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.

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.

New insights into the morphogenesis of the gubernaculum testis and the inguinal canal.

There is no consensus about the role of the gubernaculum testis (GT). Nineteen human embryos (Carnegie stages 15-23), 36 fetuses (9 weeks to term), and eight neonates were examined. All the embryos and 25 fetuses (from weeks 9-16) were processed for paraffin wax histology and serially sectioned at 10 µm thickness. The remaining 11 fetuses and the eight neonates were fresh specimens that were dissected under a surgical microscope. The GT appeared during the embryonic period (stages 17-23) with a horseshoe-shaped mesenchyme condensation of the superior concavity, which was observed in four different topographical regions sequentially through development. The GT was not attached at either of its ends in any of the specimens, not to the gonad or in the scrotal sac. The inguinal canal differentiates around the inguinal portion of the GT during the late embryonic period. After stage 21, the GT appears enveloped by an evagination of the peritoneal cavity. It has few striate muscular fibers and vessels. Although the GT does not appear to have the role traditionally attributed to it, it is still an essential structure and indirectly facilitates the descent of the testes. It contributes to the formation of the inguinal canal and then forges the pathway that the testes will subsequently take through the inguinal canal as they migrate from the abdominal cavity into the scrotal sac. Clin. Anat. 30:599-607, 2017. © 2017 Wiley Periodicals, Inc.

Fetal Rat Gubernaculum Mesenchymal Cells Adopt Myogenic and Myofibroblast-Like Phenotypes.

PURPOSE: Gubernaculum-cremaster complex development is hormonally regulated and abnormal in a cryptorchid rat model. Using cell tracking techniques and imaging we studied myogenic phenotypes and fates in the fetal rat gubernaculum-cremaster complex. MATERIALS AND METHODS: Embryonic day 17 gubernaculum-cremaster complexes were labeled with CellTracker™ or the DNA synthesis marker EdU (5-ethynyl-2'-deoxyuridine), or immobilized in Matrigel® and grown in culture. Embryonic day 17 to 21 gubernaculum-cremaster complex sections and cells were imaged using wide field and deconvolution immunofluorescence microscopy, and muscle and/or myofibroblast specific antibodies. Deconvolved image stacks were used to create a 3-dimensional model of embryonic day 21 gubernaculum-cremaster complex muscle. RESULTS: PAX7 (paired box 7) positive and myogenin positive muscle precursors were visible in a desmin-rich myogenic zone between muscle layers that elongated and became thicker during development. Gubernaculum-cremaster complex inner mesenchymal cells expressed desmin and αSMA (α smooth muscle actin) at lower levels than in the myogenic zone. After pulse labeling with CellTracker or EdU mesenchymal cells became incorporated into differentiated muscle. Conversely, mesenchymal cells migrated beyond Matrigel immobilized gubernaculum-cremaster complexes, expressed PAX7 and fused to form striated myotubes. Mesenchymal gubernaculum-cremaster complex cell lines proliferated more than 40 passages and showed contractile behavior but did not form striated muscle. Our 3-dimensional gubernaculum-cremaster complex model had 2 orthogonal ventral layers and an arcing inner layer of muscle. CONCLUSIONS: Our data suggest that mesenchymal cells in the peripheral myogenic zone of the fetal gubernaculum-cremaster complex contribute to formation of a distinctively patterned cremaster muscle. Nonmyogenic, desmin and αSMA positive gubernaculum-cremaster complex mesenchymal cells proliferate and have a myofibroblast-like phenotype in culture. Intrinsic mechanical properties of these divergent cell types may facilitate perinatal inversion of the gubernaculum-cremaster complex.

Anatomical Study on the Descent of Testis in Prenatal Goat (Capra hircus) / Estudio Anatómico del Descenso Testicular Prenatal en la Cabra (Capra hircus)

A study was conducted on 70 embryo/ foetii of goats to observe the descent of testis. These foetii were grouped into I (0-30 days), II (31-60 days), III (61-90 days), IV (91-120days) and V (121 days up to term, having 14 embryos/ foetii in each group. The genital ridge was observed at 1.2cm CRL (23 day) on the ventromedial aspect of mesonephros. At 42nd day, the genital ridge developed into cylindrical structure, the testis, located in the middle of metanephros. The abdominal migration was completed upto 88th day. The testes were situated in the inguinal canal from 89th to 95th day. From 90th day onward, scrotal migration had been observed, however the testis did not reach the base of the scrotum up to term. During the descent of testis, a peritoneal fold detached from the caudal end of the gonad and extended up-to the abdominal floor on 42nd day, known as gubernaculum. In the initial stages of pregnancy it was thin, whitish, jelly like. On 70th day it was enveloped by processus vaginalis. In group V, it became hardened, longer and cord like.

Para observar el descenso de los testículos se realizó un estudio en 70 embriones/fetos de cabra. Estos fetos se agruparon en 5 grupos: I (0-30 días), II (31-60 días), III (61-90 días), IV (91 120 días) y V (121 días hasta término, con 14 embriones / fetos en cada grupo. La cresta genital se observó a 1,2cm CRL (23 días) en la cara ventromedial del mesonefros. En el día 42 día, la cresta genital se convirtió en estructura cilíndrica y los testículos se encontraban en el centro del metanefros. La migración abdominal se completó en 88 días. Los testículos están situados en el canal inguinal entre los 89 y 95 días. Del día 90 en adelante, se observó la migración escrotal, sin embargo, el testículo no llegó a la base del escroto hasta el término del desarrollo. Durante el descenso de los testículos, a los 42 días, un pliegue peritoneal (gubernaculum testis) separado del extremo caudal de la gónada, se extendió hacia el suelo-abdominal. En las etapas iniciales de la preñez la gónada era delgada, blanquecina, gelatinosa. En el día 70 el testículo fue envuelto por el proceso vaginal. En el grupo V, el testículo se había endurecido y alargado asemejándose a una cuerda.