Seminiferous tubule degeneration in human cryptorchid testes

Evaluation of testicular stiffness in boys with unilateral cryptorchidism after orchiopexy by ultrasound strain elastography

PURPOSE

We assessed the stiffness of unilateral undescended testes after orchiopexy, examining its value in tracking histopathological changes and fertility potential during postoperative follow-up. Additionally, we explored the optimal timing for surgery based on testicular stiffness.

PATIENTS AND METHODS

Thirty-six boys who had been diagnosed with unilateral undescended testis and treated with orchiopexy were included in the study. Testicular stiffness was evaluated several times over respective follow-up periods by ultrasound strain elastography after orchiopexy. The strain ratios were measured as the ratios of the elasticities of the descended testis to those of the operated testes. The patients were divided into two groups based on the age at which they underwent orchiopexy:under < 2 years (Group A) and ≥ 2 years (Group B).

RESULTS

The mean strain ratios were 0.90 ± 0.32 and 0.92 ± 0.20 in Groups A and B, respectively. In Group A, the strain ratio was constant regardless of postoperative months (r = 0.01, p = 0.99); however, in Group B, it tended to increase with postoperative months (r = 0.42, p = 0.07).

CONCLUSIONS

Evaluation of testicular stiffness may be useful for the estimation of histopathological changes and fertility potential in boys with unilateral undescended testes at follow-up appointments after orchiopexy. Our data indicate that performing orchiopexy as early as possible may be recommended to avoid testicular damage.

Cryptorchidism: The dog as a study model

Cryptorchidism (CO) or undescended testicle is an abnormality of male gonadal development that can generate long-term repercussions in men, such as infertility and germ cell neoplasia in situ (GCNIS). The origin of these alterations in humans is not completely clear, due to the absence of an animal model with similar testicular development as in humans with CO. This work intends to describe the testicular histological development of dogs with congenital CO, and determine whether the species could adequately serve as a study model for this pathology in humans. The study was carried out with 36 dogs, equally distributed in two groups: healthy control (CTRL) and CO groups. The contralateral testis to the undescended one in CO group of the animals was considered and analyzed. Each group was subdivided in three stages of development: (1) peripubertal stage (6–8 months), (2) young adult (9–48 months) and (3) senile (49–130 months). Histological development, the presence of cells with gonocyte morphology, cell proliferation, testicular lipoperoxidation and hormonal concentrations of testosterone, estradiol, FSH and LH were evaluated and described. In the cryptorchid testes, the first histological alterations appeared from the first stage of development and were maintained until the senile stage. A pronounced testicular lipoperoxidation occurred only in the second stage of development. The histological alterations due to CO were markedly evident in the young adult stage. Testosterone concentrations witnessed a decrease starting from in the second stage and kept on until the last stage. The contralateral testes of the CO animals showed alterations that positioned them between the control and CO testes. Testicular development of dogs with CO is similar to that of humans. The results of the study suggest that this species could serve as a suitable model for the study of CO in humans.

Evaluation of Pediatric Undescended Testes with Elastosonography

Background

Undescended testes, which are defined as the failure of testes to descend to scrotum, are the most common developmental defect in male infants. Indirect evaluation of histologic damage can be performed with the help of palpation during operation. Hard texture of testes tissue is likely related with histological damage. Real-time elastography is an emerging technology of ultrasonic imaging of soft tissue strain and elasticity, it aims at providing information regarding the mechanical properties of tissues, such as their hardness or stiffness. This study aim was to investigate the changes in strain and elasticity of testes tissue by using elastography technique.

Materials and methods

A total of 32 patients, who had undescended testes were included in this study. Only two patients had bilateral undescended testes, other patients had unilateral. The age of the patients were recorded according to the time of ultrasonographic (USG) examination. The undescended testes was displayed in the elastographic box with the neighbouring subcutaneous fat tissues. The strain ratios were measured as the ratios of the elasticities of the subcutaneous fat tissue to the elasticities of the undescended testes.

Results

A total of 32 patients with 34 testes were included in the study. The mean age of the patients with undescended testes was 32.6 months (range 7-60 months). The mean strain ratios were 0.67 (range 0.12-1.41) for the undescended testes and there were no significant differences in undescended testes strain ratios related to patient age (p = 0.453).

Conclusion

This preliminary study showed that there were no significant fibrosis which can be demonstrated with elastosonography before the age of 5 years old. Additional studies with his-topathological results are needed to identify sensitivity and specificity of elastosonography in undescended testis and in planning optimal operation time for these patients.

Establishment of a surgically induced cryptorchidism canine recipient model for spermatogonial stem cell transplantation

Transplantation of spermatogonial stem cells (SSCs) in experimental animal models has been used to study germ line stem cell biology and to produce transgenic animals. The species-specific recipient model preparation is important for the characterization of SSCs and the production of offspring. Here, we investigated the effects of surgically induced cryptorchidism in dog as a new recipient model for spermatogonial stem cell transplantation. Artificially unilateral or bilateral cryptorchidism was induced in ten mature male dogs by surgically returning the testis and epididymis to the abdominal cavity. The testes and epididymides were collected every week after the induction of artificial cryptorchidism (surgery) for one month. To determine the effect of surgical cryptorchidism, the seminiferous tubule diameter was measured and immunohistochemistry using PGP9.5 and GATA4 antibodies was analyzed. The diameters of the seminiferous tubules of abdominal testes were significantly reduced compared to those of the scrotal testes. Immunohistochemistry results showed that PGP9.5 positive undifferentiated spermatogonia were significantly reduced after surgical cryptorchidism induction, but there were no significant changes in GATA-4 positive sertoli cells. To evaluate the testis function recovery rate, orchiopexy was performed on two dogs after 30 days of bilateral cryptorchidism. In the orchiopexy group, SCP3 positive spermatocytes were detected, and spermatogenesis was recovered 8 weeks after orchiopexy. In this study, we provided optimum experimental conditions and time for surgical preparation of a recipient canine model for SSC transplantation. Additionally, our data will contribute to recipient preparation by using surgically induced cryptorchidism in non-rodent species.

Extracellular matrix: recent advances on its role in junction dynamics in the seminiferous epithelium during spermatogenesis

Spermatogenesis takes place in the seminiferous epithelium of the mammalian testis in which one type A1 spermatogonium (diploid, 2n) gives rise to 256 spermatids (haploid, 1n). To accomplish this, developing germ cells, such as preleptotene and leptotene spermatocytes, residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier (BTB) entering into the adluminal compartment for further development into round, elongating, and elongate spermatids. Recent studies have shown that the basement membrane in the testis (a modified form of extracellular matrix, ECM) is important to the event of germ cell movement across the BTB because proteins in the ECM were shown to regulate BTB dynamics via the interactions between collagens, proteases, and protease inhibitors, possibly under the regulation of cytokines. While these findings are intriguing, they are not entirely unexpected. For one, the basement membrane in the testis is intimately associated with the BTB, which represents the basolateral region of Sertoli cells. Also, Sertoli cell tight junctions (TJs) that constitute the BTB are present side-by-side with cell-cell actin-based adherens junctions (AJ, such as basal ectoplasmic specialization [ES]) and intermediate filament-based desmosome-like junctions. As such, the relative morphological layout between TJs, AJs, and desmosome-like junctions in the seminiferous epithelium is in sharp contrast to other epithelia where TJs are located at the apical portion of an epithelium or endothelium, furthest away from ECM, to be followed by AJs and desmosomes, which in turn constitute the junctional complex. For another, anchoring junctions between a cell epithelium and ECM found in multiple tissues, also known as focal contacts (or focal adhesion complex, FAC, an actin-based cell-matrix anchoring junction type), are the most efficient junction type that permits rapid junction restructuring to accommodate cell movement. It is therefore physiologically plausible, and perhaps essential, that the testis is using some components of the focal contacts to regulate rapid restructuring of AJs between Sertoli and germ cells when germ cells traverse the seminiferous epithelium. Indeed, recent findings have shown that the apical ES, a testis-specific AJ type in the seminiferous epithelium, is equipped with proteins of FAC to regulate its restructuring. In this review, we provide a timely update on this exciting yet rapidly developing field regarding how the homeostasis of basement membrane in the tunica propria regulates BTB dynamics and spermatogenesis in the testis, as well as a critical review on the molecular architecture and the regulation of ES in the seminiferous epithelium.

Sertoli cell tight junction dynamics: their regulation during spermatogenesis

During spermatogenesis, developing preleptotene and leptotene spermatocytes must translocate from the basal to the adluminal compartment of the seminiferous epithelium so that fully developed spermatids (spermatozoa) can be released to the tubular lumen at spermiation. It is conceivable that the opening and closing of the inter-Sertoli tight junctions (TJs) that constitute the blood-testis barrier are regulated by an array of intriguingly coordinated signaling pathways and molecules. Several molecules have been shown to regulate Sertoli cell TJ dynamics; they include, for example, transforming growth factor beta3 (TGFbeta3), occludin, protein kinase A, protein kinase C, and signaling pathways such as the TGFbeta3/p38 mitogen-activated protein kinase pathway. Yet the mechanisms that regulate these events are essentially not known. This minireview summarizes some of the recent advances in the study of TJ dynamics in the testis and reviews several models that can be used to study TJ dynamics. It also highlights specific areas for future research toward understanding the precise physiological relationship between junction dynamics and spermatogenesis.

Testosterone secretion and semen plasma enzyme activity in rams with genital pathology stimulated with GnRH

Testosterone secretion in response to GnRH stimulation and enzymatic activity of semen plasma was evaluated comparatively in rams with or without genital abnormality. Scrota, testes and epididymides of 128 rams between 1.5 and 6 years old from various breeds were examined clinically and ultrasonographically. Bilaterally cryptorchid rams (n = 2), and rams with focal testicular degeneration (n = 3) or unilateral sperm granuloma localized in the caput (n = 3) epididymis or the cauda epididymis (n = 3), diagnosed by either clinical or ultrasonographic examination, were selected for the further investigation of spermatologic parameters, testosterone secretion in response to GnRH stimulation, and enzymatic activity of semen plasma before histopathologic confirmation of lesions. Except for the cryptorchid rams, sperm parameters determined in ejaculates were similar to intact controls (n = 3). GnRH administration increased plasma testosterone levels significantly irrespective of the type of genital pathology (P < 0.01). The testosterone response calculated based on area under the curve following GnRH administration in rams having genital abnormality was not significantly different from the controls. Aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activity in the semen plasma varied between rams, with the lowest mean values in the bilaterally cryptorchid group (P < 0.05). Spermatic granuloma localized either in the caput or cauda of the epididymis was associated with a significant reduction in the semen plasma AST activity compared to controls (P < 0.01). In conclusion, our results indicated that the ability of testicular tissue to secrete testosterone in response to GnRH stimulation in rams with bilateral cryptorchidism, focal testicular degeneration and unilateral sperm granuloma was similar to that of intact controls, and that reduced semen plasma AST activity may have a diagnostic value in the diagnosis of the epididymal obstruction in rams. Focal testicular degeneration did not influence AST, alkaline phosphatase (ALP) and LDH activity in semen plasma.

Pattern of Sertoli cell degeneration in cryptorchid prepubertal testes

Seventy-three testicular biopsies from 54 children (aged 2 months-14 years) with undescended testes were examined by light and electron microscopy. The biopsies included abdominal, inguinally fixed, inguinally moveable, and retractile testes. Alterations in Sertoli cell morphology were found in all biopsies. The alterations included dilated elements of rough endoplasmic reticulum, vacuolization of the cytoplasm, mitochondria with poorly preserved cristae, increase in electron density of the matrix, elongation of the nuclei, and irregularities of the nuclear membrane. According to the numerical appearance of these cells and to the extent of lesions in single Sertoli cells, seven phases in the continuous process of tubular alteration were distinguished. The most severe tubular damaged (phase VII) occurred when the seminiferous epithelium consisted exclusively of necrotic cells. All phases of tubular alterations were seen regularly in each of the biopsies investigated. Germ cells occurred only in phases I-IV and were never observed in tubules in phases V-VII. Significant differences became evident between inguinal and retractile testes by morphometric evaluation. It was demonstrated that the number of germ cells per cross-sectioned tubule (S/T value) correlated negatively with the percentage of tubules in phases V-VII. In contrast to inguinal testes, a complete absence of Sertoli cells and an S/T value less than 0.1 were never found in retractile testes and the percentage of tubules in phases V-VII was reduced significantly compared with inguinal testes. Our findings indicate that (i) maldescended testis in patients between 1 and 15 years-of-age is associated with a special pattern of Sertoli cell degeneration; (ii) Sertoli cell degeneration is a continuous process, which can lead eventually to complete dissolution of the seminiferous epithelium; (iii) total degeneration is not related to age but is dependent on testicular position; (iv) a defined phase of degeneration excludes germ cell development, and therefore enhanced Sertoli cell degeneration in cryptorchid testes must also account for the reduction in germ cell number.

Quantitative and ultrastructural alterations in the lamina propria and Sertoli cells in human cryptorchid testes

A quantitative and ultrastructural study was performed on biopsies of human cryptorchid testes to investigate lesions in the lamina propria and Sertoli cells. Prepubertal cryptorchid testes (1-9 years of age) were classified into four groups: Type 1, testes with minimal lesions; Type II, testes with a moderate decrease in tubule diameter and spermatogonal number; Type III, testes with Sertoli cell hypoplasia and a marked reduction in tubule diameter and spermatogonal number; and Type IV, testes with Sertoli cell hyperplasia and a variable reduction in spermatogonal number. An increase in thickness of the lamina propria was found in Type II and III testes from 5 years of age onwards. These testes also showed a decrease in both the average number of peritubular cells per cross-sectioned tubule and in the average nuclear volume of these cells. Most of the postpubertal cryptorchid testes from 13- to 18-year-old youths presented a prepubertal pattern suggestive of delayed testicular maturation. Postpubertal testes from 19- to 27-year-old men were classified into three types: Type A testes showed complete spermatogenesis, mature Sertoli cells and no lesions in the lamina propria; Type B testes showed isolated spermatogonia, mature Sertoli cells, and a marked thickening of the lamina propria; and Type C testes showed isolated spermatogonia, hyperplasia of immature Sertoli cells, and a slightly thickened lamina propria. Maturation of the lamina propria was always associated with maturation of the Sertoli cells. Thickening of the lamina propria was associated with peritubular cell alterations consisting of decreases in the nuclear volume (average and total per testis) of peritubular cells and increases in the number of these cells per cross-sectioned tubule. The three types of adult cryptorchid testes appear to be the postpubertal transformation of Type 1 testes (Type A), Type II and Type III testes (Type B), and Type IV testes (Type C).

The flow cytometric analysis of undescended testes in children

Flow cytometric analysis was performed on the testicular aspirates of 45 consecutive children with unilateral cryptorchidism undergoing elective orchiopexy or orchiectomy. Concomitant histological analysis was performed on the testicular tissue obtained from either biopsy or orchiectomy specimens. In all cases deoxyribonucleic acid histograms appeared to correspond with microscopic appearance. Histograms from prepubescent patients demonstrated 85 to 95% of cells in the diploid (2c) peak and less than 10% of cells in the tetraploid peak (4c), representing prepubertal testes without active spermatogenesis. Three distinct patterns of ploidy were identified in postpubertal children corresponding to the histological appearances of normal spermatogenesis, maturation arrest and the Sertoli-cell-only syndrome, respectively. In addition, we identified an aneuploid cell population in the specimen from 1 patient, suggesting that this testis may be at risk for future malignant degeneration. We conclude that flow cytometry of testicular aspirates is an easy and effective means of testicular evaluation, which may permit predictions regarding the fertility and malignant potential of undescended testes in postpubertal children.

Ultrastructure of Sertoli cells in cryptorchid goats

Sertoli cells of intra-abdominal testes from 25 naturally occurring, unilaterally cryptorchid, West African pygmy goats between the ages of 1-30 months were morphologically examined by light and transmission electron microscopy. Ultrastructurally, Sertoli cells in the intra-abdominal testes from 1-month-old goats were columnar and contained ovoid nuclei. The cytoplasm depicted clusters of rough endoplasmic reticulum cisternae (RER). In 3- to 4-month-old animals nucleolonemas of the Sertoli cells were associated with vesicles; the cytoplasm contained RER and areas of whorls of smooth endoplasmic reticulum. An abundance of lipid droplets was accompanied by lipofuscin granules in the cytoplasm. In 6- to 8-month-old goats RER cisternae presented circular or irregular profiles in the cells with an augmentation of cytoplasmic lipid droplets and lipofuscin granules. In 12- to 15-month-old animals intercellular spaces in the seminiferous epithelium exhibited focal expansions. Nuclear profiles of the Sertoli cells were irregular. In 24- to 30-month-old animals the Sertoli cells were in an advanced stage of degeneration.

Ultrastructural changes in Sertoli cells in ageing humans

Ultrastructural study of seminiferous tubules in ageing men revealed a varying degree of spermatogenetic arrest associated with changes in the Sertoli cells. Approximately half of the Sertoli cells showed a normal mature nuclear appearance although the cytoplasm was altered morphologically. These cells were classified as containing abundant lipid droplets (30%), containing large cytoplasmic vacuoles filled with an amorphous material similar to that in the tubule lumen and surrounded by junctional specializations (8%), multinucleated Sertoli cells (4%), or Sertoli cells with numerous mitochondria displaying tubular cristae (2%). The remaining 7% of Sertoli cells had an immature nuclear appearance and sparse development of the cytoplasmic organelles; these cells probably represent dedifferentiated Sertoli cells. Although individual differences were marked, a correlation between the increase in gonadotrophin levels and changes in both germ cell development and Sertoli cell structure was observed.