Age-Related and Individual Anatomical Variation in Testicular Topography in Human Fetuses

At present, male infertility remains an urgent medical concern. From year to year, despite advances in methods of diagnosis and treatment, medicine encounters an increasing number of infertile couples with male infertility playing a leading role. Prerequisites for fertility disorders very frequently appear in childhood. Urologists consider cryptorchidism a leading cause of male infertility. The aim of our study was to establish the relationship between testicular descent to the scrotum and the age of the fetus. Material and methods. The study was conducted using 195 specimens of male fetuses aged 4–10 months with 81.0–375.0 mm parietalcoccygeal length (PCL) using the methods of macromicroscopic, conventional, and microslide preparation under control of binocular loupes and morphometry. Results. At the beginning of the fetal period of human ontogenesis (fetuses 81.0–135.0 mm PCL), the right and left testicles are mainly located above the corresponding deep inguinal ring and they are less often located in a region of the iliac fossae. An analysis of topographic and anatomical features of the male reproductive glands in 5-month-old fetuses (136.0–185.0 mm PCL) revealed that the testicles were located within the large pelvis, with the lower end of both the right and left testicles located above the entrance to the deep inguinal ring at a distance that equals the length of the pelvic part of the gubernaculum testis—3.2 ± 0.3 mm (right) and 2.8 ± 0.2 mm (left). In 11 fetuses aged 7 months (231.0–270.0 mm PCL), the lower ends of the testicles and their gubernaculum testis are immersed in the corresponding deep inguinal ring. In eight fetuses, the testicles were within the deep inguinal ring. A combination of many factors contributes to the final migration of a testicle through the inguinal canal into the scrotum (fetuses: 270.0 cm–290.0 mm PCL), including muscle contraction of the anterolateral abdominal wall, an increase in intra-abdominal pressure, contractile capacity of the gubernaculum testis of the testicle, the vaginal process of the peritoneum, and the neuro-muscular system. We believe that the gubernaculum testis is a particularly significant factor in testicular descent to the scrotum. The gubernaculum testis is maximally developed prior to migration of a testicle through the inguinal canal (eighth month of antenatal development), as evidenced by the prevalence of smooth muscle cells over connective tissue elements. An analysis of testicular topography in fetuses aged 9 months (311.0–345.0 mm PCL) revealed that testicles were located in the scrotum in nine fetuses, near the superficial inguinal ring in six fetuses, within the inguinal canal in four cases, and in the deep inguinal ring in one case. In fetuses aged 10 months (346.0–375.0 mm PCL), testicles were located in the scrotum in 13 cases and within the inguinal canal in seven cases. According to our research, the fusion of layers of the vaginal process of the peritoneum occurs in fetuses aged 9–10 months, resulting in the disappearance of the communication of its cavity with the peritoneum. A delay in the fusion of the peritoneal vaginal process layers at the end of the fetal period is an anatomic prerequisite for the occurrence of congenital inguinal-scrotal hernias. Conclusions. It has been found that the rate of testicular descent to the scrotum does not always coincide with the corresponding stage of fetal development. An accelerated development of the gubernaculum testis in fetuses aged 5–8 months is a major factor of heterochronic development of a testicle and subsequent testicular descent into the scrotum.     

Testicular organogenesis in the fetal calf: interstitial endocrine (Leydig) cell development

The development of the interstitial endocrine (Leydig) cells of the fetal testis in the calf is described and correlated with a swelling reaction of the gubernaculum and normal, prenatal descent of the testis. An hydroxysteroid dehydrogenase (HSD) procedure is used to determine the onset of functional activity for the interstitial endocrine cells (IEC). The NADH control procedure was strongly positive for the IECs at all ages investigated, indicating that these cells utilize the pyridine nucleotide as a coenzyme for oxireduction conversions. The 3 alpha- and 3 beta-HSD reactions were strongly positive and lightly positive, respectively, demonstrating that these cells contain the HSDs commonly utilized in the early steroidogenesis. TEM revealed structural evidence of this differentiating steroidogenic capability within IECs. During the period of the swelling reaction there is a functional IEC population, but there is no evidence presented by this study for a causal relationship of the gubernacular swelling reaction and subsequent normal descent of the testis into the scrotum.     

La descente testiculaire

Gonadal development is intimately linked to that of the mesonephros. The primordial testes differentiate in the dorsal region of the embryonic abdomen, behind the coelomic cavity. To reach their final location within the scrotum, the testes descend into the pelvis, pass through the abdominal wall by the inguinal canal, and attach to the base of the scrotal pouch. Testicular migration therefore comprises three stages, each requiring its own mecanism (s). The genital ducts (epididymis, vas deferens) and ligament which attaches the testis to the scrotal wall (gubernaculum testis) certainly play an essential role in these migratory events. The first phase is quite passive, associated with the growth of the abdominal cavity. In the second phase, the gubernaculum enlarges and shortens, pulling the testis through the inguinal canal. Finally, the gubernaculum, as a short, fibrous ligament, attaches the testis to the scrotal wall.     

Hormonal treatment for unilateral inguinal testis: comparison of four different treatments.

BACKGROUND: Hormonal treatment of cryptorchidism has been used since the 30s, but controversies persist on its efficacy. It is also unclear whether there are differences with the use of different hormonal trials. Aims: To evaluate the efficacy of four hormonal treatments on testicular descent in a homogeneous group of cryptorchid boys. PATIENTS: 155 patients (age 10-48 months) with unilateral inguinal palpable testis were studied. Methods: The patients were subdivided into four groups according to hormonal treatment: group 1 = hCG [500 IU/week (if the chronological age was <2 years) or 1,000 IU/week (if the chronological age was >2 years) for 6 weeks]; group 2 = hCG + hMG (hCG as in group 1 + hMG 75 IU/week for 6 weeks); group 3 = GnRH (1,200 microg/daily for 28 days); group 4 = GnRH + hCG (1,200 microg/daily for 28 days + 1,500 IU/week for 3 weeks, respectively). The results were evaluated at the end of the treatment period and 6 months later to exclude temporarily positive results. RESULTS: At the end of the hormonal therapy, scrotal testicular descent was present in 30 of 155 boys (success rate 19.3%). Seven testes relapsed during follow-up (23.3%). The long-term success rate was 14.8% (23/155 testes). No significant differences were observed in success rates as well as in relapse rates among the four groups. CONCLUSIONS: Hormonal therapy induced permanent testicular descent in a minority of young cryptorchid boys with inguinal palpable testis. Similar results were obtained with four different trials.     

The overexpression of the insl3 in female mice causes descent of the ovaries

Testicular descent in mice is dependent upon proper outgrowth of the gubernaculum primordia under the influence of the insulin-like 3 gene product (Insl3). Deletion of this gene prevents gubernaculum growth and causes bilateral cryptorchidism. In vitro experiments have led to the suggestion that Insl3 and androgens together induce outgrowth of the gubernacular primordia. The experiments reported here were designed specifically to determine whether in vivo the Insl3-mediated gubernaculum development is independent of androgens. To that effect transgenic male and female mice were generated that overexpressed Insl3 in the pancreas during fetal and postnatal life. Expression of the transgenic allele in the Insl3-deficient mice rescued the cryptorchidism in male mutant, indicating that the islet beta-cells efficiently processed the Insl3 gene product to the functional hormone. All transgenic females displayed bilateral inguinal hernia. The processus vaginalis developed containing intestinal loops. The Müllerian derivatives gave rise to oviduct, uterus, and upper vagina, and Wolffian duct derivatives were missing, indicating the absence of the androgen- and anti-Müllerian hormone-mediated activities in transgenic females. The ovaries descended into a position over the bladder and attached to the abdominal wall via the well developed cranial suspensory ligament and the gubernaculum. Administration of dihydrotestosterone during prenatal development suppressed formation of the cranial suspensory ligament and thereby allowed the descent of the ovaries into the processus vaginalis. These results suggest that Insl3-mediated activity induces gubernaculum development and precludes a role of androgen in this process. Furthermore, the transgenic females exhibit reduced fertility, which is due to fetal mortality during midgestation.     

Effect of temperature and the role of testicular descent on post-natal testicular androgen production in the mouse.

Testes from mice aged 3, 15, 25, 30 or 60 days were incubated under basal conditions or in the presence of hCG. One testis from each animal was incubated at 37 degrees C while the contralateral testis was incubated at 32 or 34 degrees C. During development total androgen production in response to hCG (at 32 degrees C) showed a marked increase between 15 and 30 days. The major androgens secreted at this time were testosterone and 5 alpha-androstane-3 alpha,17 beta-diol. There was little change in total androgen production between 30 and 60 days but by 60 days testosterone was the dominant androgen. Both basal and hCG-stimulated androgen production were temperature sensitive. These effects were most pronounced at 30 and 60 days with androgen production significantly inhibited at 37 degrees C. To examine the role of testicular descent in regulating steroidogenesis animals were rendered unilaterally cryptorchid at 19 days of age. At 25 days, when descent is normally completed in the mouse, there was no significant difference in steroidogenesis between scrotal and abdominal testes. By 30 days, however, the steroidogenic potential of the abdominal testis was significantly lower than that of the scrotal testis. These results show that testicular steroidogenesis is sensitive to temperature changes around the time of testicular descent, although descent itself is not required to achieve an adult level of steroidogenesis. The results also show, however, that testicular descent is required to maintain the adult level of steroidogenesis.     

Müllerian inhibiting substance production and testicular migration and descent in the pouch young of a marsupial

The ontogeny of Müllerian inhibiting substance (MIS) production by the developing testis of an Australian marsupial, the tammar wallaby (Macropus eugenii), was determined during pouch life using an organ-culture bioassay of mouse fetal urogenital ridge. This information was related to the morphological events during testicular migration and descent. MIS biological activity was found in testes (but not ovaries or liver) of pouch young from 2 to 85 days of age. MIS production had commenced by day 2, which is within a day of the first gross morphological signs of testicular differentiation. Müllerian duct regression occurred between 10 and 30 days, which partly coincided with testicular migration to the inguinal region and enlargement of the gubernacular bulb (15 to 30 days). These observations are consistent with the hypothesis that MIS may be involved in testicular transabdominal migration. The epididymis commenced development and growth only after the testis had descended through the inguinal ring. This provides no support for the suggestion that the epididymis is involved in testicular descent into the scrotum. The basic sequence of events in post-testicular sexual differentiation in the wallaby is sufficiently similar to that seen in eutherian mammals to make it an excellent experimental model for future studies of testicular differentiation, migration and descent.     

Targeted disruption of the Insl3 gene causes bilateral cryptorchidism.

The sexual dimorphic position of the gonads in mammals is dependent on differential development of two ligaments, the cranial suspensory ligament (CSL) and the gubernaculum. During male embryogenesis, outgrowth of the gubernaculum and regression of the CSL result in transabdominal descent of the testes, whereas in the female, development of the CSL in conjunction with failure of the gubernaculum development holds the ovaries in a position lateral to the kidneys. Several lines of evidence suggest that regression of the CSL and induction of gubernaculum development are mediated by testosterone and a yet unidentified testicular factor, respectively. The Insl3 gene (originally designated Ley I-L), a member of the insulin-like superfamily, is specifically expressed in Leydig cells of the fetal and postnatal testis and in theca cells of the postnatal ovary. Here we show that male mice homozygous for a targeted deletion of the Insl3 locus exhibit bilateral cryptorchidism with free moving testes and genital ducts. These malformations are due to failure of gubernaculum development during embryogenesis. In double-mutant male mice for Insl3 and androgen receptor genes, testes are positioned adjacent to the kidneys and steadied in the abdomen by the CSL. These findings demonstrate, that the Insl3 induces gubernaculum development in an androgen-independent way, while androgen-mediated regression of the CSL occurs independently from Insl3.     

13 Years' experience with the combined hormonal therapy of cryptorchidism.

PURPOSE: We analyze the results of the combined treatment with luteinizing hormone releasing hormone (LH-RH) and human chorionic gonadotropin (HCG) of a large series of patients with cryptorchidism. MATERIALS AND METHODS: Between 1987 and 1999 and after strict differentiation between cryptorchid, retractile and gliding testes, 2,467 boys with 2,962 cryptorchid-gliding testes were treated with the combined hormonal therapy. LH-RH was administrated as a nasal spray at a dosage of 1.2 microg daily for a period of 4 weeks. HCG was injected intramuscularly, 5 times at 2-day intervals at a dosage adjusted according to the age. RESULTS: In the prospective study 2,476 boys with 2,962 cryptorchid testes were hormonally treated. Of the 2,962 evaluated cases 1,200 (40.52%) have been treated surgically after the hormone therapy. In 1,762 cases, 59.48% of cryptorchid testes were in the scrotum after combined hormone treatment. CONCLUSIONS: Treatment with LH-RH and HCG induced the descent of the testes to a normal scrotal position of boys with cryptorchidism in 59.48% of the evaluated cases. The combined treatment was effective for inducing descent of cryptorchid and gliding testes. According to the evaluated intraoperative findings, the failure of the combined therapy in 40.52% of the cases is due to the fact that the free descent is limited by local factors such as anatomical alterations of the inguinal canal, epididymal abnormalities or ectopic distal attachment of the lig. testis.     

Cytology of mesothelioma of the tunica vaginalis metastatic to the lung

The case of a 63-year-old man with malignant mesothelioma of the tunica vaginalis testis confirmed by electron microscopy is presented. The tumor recurred in the scrotal skin and subsequently metastasized to the inguinal and retroperitoneal lymph nodes. Four and a half years after the original diagnosis, pulmonary metastases were discovered by cytologic examination of bronchial washings and confirmed by transbronchial lung biopsy. The cytologic features of the metastatic malignant mesothelial cells are described and compared to those of mesothelioma cells in body cavity fluids. The role of cytology in the early detection of such tumors is discussed.     

Treatment of an undescended testis with human chorionic gonadotropin (HCG)

Seventy one patients with ectopic testis of age between 2 and 11.5 years were treated with human chorionic gonadotropin (HCG) at doses recommended by the International Health Foundation. The descent of testis to the scrotum was achieved in almost half of the treated boys (49.3%). The descent was successful mainly in cases of lower inguinal position of the undescended testicle, and only rarely when the testicle was situated higher. The descent was never successful in cases when the scrotum was small and underdeveloped.     

Abnormalities of testicular descent

Testicular descent occurs in two stages. The transabdominal phase (8–15 weeks) is controlled by enlargement of the caudal genito-inguinal ligament (gubernaculum) and regression of the cranial ligament. Insulin-like 3 from the Leydig cell appears to be the prime stimulator of gubernacular growth, augmented by Müllerian inhibiting substance/anti-Müllerian hormone. Testosterone causes regression of the cranial ligament. The inguinoscrotal phase (25–35 weeks) requires the migration of the gubernaculum from the groin to the scrotum; this migration is guided by the genito-femoral nerve releasing calcitonin gene-related peptide under the influence of androgen. The neonatal gonocyte transforms into a type A spermatogonium at 3–12 months of age, a step that is now known to be crucial for subsequent fertility, as the stem cells for spermatogenesis are created in this structure. This step is blocked in undescended testis and, hence, orchidopexy is currently recommended at 6–12 months of age. Congenital cryptorchidism is caused by the failure of gubernacular migration to the scrotum (1%–2%) but we now recognise that another 1%–2% of boys have acquired cryptorchidism, secondary to the failure of spermatic cord elongation with growth of the boy. These latter cases come to operation at 5–10 years of age. Surgery remains the mainstay of treatment, as hormonal therapy has not been proven to be effective, presumably because testicular descent is a complex anatomical mechanism.     

Altered concentrations of gonadotrophin, prolactin and GnRH receptors, and endogenous steroids in the abdominal testes of adult unilaterally cryptorchid rats

Testicular descent was prevented unilaterally in newborn rats by cutting the gubernaculum testis. At 100 days of age, the number of Leydig and Sertoli cells per testis, the concentration of receptors for LH, FSH, prolactin and GnRH, and endogenous concentrations of progesterone and testosterone were determined. The weight of the abdominal testes was reduced by 80%, but in spite of this they contained as many Sertoli (32.8 +/- 1.3 X 10(6), mean +/- s.e.m., n = 6) and Leydig (28.2 +/- 1.7 X 10(6) cells as did scrotal testes (32.1 +/- 2.5 X 10(6) and 24.3 +/- 1.2 X 10(6) respectively). The numbers of receptors for LH (3.2 +/- 0.2 and 1.0 +/- 0.2 pmol/testis, mean +/- s.e.m., n = 11), FSH (358 +/- 11.0 and 96.3 +/- 12.6 fmol/testis) and prolactin (535 +/- 32.7 and 92.4 +/- 13.2 fmol/testis) were reduced (P less than 0.001) in abdominal testes, but the number of GnRH receptors was unaffected (8.9 +/- 1.4 and 12.1 +/- 1.8 fmol/testis, n = 6). Testicular testosterone concentration (30.9 +/- 4.4 vs 15.4 +/- 3.2 ng/g, n = 11, P less than 0.001), but not that of progesterone (0.87 +/- 0.10 vs 1.01 +/- 0.21 ng/g), was decreased in abdominal testes. The decreased receptor and androgen values reflect functional disturbances in the abdominal testes. The changed local milieu within abdominal testes may reduce hormone receptor concentrations which are then involved in the observed Leydig cell dysfunction.     

La Vaso-Vasostomie Pelvi-Scrotale pour obstruction inguinale du canal déférent: Revue de la littérature

Pelvi- scrotal vasovasostomy for inguinal obstruction of the vas deferens: Review of the literature The recent development of assisted reproductive technologies has greatly modified evaluation and treatment of infertility and reconstructive surgery has been challenged over recent years by IVF techniques in the case of obstructive azoospermia. Inguinal hernia repair is a frequent surgical procedure that may cause vas deferens obstruction. Polypropelene mesh induces an inflammatory reaction followed by a dense fibroblastic reaction surrounding the spermatic cord. Azoospermia secondary to mesh hernia repair is one of the most difficult cases for andrological reconstructive surgery. Up until now, open vasovasostomy has been the only available technique, but gives poor results. A new option called laparoscopic pelvi- scrotal vaso- vasostomy PSW consists of mobilization of the endopelvic vas deferens from the deep inguinal ring to the superficial ring, allowing tension- free anastomosis with the distal part of the vas. The authors conclude that this technique is reliable, efficient and reproducible. It can be performed on both sides during the same procedure and it may open new possibilities for these patients to recover fertility and to father children naturally.     

Diethylstilbestrol regulates mouse gubernaculum testis cell proliferation via PLC‐Ca2+‐CREB pathway

Recent evidence suggested a positive correlation between environmental estrogens (EEs) and high incidence of abnormalities in male urogenital system, but the mechanism remains unclear. Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen that disrupts the morphology and proliferation of gubernaculum testis cells, but the underlying mechanism is unclear. In this study, mouse gubernaculum testis cells were pretreated with phospholipase C (PLC) inhibitor U‐73122 and then treated with DES. The results demonstrated that U‐73122 impaired DES‐evoked intracellular Ca2+ mobilization in gubernaculum testis cells and inhibited DES‐induced proliferation of gubernaculum testis cells. Mechanistically, we found that U‐73122 inhibited DES‐induced activation of cAMP‐response element binding protein (CREB) in gubernaculum testis cells. In conclusion, these data suggest that the effects of DES on mouse gubernaculum testis cells are mediated by PLC‐Ca²⁺‐CREB pathway.

Significance of the study

Environmental estrogens remain a serious threat to male reproductive health, and it is important to understand the mechanism by which EEs affect the male productive system. Here we explore potential mechanisms how the proliferation and contractility of gubernaculum testis cells are regulated by diethylstilbestrol. Our findings provide the first evidence that PLC‐Ca²⁺‐CREB signalling pathway mediates the nongenomic effects of diethylstilbestrol on gubernaculum testis cells. These findings provide new insight into the role of diethylstilbestrol in the aetiology of male reproductive dysfunction and will help develop better approaches for the prevention and therapy of male reproductive malformation.