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

The RXFP2-PLC/PKC signaling pathway mediates INSL3-induced regulation of the proliferation, migration and apoptosis of mouse gubernacular cells

BACKGROUND

Testicular hypoplasia can affect the sexual and reproductive ability in adulthood, and even increase the risk of cancer. Abnormal development of the gubernaculum is one of the important factors of testicular hypoplasia. Therefore, a study of the structure and function of the gubernaculum is an important but neglected new breakthrough point for investigating the normal/abnormal development of the testis. Previous findings showed that Insulin like factor 3 (INSL3) is a key factor regulating the growth of gubernaculum, however, the mechanism by which INSL3 acts on the gubernaculum remains unknown. Therefore, we probed the mechanism associated with INSL3-induced the proliferation, migration, and apoptosis of gubernacular cells in mice.

METHODS

A culture cell model of neonatal mice gubernaculum is established by INSL3 intervention. We blocked PLC/PKC signaling pathway with U73122 pretreat to investigate the role of the PLC/PKC signaling pathway. The changes of cell proliferation, migration, and apoptosis were detected by molecular biological methods. In addition, the levels of PCNA and F-action were detected by immunofluorescence and western blotting.

RESULTS

We found that INSL3 can promote the proliferation and migration of gubernacular cells and inhibit their apoptosis, meanwhile, INSL3 significantly up-regulated PLC/PKC protein phosphorylation. However, treatment with the PLC/PKC signaling pathway inhibitor U73122 significantly inhibited these effects of INSL3. Besides, we found that INSL3 could up-regulate the protein expression level of PCNA and F-actin, while the PCNA and F-actin expression was significantly weakened after U73122 pretreatment.

CONCLUSIONS

This research revealed that INSL3 binding to RXFP2 may up-regulate the expression levels of PCNA and F-actin by activating the PLC/PKC signaling pathway to promote the proliferation and migration of gubernacular cells. It suggests that the RXFP2-PLC/PKC axis may serve as a novel molecular mechanism by which INSL3 regulates growth of the gubernaculum.

Gubernaculum and Epididymo-Testicular Descent: Review of the Literature

Cryptorchidism is a common disorder in boys that has been widely studied both experimentally and clinically. The role of the gubernaculum, a mesenchymal tissue extending from the fetal testis and epididymis to the developing scrotum, is still unclear. Even the name is debated: 'gubernaculum epididymis' or 'gubernaculum testis'. This review does not aim to provide a global overview of competing theories on testicular descent, but focuses on the role of the gubernaculum in epididymo-testicular descent. We identified four major pitfalls of gubernaculum research: the role of the gubernaculum, of insulin-like peptide 3, anti-Müllerian hormone, and androgens. The major critical issues were that the gubernaculum plays a guiding role for the epididymis, descending prior to the testis and expanding the inguinal canal; insulin-like peptide 3 is not as important for the process of descent in humans as the rate of insulin-like peptide 3 mutations is low; anti-Müllerian hormone plays no significant role in epididymo-testicular descent; androgens and gonadotropins play a crucial role in epididymo-testicular descent. The role of the epididymis in the complex process of gubernaculum, epididymis, and testis migration is underestimated and should be included in future research.

Effects of the prenatal environment on cryptorchidism: A narrative review

Cryptorchidism, the absence of testes from the scrotum, is the most common genital disorder in boys and a risk factor for reduced fertility and testicular cancer. The mechanism responsible for cryptorchidism involves two discrete stages: a transabdominal and an inguinoscrotal phase. These phases of testicular descent are regulated by the prenatal sex hormone environment, including levels of testosterone, insulin-like factor 3, and calcitonin gene-related peptide. Environmental endocrine disruptors, which are unfavorable environmental factors, may also affect testicular descent through prenatal sex hormones. This review examined the effects of environmental factors, particularly environmental endocrine disruptors, such as phthalates, organochlorine pesticides, diethylstilbestrol, bisphenol A, dioxins/dioxin-like compounds, and perfluoroalkyl substances, and parental lifestyles on the risk of cryptorchidism. Although some studies have shown that environmental endocrine disruptors can affect testicular descent by changing the hormonal environment during the prenatal period, no significant association has been established between exposure to environmental endocrine disruptors and the incidence of cryptorchidism. Therefore, the role played by environmental endocrine disruptor exposure (if any) in the pathogenesis of cryptorchidism remains unknown. Further studies are needed to examine these issues.

Testicular arteries anatomy applied to fowler-sthephens surgery in high undescended testis - a narrative review

Objectives:

In this review we will describe the testicular vessels anatomy and the implications of these vessels in surgical treatment of high undescended testis.

Material and Methods:

We performed a narrative review of the literature about the role of the testicular arteries anatomy in the treatment of high undescended testis. We also studied two human testes to illustrate the testicular vascularization.

Results:

Each testis is irrigated by three arteries: testicular artery (internal spermatic artery), a branch of the right aorta; deferential artery (vasal artery), a branch of the inferior vesicle artery that originates from the anterior trunk of internal iliac artery and cremasteric artery (external spermatic artery), a branch of the inferior epigastric artery. There are important communications among the three arteries with visible anastomotic channels between the testicular and deferential arteries.

Conclusions:

Laparoscopic transection of the testicular vessels by dividing the spermatic vessels (Fowler-Stephens surgery) is safe in patients with high abdominal testis due to the great collateral vascular supply between testicular, vasal and cremasteric arteries; also, two-stage Fowler-Stephens orchiopexy appears to carry a higher rate of success than the single stage approach.

Effect of the occupational environment of parents on cryptorchidism

BACKGROUND

The early detection and treatment of cryptorchidism are necessary to preserve male fertility. This study aimed to assess the effect of parents' occupational environment on the incidence of cryptorchidism in their sons.

METHODS

The study enrolled 51 316 newborn males, whose mothers were recruited in the Japan Environment and Children's Study. We analyzed cryptorchidism incidence in male newborns according to 14 categories of occupation of their parents. We also analyzed the effect of the mother's occupational environment during gestation, including working and night-shift work, on cryptorchidism incidence. Information on occupations was obtained from self-administered questionnaires. Cryptorchidism was identified through a survey at birth or 1 month after birth using medical records.

RESULTS

Cryptorchidism was identified in 305 male infants (0.59%) at birth or 1 month after birth. Weight, height, head circumference, and chest circumference at birth were significantly lower in male infants with cryptorchidism than in those without the condition. Gestational age was also shorter in mothers whose infants developed cryptorchidism. Moreover, maternal age at delivery and smoking during gestation also had an effect on cryptorchidism incidence. However, multivariate analysis of the 14 categories of occupation of parents during gestation showed no significant effect on cryptorchidism incidence in their male infants.

CONCLUSIONS

This study revealed that the work environment of parents did not significantly affect the incidence of cryptorchidism in their sons. However, this study might have underestimated mild and transient cases of cryptorchidism. Further studies are necessary to investigate the risk factors of cryptorchidism in relation to parents' occupation.

Structural and functional significance of scrotal ligament: a comparative histological study

Gubernaculum testes is the most important parameter in testicular migration. At the end of migration, it is described as scrotal ligament, which has implications in testicular torsion. The present study aims to examine the structure of scrotal ligament and compare it with gubernaculum. Sixteen adult cadaveric testicular specimens and fourteen fetal testicular specimens of different age groups were examined after getting ethical clearance from the institute ethics committee and consent from the parents. Meticulous dissection was done. The length, site of proximal, and distal attachment of scrotal ligament and gubernaculum were noted and histologically evaluated. A separate scrotal ligament could not be delineated in any adult specimens. It merged with testicular coverings. Histological examination showed the presence of patchy areas of dense collagen fibres of variable density amidst loose areolar connective tissue. In contrast, fetal specimens showed the presence of a definitive gubernaculum testes and revealed the presence of mesenchymal tissue, collagen, elastic fibres, and myocytes which varied according to gestational age of fetuses. Structure of scrotal ligament and gubernaculum testes is highly variable. Description of scrotal ligament as a firm attachment from lower pole of testes to scrotum is controversial, questioning its role as protective factor in testicular torsion.

Interplay between collagenase and undescended testes in Adamts16 knockout rats

BACKGROUND

The inguinoscrotal stage of testicular descent is characterized by an increase in cell density and collagen fibers as the gubernaculum undergoes cell division and increases Extracellular Matrix (ECM) activity. Rats that lack the enzyme Adamts16, a known ECM proteinase, develop cryptorchidism postnatally and are infertile. Therefore, this study aims to investigate the link between the Adamts16 enzyme and congenital undescended testes (UDT) in Adamts16 knockout (KO) rats during postnatal development.

METHODS

Formalin-fixed specimens of Wild-Type, Adamts16 heterozygous and Adamts16 homozygous KO rats post birth were sectioned and used for standard H&E histology and Masson's trichrome staining. A quantitative analysis on image J was performed to determine the intensity of collagen fibers within the inguinoscrotal fat pad (IFP) (n = 3 age/genotype).

RESULTS

The migration of the gubernaculum within the Adamts16 heterozygous and Adamts16 KO rat was considerably disrupted. Furthermore, the Masson's trichrome staining demonstrated a significant increase in collagen fibers around the gubernaculum of rats that lacked Adamts16 enzyme at day 8.

CONCLUSION

This study reports a failure of gubernacular migration leading to UDT in Adamts16 KO rats during development, suggesting that the expression of Adamts16 gene is critical for normal gubernacular migration through the breakdown of collagen fibers within the IFP.

Clinically Differentiated Abnormalities of the Architecture and Expression of Myosin Isoforms of the Human Cremaster Muscle in Cryptorchidism and Retractile Testis

AIM

To describe architecture and expression of myosin isoforms of the human cremaster muscle (CM) and to individuate changes in clinically differentiated abnormalities of testicular descent: cryptorchidism or undescended testis (UDT) and retractile testis (RT).

BACKGROUND

The CM is a nonsomitic striated muscle differentiating from mesenchyme of the gubernaculum testis. Morphofunctional and molecular peculiarities linked to its unique embryological origin are not yet completely defined. Its role in abnormalities of testicular descent is being investigated.

SUBJECTS AND METHODS

Biopsy samples were obtained from corrective surgery in cases of cryptorchidism, retractile testis, inguinal hernia, or hydrocele. Muscle specimens were processed for morphology, histochemistry, and immunohistology.

RESULTS AND CONCLUSIONS

The CM differs from the skeletal muscles both for morphological and molecular characteristics. The presence of fascicles with different characterization and its myosinic pattern suggested that the CM could be included in the specialized muscle groups, such as the extrinsic ocular muscles (EOMs) and laryngeal and masticatory muscles. The embryological origin from the nonsomitic mesoderm is, also for the CM, the basis of distinct molecular pathways. In UDT, the histological alterations of CM are suggestive of denervation; the genitofemoral nerve and its molecular messengers directed to this muscle are likely defective. Compared with the other samples, RT has a distinct myosinic pattern; therefore, it has been considered a well-defined entity with respect to the other testicular descent abnormalities.

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.

RXFP2 as novel potential biomarker for abnormal differentiation induced by diethylstilbestrol in the gubernaculum of fetal mice

Environmental estrogens (EEs) have been correlated with abnormalities in the male urogenital system. However, the mechanism underlying the effect of these molecules remains unclear. In vitro and in vivo experiments were performed to examine the expression level and mechanism of relaxin family peptide receptor 2 (RXFP2) in the gubernaculum of fetal mice following diethylstilbestrol (DES) treatment. The in vivo results demonstrate that DES treatment increased the stillbirth rate gradually, decreased the gubernacular cone volume significantly, and disrupted the tissue structure, leading to incomplete testicular descent. In vitro experiments reveal that DES administration resulted in abnormal cellular morphology and structural disorder of gubernacular cells, which lost their original morphology in a dose-dependent manner. Moreover, DES-induced F-actin rearrangement and stress fiber formation in cultured cells. Protein quantitative analysis showed that the RXFP2 level in each experimental group was significantly lower than that of the normal group. In conclusion, DES affects the morphology and alters the gubernaculum structure, as well as the expression of RXFP2 protein. These data demonstrate that DES is toxic to gubernaculum in fetal mice, and that RXFP2 is associated with the abnormal gubernaculum morphology induced by DES. Taken together, these data suggest that RXFP2 may be a novel potential biomarker for abnormal differentiation of the gubernaculum.

Is Testicular Germ Cell Cancer Estrogen Dependent? The Role of Endocrine Disrupting Chemicals

Testicular germ cell cancer (TGCC) is the most frequent cancer of the young male, with an increasing incidence worldwide. The pathogenesis and reasons for this increase remain unknown. However, epidemiological and experimental data have suggested that, similar to genital malformations and sperm impairment, it could result from the interaction of genetic and environmental factors including fetal exposure to endocrine-disrupting chemicals (EDCs) with estrogenic effects. In this review, we analyze the expression of classic and nonclassic estrogen receptors by TGCC cells, the way they may influence germ cell proliferation induced by EDCs, and discuss how this estrogen dependency supports the developmental and environmental hypothesis.

Late ascended testes: is non-orthotopic gubernacular insertion a confirmation of an alternative embryological etiology?

INTRODUCTION

Re-ascended testes account for a proportion of all undescended testes (UDTs); one main hypothesis relating to their etiology relates to a patent processus vaginalis peritonei. The aim was to investigate gubernacular insertion points in boys with late ascended testis as a possible guide to an alternative embryological etiology.

PATIENTS AND METHODS

Patients with proven ascended testes were recruited from four different pediatric urology centers between May 2016 and September 2017. All patients were evaluated regarding their gubernacular insertion during orchidopexy. The presence of accompanying patent processus vaginalis and the association between the epididymis and testis were also documented.

RESULTS

Seventy-seven children (mean age = 73.1 ± 41.2 months [range 18-176]) were enrolled into the study. A non-orthotopic gubernacular insertion point was found in 96.1% (n = 74); 34.2% (n = 26) of these were located in the groin and 63.2% (n = 48), high within the scrotum. Figure A. An open processus vaginalis peritonei was found in 35.1%. Twelve patients (15.6%) had small, dysplastic appearing testis with testis-epididymis dissociation. Boys with a higher insertion of the non-orthotopic gubernaculum (n = 48, groin) were operated earlier (mean age at surgery, 62.3 months) compared with those with a gubernacular insertion at a high scrotal site (mean age at surgery, 90.5 months; p = 0.004). Figure B.

DISCUSSION

This study revealed that non-orthotopic gubernacular insertion is found in the vast majority of the ascending testis cases. Patent processus vaginalis was accompanying only 35.1% of all children and might be the cause of the ascending testis in this small subgroup of patients in line with the earlier reports [1]. In boys with ascending testes, in this population, the gubernaculum was very likely to insert non-orthotopically. In concordance with previous reports [2] and regarding the finding of a an earlier age at surgery in boys with higher inserting gubernacula, this could provide a logical explanation as to how these testes are initially palpable in the scrotum and then, during body growth are retracted to the groin.

CONCLUSION

In 96.1% of the patients, a non-orthotopic gubernacular insertion was found. This points to embryologic etiology, complying well with earlier reports and further underlining the critical importance of timely diagnosis and treatment for this group of patients.

Impaired male fertility and abnormal epididymal epithelium differentiation in mice lacking CRISP1 and CRISP4

Epididymal Cysteine Rich Secretory Proteins 1 and 4 (CRISP1 and CRISP4) associate with sperm during maturation and play different roles in fertilization. However, males lacking each of these molecules individually are fertile, suggesting compensatory mechanisms between these homologous proteins. Based on this, in the present work, we generated double CRISP1/CRISP4 knockout (DKO) mice and examined their reproductive phenotype. Our data showed that the simultaneous lack of the two epididymal proteins results in clear fertility defects. Interestingly, whereas most of the animals exhibited specific sperm fertilizing ability defects supportive of the role of CRISP proteins in fertilization, one third of the males showed an unexpected epididymo-orchitis phenotype with altered levels of inflammatory molecules and non-viable sperm in the epididymis. Further analysis showed that DKO mice exhibited an immature epididymal epithelium and abnormal luminal pH, supporting these defects as likely responsible for the different phenotypes observed. These observations reveal that CRISP proteins are relevant for epididymal epithelium differentiation and male fertility, contributing to a better understanding of the fine-tuning mechanisms underlying sperm maturation and immunotolerance in the epididymis with clear implications for human epididymal physiology and pathology.

Anatomy and histology of the scrotal ligament in adults: inconsistency and variability of the gubernaculum testis

PURPOSE

The anatomy of gubernaculum testis (GT) is often discussed; however, the postnatal anatomy of the GT or scrotal ligament (SL) is rarely described. Hence, we performed an anatomical and histological study to analyze histologically the structures between testis and scrotum.

METHODS

We performed anatomical dissections on 25 human fresh cadavers' testes. Each testis was removed with its envelopes and macroscopically analyzed. Then samples were included for histological study. Finally, they were analyzed under microscope, looking for attachments between testis, epididymis and scrotal envelopes.

RESULTS

The absence of proximal and distal attachment was found in 56.0% of cases. Looking at the proximal attachment of the SL, the main one found is the epididymal attachment (28.0%), whereas no cases of testis attachment was found. Distally, there are more variations with scrotal attachment (12%) and cremaster attachment (12.0%). We found a significant prevalence of multiple adherences in 16.0% of cases too. Finally, in 15 cases (57.7%) an attachment is present between testis and epididymis, as it is commonly described.

CONCLUSIONS

In the majority of cases there is no attachment of the lower pole of the testis and epididymis and these structures remain free. So it seems that the SL disappears with aging. Moreover, there is not only one kind of ligamentous attachment, but a high variability of attachments at the lower pole of the testiculo-epididymal structure. When it exists, this structure is never a real ligament and it seems more appropriate to use the term "attachments".

Persistent Mullerian Duct Syndrome: a rare entity with a rare presentation in need of multidisciplinary management

Main findings:

A typical male looking adolescent with a legal female gender assignment presented with haematuria. Investigations led to the diagnosis of Persistent Mullerian Duct Syndrome. The condition is indeed a rare entity that needs a multidisciplinary team management.

Case hypothesis:

A case of Persistent Mullerian Duct Syndrome undiagnosed at birth because karyotyping was defaulted, thus resulting in a significant impact on the legal gender assignment and psychosocial aspects.

Promising future implications:

The reporting of this case is important to create awareness due to its rarity coupled with the rare presentation with hematuria as a possible masquerade to menstruation. There were not only medical implications, but also psychosocial and legal connotations requiring a holistic multidisciplinary management.

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.

An inguinal hernia with cryptorchidism with a Leydig cell tumor in an elderly man: A case report

INTRODUCTION

Cryptorchidism is common in children but is rare in the elderly. It often presents with a constellation of signs and symptoms similar to routine inguinal hernias. We present the case of an elderly man with cryptorchidism containing a Leydig cell tumor and provide clinical insights.

PRESENTATION OF CASE

An-84-year old man was admitted with an incarcerated right lower quadrant hernia. Both testes were absent on palpation of the scrotum. After reduction of the hernia, computed tomography scan revealed a round lesion in the hernia sac, which was suspected to be the ectopic testis. Laparoscopic exploration was performed in combination with an open anterior approach. The hernia orifice was the right internal inguinal ring, and the inguinal canal was obliterated by adhesions because the spermatic cord did not pass through it. The ectopic testis was resected with the hernia sac, and the hernia repaired with a KUGEL™ patch (Bard, USA).

DISCUSSION

Laparoscopic exploration was useful to delineate the anatomy of this unusual inguinal hernia. The open anterior approach was necessary to dissect the ectopic testis and the hernia sac. Pathological findings revealed tumor cells with clear cytoplasm in the resected testis, diagnosed as a Leydig cell tumor.

CONCLUSION

The combination of laparoscopic and anterior approaches facilitated the surgical treatment of an unusual inguinal hernia with cryptorchidism. The resected ectopic testis should undergo thorough histopathologic examination.