Pediatric Urology: Review Article

Abdominal testicular vessel distribution in human fetuses - basis for fowler-Stephens surgery

PURPOSE

To analyze the histology and distribution of abdominal testicular vessels in human fetuses Patients and Methods: We studied 19 fetuses (34 testes) ranging in age from 12 to 19 weeks post-conception. The fetuses were evaluated regarding crown-rump length (CRL), total length (TL) and body weight immediately before dissection. Each testis was dissected and embedded in paraffin, from which 5 μm thick sections were obtained and stained with Masson's trichrome and Anti-CD31 antibody to quantify the vessels. The stereological analysis was carried out with the Image Pro and Image J programs, using a grid to determine volumetric densities (Vv). Means were statistically compared using the unpaired T-test (p<0.05).

RESULTS

The fetuses presented mean weight of 222.5g, mean CRL of 15.3 cm and mean TL of 23.2 cm. All testes were in the abdominal position. The mean percentage of vessels (Vv) in the upper portion of the testis was 7.6% (4.6 to 15%) and in the lower portion the mean was 5.11% (2.3 to 9.8%), with a significant difference (p=0.0001). In the analysis between the upper portion of the right and left testes (p=0.99) and in the analysis of the lower portion of the right and left testes (p=0.83), we did not observe significant differences.

CONCLUSION

The upper portion of the abdominal testis in human fetuses had a higher concentration of vessels than the lower portion. These results suggest that manipulation of the lower end of the testis during Fowler-Stephens surgery should be avoided in order to preserve the collateral circulation.

Testicular descent revisited: a micro-computed tomography study in fetal rats

PURPOSE

There is a long history of research dealing with the embryology of the testicular descent. However, important aspects like the role of the gubernaculum and the development of the processus vaginalis peritonei are not understood. Micro-computed tomography (µCT) is an established tool for anatomical studies in rodents. Our study applied µCT imaging to visualize the testicular descent in rats and focused on the role of the gubernacular bulb and the development of the processus vaginalis peritonei.

METHODS

Rats from embryonic day 15 (ED15) to ED21 and newborns (N0) were fixed and dried using the "critical point" technique. We ran a SkyScan^® µCT system and scans were analyzed for gender-specific differentiation of the genital ridge and used for 3D visualization of relevant anatomic structures.

RESULTS

µCT imaging confirmed the intraperitoneal location of the testicles from ED15 to N0. The components of the inner genital moved closer together while the intestinal volume expanded. The gubernacular bulb seemed to be involved in the formation of the processus vaginalis peritonei.

CONCLUSION

Here, we utilized µCT imaging to visualize the testicular descent in the rat. Imaging provides new morphologic aspects on the development of the processus vaginalis peritonei.

The curious case of testicular descent: factors controlling testicular descent with a note on cryptorchidism

Background

The testicular descent is a uniquely complex process depending upon multiple factors like growth and reorganisation of the specific gonadal ligaments, hormones, etc., which interplay with each other. Though an unambiguous event, it is still laced with incredulity since the data interpretation were intermingled between different species creating more ambiguity in certain aspects of this process. In order to understand the aetiopathology of cryptorchidism the extensive study of the factors controlling the descent is necessitous.

Main body

Though testes originate in the abdomen, they migrate to an extra abdominal site the scrotum, which makes it vulnerable to pathological conditions associated with the descent. The hormones that play vital role in the first phase of descent are insulin-like hormone 3 (INSL3), Anti-müllerian hormone as well as testosterone, whereas androgens, genitofemoral nerve and its neurotransmitter calcitonin gene-related peptide (CGRP) influence the second phase. Despite the vast research regarding the complex nexus of events involving the descent there are disparities among the cross species studies. However all these discrepancies make testicular descent yet again fascinating and perplexing. Our aim is to provide a comprehensive review including recent advances which provides thorough coverage of anatomical and hormonal factors in the descent as well as cryptorchidism.

Conclusion

Though our understanding on testicular descent has evolved over the decades there still has obscurity surrounding it and the studies on the factors responsible for descent are becoming more intense with the time. Our knowledge on many factors such as INSL3 and CGRP is more established now; however, on the other hand the role of androgens still remains speculative. As the knowledge and understanding of the biological process of testicular descent increases it will pave ways to new treatment plans to treat cryptorchidism more effectively.

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.

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.

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.

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.

Five different cases of ectopic testes in children: a self-experience with literature review

Background

Empty scrotum may be due to many reasons; besides true undescended testis these are monorchia, retractile testis, atrophy of testis due to torsion and ectopic testis. The location of testis in an aberrant site after passing through the inguinal canal and leaving it via external ring is a condition called ectopic testis. The most common aberrant locations of ectopic testes are superficial inguinal pouch (Denis Browne pouch), within anterior abdominal wall, perineum, femoral canal, contralateral scrotum (transverse testicular ectopia) and prepenile area.

Methods

Description of management of five different cases of ectopic testes over a period of 10 years’ experience in pediatric surgery have been done with review of the literature about this rarity.

Results

Five different cases of ectopic testes were as follows: infants 3 months of age with right ectopic testis in anterior abdominal wall near anterior superior iliac spine, 4 months of age with left perineal testis, 6 months of age with an ectopic femoral testis on left side, 8 months of age with transverse testicular ectopia on left side and 10 months of age with right true undescended testis and left perineal testis.

Conclusions

Search for ectopic sites of testes should always be in mind during examination of patients with empty scrotum. Early surgical repair of ectopic testes is recommended, as there is no chance of spontaneous correction to the normal location. Long-term follow-up is necessary due to relatively high incidence of infertility and malignant transformation. Surgeons should be aware of the rare possibility of transverse testicular ectopia in cases of inguinal hernia with impalpable testis on the contralateral side.

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.

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.

Relationship between Undescended Testis Position and Prevalence of Testicular Appendices, Epididymal Anomalies, and Patency of Processus Vaginalis

Objectives

To assess the incidence of testicular appendices (Tas), epididymal anomalies (EAs), and processus vaginalis (PV) patency in patients with undescended testis (UT) according to testicular position and to compare them with human fetuses.

Methods

We studied 85 patients (108 testes) with cryptorchidism and compared the features with those of 15 fetuses (30 testes) with scrotal testes. We analyzed the relationships among the testis and epididymis, patency of PV, and the presence of TAs. We used the Chi-square test for statistical analysis (p < 0.05).

Results

In 108 UT, 72 (66.66%) had PV patent, 67 (62.03%) had TAs, and 39 (36.12%) had EAs. Of the 108 UT, 14 were abdominal (12.96%; 14 had PV patency, 9 TAs, and 7 EAs); 81 were inguinal (75%; 52 had PV patency, 45 TAs, and 31 EAs), and 13 were suprascrotal (12.03%; 6 had PV patency, 13 TAs, and 1 EAs). The patency of PV was more frequently associated with EAs (p = 0.00364). The EAs had a higher prevalence in UT compared with fetuses (p = 0.0005).

Conclusions

Undescended testis has a higher risk of anatomical anomalies and the testes situated in abdomen and inguinal canal have a higher risk of presenting patency of PV and EAs.

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.

The pediatric inguinal canal: Systematic review of the embryology and surface anatomy

The inguinoscrotal region is one of the most common areas operated on in pediatric surgery. Despite this, the surface anatomy of the pediatric inguinal canal is variably defined. The aim of the current systematic review is to evaluate the development and surface anatomy of the pediatric inguinal canal. A systematic review of inguinal canal anatomy in children was conducted using the electronic databases: Medline, PubMed, Scopus, and Google Scholar. Relevant anatomical measurements and relationships were reviewed. The anatomical structures forming the walls of the inguinal canal were identified in fetuses as early as 8-10 weeks gestation. No studies addressed the developmental basis of this early defect in the lower anterior abdominal. Later gonadal development and descent has a defined role. In vivo measurements of children carried out during open surgery are inconsistent. Some studies showed rapid growth velocity of the length of the inguinal canal up to 2 years of age (with height and growth of the bony pelvis) before plateauing, while others suggested no increase in canal length prior to 10 years of age. The position of the deep inguinal ring was equally unclear; some studies suggested this was medial to the midpoint of the inguinal ligament. No studies described the position of the superficial ring, challenging the assumption that the rings are superimposed in the neonate. The dearth of studies analyzing pediatric inguinal anatomy means that changes in the position of the rings with respect to the lengthening of the canal remain unclear.

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.

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.

Aquaporin water channels in the canine gubernaculum testis

The jelly-like gubernaculum testis (GT) is a hydrated structure consisting of a concentric sheath of dense connective tissue around a loose mesenchymal core, with two cords of skeletal muscle cells asymmetrically placed alongside. Expansion of the GT occurs during the transabdominal phase of testicular descent, linked to cell proliferation together with modifications of the hydric content of the organ. The aim of this study was to detect immunohistochemically the presence of aquaporins (AQPs), integral membrane proteins permitting passive transcellular water movement, in the canine GTs. Samples (n=15) were obtained from pregnancies of 9 medium sized bitches and dissected from healthy fetuses. Five fetuses were aged 35-45 days of gestation, 10 fetuses from 46 days of gestation to delivery, thus offering us the opportunity to study the progressive maturation of the gubernacula. The presence of AQP3, 4, 7, 8 and -9 was assessed in the muscular components of the GT, some of them (AQP3, AQP4, AQP7) with increasing intensity through the second half of pregnancy up to term. AQP1 was localized in the capillary and venous endothelia in the younger fetuses, also in the artery adventitia and in the nerve perineurium in progressively older fetuses. These data demonstrate the potential importance and contribution of AQP-mediated water flux in hydration and volume modification of the growing GT in a canine model.

Left-sided cryptorchidism in mice with Wilms' tumour 1 gene deletion in gubernaculum testis

A significant number of patients with germline mutations in the Wilms' tumour 1 (WT1) gene, a transcriptional factor essential for early renal and gonadal development, display cryptorchidism or non-scrotal testis position. We show here that WT1 is expressed during development in the mouse gubernacular ligament connecting the testis to the abdominal wall. Conditional inactivation of Wt1 in the gubernaculum (GU-WT1KO animals) resulted in abnormal differentiation of the gubernacula during development and, in about 40% of adult males, unilateral, always left-sided, cryptorchidism. At birth the right testis was positioned above the processus vaginalis and eventually moved into the developing scrotal pouch. In affected mutants the left testis was displaced from the normal position and the left processus vaginalis failed to form. The analysis of testicular descent at different stages of postnatal development suggests that unilateral cryptorchidism might be caused by asymmetry in the positions of the abdominal organs providing a higher degree of mobility for the left testis. Spermatogenesis in GU-WT1KO animals was blocked in cryptorchid testes located in a high pararenal position, but was maintained in testes located in a low abdominal position. Conditional inactivation of both Wt1 and androgen receptor (Ar) genes in the gubernaculum led to a bilateral asymmetrical cryptorchidism in all mutant males, with the left testis again located higher than the right one. The malformations induced by WT1 and AR deficiency in the gubernaculum and processus vaginalis, in combination with mechanical constraints on testis descent, determine the final position of the testes. In summary, our data indicate that WT1 is directly involved in gubernaculum differentiation. Taken together, the results of the study underline the complex nature of testicular descent, with an involvement in this process of several genetic factors and developmental events.

Expression of estrogen receptors α and β in paratesticular tissues in boys operated on for unilateral cryptorchidism between the 1st and 4th years of life

BACKGROUND

The aim of this study was to assess the expression of estrogen receptors alpha and beta in paratesticular tissues in a group of boys with and without cryptorchidism, and evaluation of karyotypes, localization, morphology and the major length of the undescended testes.

MATERIAL/METHODS

Fifty boys (1-4 years old) with unilateral cryptorchidism were evaluated. Fifty healthy boys within the same age range, with inguinal hernia, served as a control group. Measurements concerning expression of ERalpha ERbeta receptors were preformed using monoclonal mouse antibodies against human receptor alpha and beta.

RESULTS

In the mesothelial layer, the expression of ERalpha was higher in the patients group with undescended testes and it was statistically significant (p=0.04). There was no difference in the expression of ERbeta in this layer between groups. In the stromal cell layer there was statistically significant higher expression of ERbeta (p<0.05) in the group of patients with undescended testes.

CONCLUSIONS

There was no difference between expressions of ERalpha in stromal cell layer. In the endothelial layer there was no difference in expression of ERalpha and ERbeta. In the smooth muscle layer there was no expression of ERalpha in either group. The expression of ERbeta in the smooth muscle layer was nearly identical in both groups. Undescended testes were generally found in the superficial inguinal pouch (n=46). The major lengths of the undescended testes were smaller in comparison to the testes positioned normally. In 9 of the cases the testes had different shape, and turgor deficit, and epididymides were smaller, dysplastic and separated from the testis.

Effects of perinatal exposure to low doses of tributyltin chloride on pregnancy outcome and postnatal development in mouse offspring

Tributyltin (TBT), an endocrine-disrupting chemical, is well known to induce imposex in female gastropods. In this study, we assessed the effects of low doses of tributyltin chloride (TBTCl) on dams and their offspring. Pregnant mice were administered by gavage with 0, 1, 10, or 100 μg TBTCl/kg body weight/day from day 6 of pregnancy through the period of lactation. There were no TBT treatment-related deaths or clinical signs of toxicity for dams, and no treatment-related effects on body weight, litter sizes, gestational length of dams, and sex ratio, lactational body weight, postnatal survival, age at eruption of incisors, and eye opening of pups. However, at 100 μg/kg, TBTCl retarded the testes descent of male offspring. Behavioral tests showed a significant delay in cliff-drop aversion response in offspring of 10 and 100 μg/kg groups, but no significant difference in the righting reflex between control and TBT-exposed offspring was detectable. These results indicate that neurobehavioral toxicity seems to be one sensitive indicator to assess the risk of low doses of TBT.

Juvenile granulosa cell tumor arising from intra-abdominal testis in newborn: case report and review of the literature

In the present case, the neonate presented with a left-sided abdominal mass and an empty left scrotum. Abdominal ultrasonography showed well-defined cystic formation, and laparotomy revealed a tumor arising from an intra-abdominal left testis. The carcinoembryonic antigen and neuron-specific enolase levels were within normal limits, and the serum β-human chorionic gonadotropin and α-fetoprotein levels were within age-related normal values. The findings from the immunochemistry tests confirmed the diagnosis.

The role of the gubernaculum in the descent and undescent of the testis

Testicular descent to the scrotum involves complex anatomical rearrangements and hormonal regulation. The gubernaculum remains the key structure, undergoing the 'swelling reaction' in the transabdominal phase, and actively migrating out of the abdominal wall to the scrotum in the inguinoscrotal phase. Insulin-like hormone 3 (Insl3) is the primary regulator of the first phase, possibly augmented by Müllerian inhibiting substance/anitmüllerian hormone (MIS/AMH), and regression of the cranial suspensory ligament by testosterone. The inguinoscrotal phase is controlled by androgens acting both directly on the gubernaculum and indirectly via the genitofemoral nerve, and release of calcitonin gene-related peptide from its sensory fibres. Outgrowth of the gubernaculum and elongation to the scrotum has many similarities to an embryonic limb bud.Cryptorchidism occurs because of both failure of migration congenitally, and failure of elongation of the spermatic cord postnatally. Germ cell development postnatally is disturbed in congenital cryptorchidism, but our current understanding of germ cell biology suggests that early orchidopexy, around 6 months of age, should provide a significant improvement in prognosis compared with a previous generation. Hormone treatment is not currently recommended. Acquired cryptorchid testes may need orchidopexy once they no longer reach the scrotum, although this remains controversial.

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.

Suppression of insulin-like3 receptor reveals the role of β-catenin and Notch signaling in gubernaculum development

During male development, the testes move from a high intraabdominal position and descend into the scrotum. The gubernaculum, an inguinoscrotal ligament connecting the testis to the lower abdomen, is believed to play a critical role in this process. The first stage of testicular descent is controlled by insulin like3 hormone (INSL3), produced in testicular Leydig cells. Deletion of Insl3 or its receptor, Rxfp2, in mice causes cryptorchidism. We produced Cre/loxP regulated shRNA transgenic mice targeting RXFP2 expression. We have shown that the transgene was able to reduce Rxfp2 gene expression and thus behaved as a hypomorphic allele of Rxfp2. Variable degrees of uni- and bilateral cryptorchidism was detected in males with the activated shRNA transgene on an Rxfp2+/- background. Conditional suppression of Rxfp2 in the gubernaculum led to cryptorchidism. Gene expression analysis of a mutant cremasteric sac using Illumina microarrays indicated abnormal expression of a significant number of genes in Wnt/β-catenin and Notch pathways. We have demonstrated profound changes in the expression pattern of β-catenin, Notch1, desmin, and androgen receptor (AR), in Rxfp2-/- male embryos, indicating the role of INSL3 in proliferation, differentiation, and survival of specific cellular components of the gubernaculum. We have shown that INSL3/RXFP2 signaling is essential for myogenic differentiation and maintenance of AR-positive cells in the gubernaculum. Males with the deletion of β-catenin or Notch1 in the gubernacular ligament demonstrated abnormal development. Our data indicates that β-catenin and Notch pathways are potential targets of INSL3 signaling during gubernacular development.

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.

Hidden in plain sight: the mammary line in males may be the missing link regulating inguinoscrotal testicular descent

BACKGROUND/PURPOSE

Inguinoscrotal testicular descent is controlled by androgens and the genitofemoral nerve, but the trigger for what makes the gubernaculum become a migratory organ like a limb bud remains unknown. Recent observations in the flutamide-treated rat suggested a link with the mammary line. We aimed, therefore, to reassess histologic anatomy in 2 different rodent models of androgen blockade, the testicular feminisation mouse (TFM) and the flutamide-treated rat.

METHODS

Neonatal TFM mice and fetal and neonatal rats after pretreatment of dams with an antiandrogen, flutamide (75 mg/kg; sunflower oil; days 16-19), were prepared for histologic analysis of the inguinal region and compared with fetal and neonatal controls.

RESULTS

Fetal control rats (E15.5 days) showed a mammary bud just outside the future inguinal canal adjacent to the gubernaculum. Neonatal TFM mice showed persistence of the inguinal breast bud supplied by the genitofemoral nerve. Flutamide-treated rats (D2) showed the gubernaculum surrounded by a persisting breast bud.

CONCLUSIONS

The inguinal mammary line is adjacent to the gubernaculum in fetal rodents, and after androgen blockade, the gubernaculum becomes connected to the breast. The male mammary line, which is hidden in plain sight outside the inguinal canal, is made visible by androgen blockade. It may be the missing link in testicular descent, regulating gubernacular migration.

Mythical 'Tails of Lockwood'

The cause of testicular ectopia has long been a mystery, and over the years, many hypotheses have been suggested to explain the condition. The most famous of these hypotheses is that of the 'Tails of Lockwood'. This developed from a paper written in 1888 by Charles Barrett Lockwood. Although little evidence has ever been found to corroborate this hypothesis, it remains in many textbooks and journal articles to the present day. In the 21st century, this theory should no longer be given as the cause for ectopic testes. Current biological evidence supports a complex process of growth, by elongation and migration of the gubernaculum, rather than a simple mechanical process of testicular descent, as proposed in the 18th century.

Early orchiopexy improves subsequent testicular development and spermatogenesis in the experimental cryptorchid rat model

PURPOSE

The most appropriate period for orchiopexy is controversial. We performed histological analyses of undescended testes to evaluate the influence of orchiopexy timing in an experimental cryptorchid rat model. Furthermore, we extrapolated the timing of orchiopexy in humans from our results.

MATERIALS AND METHODS

Experimental cryptorchid rats were induced with androgen blocker by injecting flutamide into the abdomen of pregnant Sprague-Dawley rats (Chubu Kagaku Shizai, Nagoya, Japan) for 7 days from days 14 to 20 of gestation. Approximately 90% of male newborns had undescended testes and we performed orchiopexy on them 4, 5 and 7 weeks after birth. The testes were removed 10 weeks after birth in all groups, and weight and histological findings were assessed. A modified Johnsen score was used to determine spermatogenesis maturity and germ cell apoptosis was also evaluated.

RESULTS

Nonoperated undescended testes showed atrophic and hypospermatogenesis with germ cell apoptosis, whereas treated undescended testes showed the development of early elongated spermatids. In addition, performing orchiopexy 4 weeks after birth decreased the degeneration of undescended testes compared with that in other groups.

CONCLUSIONS

From the point of view of only testicular development 4-week-old rats reportedly correspond to 1-year-old humans. While we should be cautious when extrapolating our findings to the clinical setting, our current study provides evidence in support of early orchiopexy during the first year of life.

Transverse testicular ectopia: correlation of embryology with laparoscopic findings

Two patients with unilateral transverse testicular ectopia (TTE) without the persistence of Mullerian duct structures are described. Each presented with unilateral impalpable testis and a contralateral inguinal hernia. The diagnosis of unilateral TTE was made during laparoscopic evaluation for undescended testis. The first patient had unilateral TTE on the right side and the second on the left. In both patients, a long thin band resembling the round ligament of the uterus was seen extending from the region of the internal inguinal ring (IIR) on the side of the undescended testis to the opposite inguinal canal. In both patients, there was no patent processus vaginalis on the side of the undescended testis and on the contralateral side the internal rings were widely patent with large hernial sacs. In the second patient, the right vas was seen extending from the right IIR towards the right side of the pelvis. The right vas showed a short segment of discontinuity at the level of the right IIR while its proximal end extended into the left inguinal canal in close relation to the right spermatic vessels. The vasal anomaly was probably ischemic in origin, resulting from excessive mobility of the ectopic testis and its vas in TTE. Correlation of the current hypotheses on the embryology of TTE with the above mentioned laparoscopic findings is discussed.

The migrating gubernaculum grows like a "limb bud"

BACKGROUND

The gubernaculum is crucial for testicular descent, and in the second, or inguinoscrotal, phase of descent it has no caudal attachments. Cranially, it is attached to the testis, but its caudal free tip migrates to the scrotum controlled by the genitofemoral nerve. Recent studies show active proliferation in the tip. We hypothesized that the gubernacular tip may grow like a limb bud.

METHODS

We performed whole-mount in situ hybridization studies on male and female fetal mice (ages, E14.5-E18.5; n = 162) looking for limb bud regulatory factors.

RESULTS

Our results showed that a member of the fibroblast growth factor (Fgf) family, Fgf10, and Hoxa10 were both expressed in the male gubernaculum at E14.5, and Hoxa10 was also expressed in the E16.5 mice. Weak staining was seen in the female gubernaculum for Hoxa10 on days E14.5 and E16.5, whereas no staining for Fgf10 was seen in the female gubernaculums.

CONCLUSIONS

These studies, although preliminary, suggest limb bud regulators are essential for gubernacular growth. Hox genes and Fgfs may be fruitful areas of research to unravel the molecular control of gubernacular migration during testicular descent.

Structural analysis of gubernaculum testis in cryptorchid patients submitted to treatment with human chorionic gonadotrophin

OBJECTIVES

To make a histological and stereological analysis of gubernaculum testis elastic system fibers, collagen and striated muscle cells in patients with cryptorchidism treated with human chorionic gonadotrophin (hCG).

MATERIALS AND METHODS

Gubernacula tissue samples were obtained from 12 patients with cryptorchidism. Patients' ages ranged from 1 to 3 years (mean 1.8). Of the 12 patients, 6 were treated with hCG. The samples were stained with Masson's trichrome to highlight muscle fibers and collagen, and Weigert's resorcin-fuchsin to highlight the elastic system fibers. The volumetric density of these components was determined by stereological methods.

RESULTS

The volumetric density of collagen was increased in patients treated with hCG, ranging from 85.62% to 94.48%, while in patients not submitted to hCG treatment the volume density ranged from 52.12% to 89.46% (p=0.0052). The volumetric density of the elastic system fibers was higher in patients treated with hCG, ranging from 9.62% to 19.62%, while patients not submitted to hCG treatment the volume density of elastic system fibers was between 10.38% and 12.38% (p=0.0030). The volume density of striated muscle fibers in patients treated with hCG ranged from 4.76% to 39.16%, while and in patients not treated hCG it ranged from 3.24% to 11.14% (p=0.0052).

CONCLUSION

Gubernacular components alter significantly when submitted to treatment with hCG. Patients who underwent hCG treatment and had no complete testicular migration had an increase in the concentration of elastic and striated muscle fibers and a decrease in the volumetric density of collagen.

The Undescended Testis

Cryptorchidism represents a common condition affecting male infants that has significant clinical implications, including infertility and testicular malignancy. The precise developmental mechanisms leading to cryptorchidism are poorly understood; however, abnormalities in both functional anatomic and hormonal factors during embryogenesis and testicular descent are implicated. Although surgical intervention is ultimately required, there is a defined role for diagnostic imaging in patient evaluation-particularly in the setting of a nonpalpable undescended testis. Consultation among urologists, pediatric surgeons, and radiologists is paramount to optimize patient care.

Orchidopexy and its impact on fertility

We critically analysed the factors known to influence the fertility potential after orchidopexy in children. A comprehensive literature review of all publications in the English language listed in Medline using the words cryptorchidism, undescended testis, orchidopexy, fertility, semen analysis and surgery from 1970 to 2005. In unilateral ectopic, canalicular and emergent testes, as long as the surgery is carried out in early childhood, fertility outcome is good (>90%). The majority of the bilateral abdominal testes are infertile. While unilateral abdominal testes and unilateral absent or vanishing testes have favourable fertility potential, quantification has proven difficult. Despite multiple studies, fertility in crypt orchid tests is still an uncertain issue. Hormonal treatment in conjunction with early surgical correction has not been fully explored. We recommend orchidopexy soon after 6-7 months of age, corrected for term, to maximise the future fertility potential.

Signalling molecules: clues from development of the limb bud for cryptorchidism?

Recent studies of testicular descent suggest not only that the gubernaculum does not initially attach to the scrotum, but also that it must migrate from the groin. Two findings suggest that the gubernaculum may behave like an embryonic limb bud during this phase. First, the active growth centre is at the distal tip of the gubernaculum. Secondly, the gubernaculum is loose in the subcutaneous tissues beneath Scarpa's fascia. The free protrusion of the gubernaculum from the abdominal wall was so reminiscent of a developing embryonic limb bud, we thought that the biological controls of both processus may be similar. This review examines what is known about vertebrate limb bud development, and compares the mechanisms to what has recently been discovered in the gubernaculum. The hypothesis that both processes may be similar is initially consistent with the current facts, encouraging us to investigate this further experimentally.

Influence for testicular development and histological peculiarity in the testes of flutamide-induced cryptorchid rat model

OBJECTIVES

To investigate influence for the testicular development and to assess the usefulness as an animal model, cryptorchid rats were induced by exposure to flutamide during the fetal period and their testes examined histologically.

METHODS

Flutamide was injected into the abdomen of pregnant rats for 7 days from the 14th to 20th day of gestation. The male offspring in which cryptorchidism was observed at 28 days after birth were defined as the model rats. They were divided into four groups by dosage of flutamide (2.5 mg, 5 mg, 7.5 mg, 15 mg per day), and their testicular weight, spermatogenesis (modified Johnsen score), and germ cell apoptosis were examined histochemically at 10 weeks after birth.

RESULTS

The incidence of cryptorchidism including both unilateral and bilateral in the 2.5, 5, 7.5 and 15-mg flutamide groups was 58.3%, 81.9%, 93.6% and 91.0%, respectively. In the model rats, the undescended testes were located at the caudal end of the abdominal cavity, and these testes weighed less than the contra-descended testes in each group. Histologically, apoptotic cells were markedly increased, the seminiferous tubules were degenerated and disturbance of spermatid differentiation was observed in the undescended testes compared with the normal or contra-lateral descended testes.

CONCLUSIONS

We found out that the incidence of undescended testes increased in a flutamide dose-dependent manner. The findings of histological examination were independent of the administrated dose of flutamide and it is suggested that exposure of the testes to abdominal temperature causes spermatogenic arrest with germ cell apoptosis. The present animal model indicates high incidence of above 90%, has no surgical stress and dose not require special techniques. We believe that the present model is a useful tool for the understanding of pathogenesis and treatment of cryptorchidism and further biological research into spermatogenesis.

Cryptorchidism in common eutherian mammals

Cryptorchidism is failure of one or both testes to descend into the scrotum. Primary fault lies in the testis. We provide a unifying cross-species interpretation of testis descent and urge the use of precise terminology. After differentiation, a testis is relocated to the scrotum in three sequential phases: abdominal translocation, holding a testis near the internal inguinal ring as the abdominal cavity expands away, along with slight downward migration; transinguinal migration, moving a cauda epididymidis and testis through the abdominal wall; and inguinoscrotal migration, moving a s.c. cauda epididymidis and testis to the bottom of the scrotum. The gubernaculum enlarges under stimulation of insulin-like peptide 3, to anchor the testis in place during gradual abdominal translocation. Concurrently, testosterone masculinizes the genitofemoral nerve. Cylindrical downward growth of the peritoneal lining into the gubernaculum forms the vaginal process, cremaster muscle(s) develop within the gubernaculum, and the cranial suspensory ligament regresses (testosterone not obligatory for latter). Transinguinal migration of a testis is rapid, apparently mediated by intra-abdominal pressure. Testosterone is not obligatory for correct inguinoscrotal migration of testes. However, normally testosterone stimulates growth of the vaginal process, secretion of calcitonin gene-related peptide by the genitofemoral nerve to provide directional guidance to the gubernaculum, and then regression of the gubernaculum and constriction of the inguinal canal. Cryptorchidism is more common in companion animals, pigs, or humans (2–12%) than in cattle or sheep (≤1%). Laboratory animals rarely are cryptorchid. In respect to non-scrotal locations, abdominal testes predominate in cats, dogs, and horses. Inguinal testes predominate in rabbits, are common in horses, and occasionally are found in cats and dogs. S.c. testes are found in cattle, cats and dogs, but are most common in humans.

Androgen receptor immunostaining and androgen receptor messenger ribonucleic acid expression are increased in cremaster muscles associated with undescended testis

OBJECTIVES

To determine and compare androgen receptor (AR) immunostaining and AR messenger ribonucleic acid (mRNA) expression in cremaster muscles associated with descended or undescended testis.

METHODS

Eight boys with descended testis but with inguinal hernia and 8 boys with undescended testis were evaluated. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and free testosterone levels were determined, and samples of cremaster muscles were immunostained for AR. Groups were compared by unpaired t tests and Fisher's exact tests; P values of <0.05 were considered significant. Samples of cremaster muscles were obtained from another 5 boys with descended testis but with inguinal hernia and 5 boys with undescended testis. The expression of AR mRNA in those samples was determined by semiquantitative reverse transcriptase polymerase chain reaction.

RESULTS

Serum FSH, LH, testosterone, and free testosterone levels were similar among groups. None of the samples from boys with descended testis showed positive staining, but 4 of 8 samples from boys with undescended testis stained positive for AR. Androgen receptor mRNA transcript levels were approximately 10 times lower in cremaster muscles of boys with descended testis compared with those in boys with undescended testis.

CONCLUSIONS

Despite similar serum hormone levels, more AR expression in cremaster muscles associated with undescended testis might represent evidence of being subjected to a lesser degree of androgenic effects.

Giant unilateral abdominoscrotal hydrocele in association with crossed testicular ectopia

Abdominoscrotal hydrocele and transverse testis ectopia are rare clinical conditions. This case report describes the combination of these two rare entities. An azoospermic and infertile adult man presented with left abdominoscrotal hydrocele and a right impalpable testis. He was treated with left orchiopexy, right orchiectomy, and excision of the abdominoscrotal hydrocele. We discuss the diagnosis and treatment of this combination, which has not been previously reported.

Effect of testicular biopsy in childhood on spermatogenesis, fertility, and paternity in adulthood--a mouse model study

OBJECTIVES

To study the effect of testicular biopsy in childhood on spermatogenesis, fertility, and paternity in subsequent adulthood using an animal model. Considerable controversy exists as to whether testicular biopsy should be performed in children.

METHODS

Four-week-old male ICR mice were subjected to unilateral testicular biopsy (group 1), bilateral biopsy (group 2), or a sham operation (group 3). At 8 weeks of age, the testicular weight, seminiferous tubular diameter, and manifestation of apoptosis were examined. The motility of sperm obtained from the epididymides of the same testes was also examined. Fertility and paternity was assessed in each mouse by housing it with 2 age-matched females for 2 weeks.

RESULTS

No significant differences were found in the testicular weight, mean seminiferous tubular diameter, or number of apoptotic germ cells between the biopsied and unbiopsied side in group 1 or between groups 2 and 3. No significant differences were noted in the average sperm motility rate between the biopsied (30.5% +/- 14.5%) and unbiopsied side (35.8% +/- 19.2%) in group 1, or between groups 2 (37.6% +/- 18.0%) and 3 (39.3% +/- 10.0%). All females who coupled with the male mice in all groups became pregnant. The average number of offspring from the 2 female mice was not significantly different among the three groups (group 1, 13.1 +/- 2.3; group 2, 12.3 +/- 2.0; and group 3, 11.3 +/- 3.0).

CONCLUSIONS

The spermatogenesis, fertility, and paternity of mature mice were unaffected by testicular biopsy in childhood.

Role of endocytosis in cellular uptake of sex steroids

Androgens and estrogens are transported bound to the sex hormone binding globulin (SHBG). SHBG is believed to keep sex steroids inactive and to control the amount of free hormones that enter cells by passive diffusion. Contrary to the free hormone hypothesis, we demonstrate that megalin, an endocytic receptor in reproductive tissues, acts as a pathway for cellular uptake of biologically active androgens and estrogens bound to SHBG. In line with this function, lack of receptor expression in megalin knockout mice results in impaired descent of the testes into the scrotum in males and blockade of vagina opening in females. Both processes are critically dependent on sex-steroid signaling, and similar defects are seen in animals treated with androgen- or estrogen-receptor antagonists. Thus, our findings uncover the existence of endocytic pathways for protein bound androgens and estrogens and their crucial role in development of the reproductive organs.