars have a hopping mode of locomotion and, like humans, are essentially bipedal. We suggest that inguinal closure evolved in these two species because their upright posture may otherwise lead to a high incidence of inguinal hernias.

Maternal, delivery, and perinatal characteristics associated with cryptorchidism: a population-based case-control study among births in Washington State

BACKGROUND

The etiology of cryptorchidism is largely unknown. To identify maternal, perinatal, and delivery characteristics associated with cryptorchidism at birth, we conducted a population-based case-control study using Washington State birth certificates linked to birth hospitalization records.

METHODS

We identified 2,395 cases of cryptorchidism among male infants born in Washington State during 1986-1996, and, for comparison, we randomly selected four controls per case (N = 9,580), frequency-matched by year of birth.

RESULTS

Infant characteristics associated with cryptorchidism included low birth weight (OR = 1.5; 95% CI = 1.3-1.8), small size for gestational age (OR = 1.9; 95% CI = 1.6-2.2), and breech presentation (OR = 1.7; 95% CI = 1.4-2.1). In addition to cryptorchidism, cases were more likely to have another type of congenital malformation (OR = 3.7; 95% CI = 3.2-4.2), particularly digestive (OR = 6.8; 95% CI = 3.7-12.7) or genitourinary (OR = 4.1; 95% CI = 3.0-5.6). Maternal and pregnancy characteristics associated with cryptorchidism included nulliparity (OR = 1.2; 95% CI = 1.1-1.3), maternal smoking during pregnancy (OR = 1.2; 95% CI = 1.1-1.4), and the following pregnancy complications: oligohydramnios (OR = 1.8; 95% CI = 1.3-2.6), placental abnormality (OR = 1.3; 95% CI = 1.0-1.8), and pregnancy-induced hypertension (OR = 1.6; 95% CI = 1.4-1.9). Odds ratios were similar when the analysis was restricted to term infants.

CONCLUSIONS

These findings suggest that factors affecting fetal growth and development may increase the risk of cryptorchidism.

Inguinal hernia in patients with Ewing sarcoma: a clue to etiology

BACKGROUND

Various congenital anomalies have been associated with childhood cancer, but as yet no anomaly has been consistently found with Ewing sarcoma (ES). Recently a large case-control study of ES patients reported a greater number of hernias in both cases and their sibling controls than in population controls. Most of these hernias were inguinal. Because these anomalies were also reported previously in two case series, we looked for inguinal hernias in a different population of ES patients.

PROCEDURE

We abstracted medical records for 306 pathologically confirmed ES/primitive neuroectodermal tumor (PNET) patients seen at NIH between 1960 and 1992. Epidemiological data on demographics and medical conditions were analyzed. The frequency of anomalies was compared to expected rates to calculate relative risk and confidence intervals.

RESULTS

Anomalies were present in 67 (22%) cases. A particular anomaly, inguinal hernia, was reported for 13 (5%) NIH cases. Compared to population estimates for white children, the relative risk of inguinal hernia among white NIH cases was 13.3 (95% CI 3.60-34.1) for females and 6.67 (95% CI 2.67-13.7) for males.

CONCLUSIONS

The findings of inguinal hernias in some patients with ES suggest that a disruption in normal embryological development occurred. This may provide an important clue to the etiology of ES. We hypothesize that these hernias may relate to an in utero exposure or indicate an underlying genetic disorder. Future studies should carefully evaluate ES families for genetic disease and explore environmental factors. Med. Pediatr. Oncol. 34:195-199, 2000. Published 2000 Wiley-Liss, Inc.

Cremaster muscles obtained from boys with an undescended testis show significant neurological changes

OBJECTIVE

To compare cremaster muscles (CMs) obtained from boys with inguinal hernia, hydrocele or an undescended testis and those obtained from girls with inguinal hernia, thus defining the changes associated with each clinical condition.

MATERIALS AND METHODS

CM samples were obtained from 26 boys and three girls with inguinal hernia, and 18 boys who had undergone surgery for an undescended testis (12) or hydrocele (six). The samples were frozen in isopentane cooled in liquid nitrogen and were processed for sectioning by cryostat. Sections (12 microm) were stained with a several histochemical stains. The presence of central nuclei, fibre splitting, basophilic fibres, fibre necrosis, inflammatory changes, small angular fibres, fibre hypertrophy, grouped atrophy, and endo- and perimysial fibrosis were evaluated. From each specimen, 200 fibres were also analysed morphometrically using a computerized image analysis system.

RESULTS

Neurogenic changes were apparent in all the CMs from patients with an undescended testis but none of the samples obtained from girls showed any changes. While only two specimens of 26 from boys with inguinal hernia (8%) had evidence of neurological alterations, eight CM (31%) had general changes. The mean (SD) fibre diameters did not differ significantly among the groups with inguinal hernia, hydrocele and undescended testis, at 23. 0 (8.6), 24.4 (4.5) and 23.0 (10.5) microm, respectively.

CONCLUSION

Cremasteric muscles associated with an inguinal hernia or an undescended testis differ; neurogenic changes were detected within all the CM of boys with an undescended testis. These changes in the CM may have influenced the location of the testis.

Lack of carbachol response indicates the absence of cholinergic receptors in sacs associated with undescended testis

BACKGROUND/PURPOSE

The mechanism of testicular descent remains controversial. The processus vaginalis (PV) contains smooth muscle and should have contractile activity that may contribute to descent. This study was designed to evaluate the smooth muscle of PVs associated with incomplete obliteration for spontaneous activities and responses to various stimuli, to determine if differences exist according to sex, diagnostic source, or location of the testis.

MATERIALS

Peritoneal samples (n = 4); sacs from girls (n = 8) and boys with inguinal hernia (n = 12); and sacs from boys with hydrocele (n = 3), hydrocele of the cord (n = 2), or undescended testis (n = 7) were used for the current study. Tissues were attached to the isometric force displacement transducer in an organ bath containing mammalian Ringer's solution at 37 degrees C. Spontaneous mechanical activity and contractile responses of tissues to the electrical field stimulation, phenylephrine, carbachol, and serotonin were recorded. The values obtained from boys and girls with inguinal hernia and from boys with either undescended or descended testis were compared through Fisher's Exact test.

RESULTS

There were no statistically significant differences in patient age between groups. Among the parameters studied, only the carbachol response of the sacs associated with undescended testis showed a significant difference compared with the others (P = .001). None of the sacs associated with undescended testis responded to carbachol, whereas all of the sacs from boys and girls with inguinal hernia responded to carbachol.

CONCLUSIONS

Lack of carbachol response suggests the absence of cholinergic receptors within the sacs associated with undescended testis. The lack of cholinergic receptors may play a role in the failure of the process of testicular descent by hindering either PV elongation into the scrotum or a possible propulsive activity of the PV on the testis.

Ovary in hernia sac: prolapsed or a descended gonad?

BACKGROUND/PURPOSE

The ligament that lies in the inguinal hernia sac of girls is known to be the round ligament and is described as homologous to the male gubernaculum. An ovary in a hernia sac might be assumed to mimic descent of the testis. The aim of this study is to determine whether this ligament has a role in final ovarian position.

METHODS

Samples of peritoneal tissues containing the ligament were obtained from 15 female infants and children who underwent inguinal hernia repair. Tissue specimens were evaluated through histopathologic and immunohistological analyses.

RESULTS

The ligament consists of striated and smooth muscle fibers, abundant nerves, and vessels. Estrogen receptors (ER) and progesterone receptors (PR) were identified in submesothelial stromal and smooth muscle cells. No androgen receptors (AR) were found.

CONCLUSIONS

Although its termination in the processus vaginalis is not found to be consistent with the classical description of the round ligament, localization of ERs and PRs prove that the ligament is a target organ influenced by hormones. Because the round ligament is supposed to be the female gubernaculum that has an altered anatomy and localization because of absence of androgen responsiveness, its modified presentation in a processus vaginalis raises the suspicion that the ovary in a hernia sac may not simply be prolapsed, but is a descended gonad.

Etiology and pathophysiology of primary and recurrent groin hernia formation

The cause of primary groin hernia is multifactorial with evolutionary, hereditary, congenital, environmental aspects, and the general state of health all playing their part. Besides maintaining general body fitness and not smoking tobacco, there is little one can do to avoid this common affliction. On the other hand, recurrent groin hernia is largely due to easily controllable human factors and can be avoided by choosing an experienced surgeon with a particular interest and understanding of the subject, preferably one who specializes in and confines himself to the surgery of groin hernias, working in a unit dedicated to herniology he will select the best operation for the particular type of hernia and execute it to conform to the highest acceptable standards, using the best materials and techniques. The patient will rapidly, within a matter of days, return to his full, normal activities and can look forward to a success rate of over 99%.

Contractility and electrophysiological parameters of cremaster muscles of boys with a hernia or undescended testis

BACKGROUND/PURPOSE

The cremaster muscle (CM) has been considered to participate in regulation of blood flow and temperature of the testis. Its contribution to testicular descent has been suggested. However, there is limited information about the CM in physiological and pathological states. Therefore, an experimental study has been conducted to evaluate and compare the contractile and electrophysiological properties of CM in boys with descended or undescended testes.

METHODS

Identical CM strips were obtained from eight boys who underwent orchidopexy with a mean age of 3+/-2.2 years and from eight boys who underwent herniorrhaphy with a mean age of 4+/-1.3 years. Muscle strips of 3 x 8 mm were vertically attached to an isometric force displacement transducer, and direct muscle contractions were elicited by rectangular electrical pulses. Direct isometric muscle contractions were recorded in an organ bath containing mammalian Ringer's solution. In electrophysiological experiments, conventional microelectrode techniques were used.

RESULTS

Direct electrical stimulation of CM strips obtained from patients with descended and undescended testes elicited muscle twitches and frequency-dependent contractile responses. Tetanic contractions of undescended testes at 100 Hz were 67% greater in amplitude than that of descended testes (P< .002). Muscle strips of both groups exhibited increased twitch amplitudes by 105%+/-37% when the temperature of the bathing solution was increased from 22 degrees to 37 degrees C (P< .001). The electrophysiological findings were similar.

CONCLUSIONS

Contrary to other striated muscles, elevated temperature increases the contractility of CM. If the increased contractility by an increase in temperature is a property unique for CM, it should reflect the attempts at regulating testicular blood flow or temperature. The increased amplitude of contractions encountered among the CM of boys with undescended testis suggests the CM to have a role on the location of the testis.