Degeneration of the seminiferous epithelium following epididymal obstruction in prepubertal rats

An investigation on cauda storage of sperm in hamster epididymis

Immature testicular sperm of mammals acquire the potential to move in a forward direction during their journey through excurrent ducts, efferent ductules and the epididymis. The present study aimed to determine the sperm storage time using the hamster cauda epididymis. Ligation of the left epididymal tubule at the junction between the distal corpus and the proximal cauda was carried out to determine the storage time. The right epididymis was left unaltered as the control. On days 3, 12, 15, 24, 28, 32, and 40 after ligation of the cauda, experiments were carried out and repeated five times. Sperm total count and mortality were determined using the haemocytometer counting method and sperm viability was assessed with the live/dead viability kit. The morphology of cauda sperm was observed by preparing sperm smears from each animal. Data were analyzed using SPSS and all values were expressed as mean ± SEM. On day 40, the total number of cauda sperms was reduced remarkably. In the experimental groups and in the control, 3–6% of sperm motility was maintained until day 40. By day 3, the percentage of live sperm was 50% and by the 40th day, it was decreased up to 10%. In the control group, the live sperm percentage was 24% by the 40th day (). By day 32, 76% of the cauda spermatozoa appeared abnormal with head defects, mid piece and neck defects and multiple defects. Findings of the present study indicate that cauda sperm storage time is more than 40 days. Motility, viability and morphology of these spermatozoa were decreased remarkably during this storage time.

Meichroacidin containing the membrane occupation and recognition nexus motif is essential for spermatozoa morphogenesis

Meichroacidin (MCA) is a highly hydrophilic protein that contains the membrane occupation and recognition nexus motif. MCA is expressed during the stages of spermatogenesis from pachytene spermatocytes to mature sperm development and is localized in the male meiotic metaphase chromosome and sperm flagellum. MCA sequences are highly conserved in Ciona intestinalis, Cyprinus carpio, and mammals. To investigate the physiological role of MCA, we generated MCA-disrupted mutant mice; homozygous MCA mutant males were infertile, but females were not. Sperm was rarely observed in the caput epididymidis of MCA mutant males. However, little to no difference was seen in testis mass between wild-type and mutant mice. During sperm morphogenesis, elongated spermatids had retarded flagellum formation and might increase phagocytosis by Sertoli cells. Immunohistochemical analysis revealed that MCA interacts with proteins located on the outer dense fibers of the flagellum. The testicular sperm of MCA mutant mice was capable of fertilizing eggs successfully via intracytoplasmic sperm injection and generated healthy progeny. Our results suggest that MCA is essential for sperm flagellum formation and the production of functional sperm.

Postpubertal testicular/epididymal epithelial thickness alterations in unilateral epididymal/vasal obstruction of prepubertal rats

This study was conducted to evaluate postpubertal testicular and epididymal epithelial changes induced by unilateral epididymal and vasal obstruction in rats by measuring epithelium thickness of seminiferous tubuli (MSTet) and epithelium thickness of ductus epididymis (MDEet). Rats were randomly divided into 3 groups: group I underwent unilateral epididymal ligation; group II underwent unilateral vasal ligation and group III received sham operations. MDEet on the ipsilateral side of the epididymal ligation group significantly decreased compared to the contralateral side and sham group. For the contralateral side of the ligated vas, MDEet significantly decreased compared to the ipsilateral side and sham group. MSTet was less on the side of the operation than the contra lateral side and the sham group after both surgical procedures. The obstruction point of the male genital tract affect sperm parameters for clinical extraction or aspiration procedures.

Chronic chromium exposure-induced changes in testicular histoarchitecture are associated with oxidative stress: study in a non-human primate (Macaca radiata Geoffroy)

BACKGROUND

Reproductive toxicity of chromium is in dispute despite positive findings in rodents. Recently we reported epididymal toxicity of hexavalent chromium (CrVI) in bonnet monkeys and in this paper we report its testicular toxicity.

METHODS

Adult monkeys (Macaca radiata) were given drinking water containing CrVI (100, 200, 400 p.p.m.) for 6 months and testes were removed for ultrastructural and biochemical analyses.

RESULTS

CrVI treatment disrupted spermatogenesis, leading to accumulation of prematurely released spermatocytes, spermatids and uni- and multinucleate giant cells in the lumen of seminiferous tubules. Transmission electron microscopy revealed granulation of chromatin and vacuolation between acrosomal cap and manchette microtubules of elongated spermatids and in the Golgi area of round spermatids. Pachytene spermatocytes had fragmented chromatin and swollen mitochondria with collapsed cristae. Spermatocytes and spermatogonia in the basal compartment were unaffected. Macrophages containing phagocytosed sperm and dense inclusions in Sertoli cells were seen. Specific activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase and concentrations of the non-enzymatic antioxidants glutathione, vitamins A, C and E decreased, while concentrations of H(2)O(2) and hydroxyl radicals increased in the testis of chromium-treated monkeys. Withdrawal of chromium treatment for 6 months normalized spermatogenesis and the status of pro- and antioxidants in the testis.

CONCLUSIONS

CrVI disrupts spermatogenesis by inducing free radical toxicity, and supplementation of antioxidant vitamins may be beneficial to the affected subjects.

Elevated steroidogenesis, defective reproductive organs, and infertility in transgenic male mice overexpressing human chorionic gonadotropin

We previously developed a transgenic (TG) mouse model that overexpresses the human chorionic gonadotropin (hCG) beta-subunit under the universal human ubiquitin C promoter, displaying in males a modest 3-fold increase in circulating levels of LH/hCG bioactivity. The males were fertile and presented with a mild reproductive phenotype. To achieve higher levels of hCG, a double TG model was generated by cross-breeding the hCG beta-expressing mice with another TG line harboring a ubiquitin C/common alpha-subunit fusion gene. The double-TG mice expressed excessive levels of dimeric hCG, with 2000-fold elevated circulating LH/hCG bioactivity. These male mice were infertile, primarily due to inability to copulate, and they showed enhanced testicular androgen production despite clear down-regulation of LH/hCG receptors. Their intratesticular inhibin B was unaltered, but serum FSH was markedly reduced. Apparently the chronic hCG hyperstimulation led to focal Leydig cell proliferation/hypertrophy at 6 months of age, but failed to promote testicular tumors. Even though full spermatogenesis occurred in most of the seminiferous tubules, progressive tubule degeneration was apparent as the males grew older. The prostate and seminal vesicles were enlarged by distension of glandular lumina. Functional urethral obstruction was indicated by distension and sperm accumulation in distal vas deferens as well as by dilated urinary bladder and enlarged kidneys. The abnormal function of accessory sex glands and/or lower urinary tract as a consequence of the disturbed sex hormone balance or direct action of hCG may be the main cause of infertility in this model. The present study provides in vivo evidence that exposure of male mice to chronically elevated levels of hCG severely affects their urogenital tract function at multiple sites and causes infertility, but, unlike in LH/hCG overexpressing female mice, it is not tumorigenic.

Pathogenesis of male reproductive tract lesions from gestation through adulthood following in utero exposure to Di(n-butyl) phthalate

Di(n-butyl) phthalate (DBP) acts as an antiandrogen by decreasing fetal testicular testosterone synthesis when male rats are exposed in utero. DBP-exposed male rats develop malformations of the reproductive tract secondary to the reduced fetal androgen levels. However, these malformations and the associated histologic lesions have only been described in adult rats. The objective of this study was to describe the male reproductive tract lesions in fetal, early postnatal, and young adult male rats following DBP exposure in utero. Pregnant Sprague-Dawley rats were exposed to 500 mg/kg/day DBP by gavage on gestation days (GD) 12 to 21. Male reproductive tracts were examined on GD 16 to 21 and on postnatal days (PND) 3, 7, 16, 21, 45, and 70. In the fetal testes, large aggregates of Leydig cells, multinucleated gonocytes, and increased numbers of gonocytes were first detected on GD 17 and increased in incidence to 100% by GD 20 and 21. These lesions resolved during the early postnatal period, while decreased numbers of spermatocytes were noted on PND 16 and 21. On PND 45, there was mild degeneration of the seminiferous epithelium, which progressed to severe seminiferous epithelial degeneration on PND 70. On PND 70, the degeneration was concurrent with ipsilateral malformed epididymides, which caused obstruction of testicular fluid flow and secondary pressure atrophy in the seminiferous tubules. In the fetus, the epididymal lesion was observed as decreased coiling of the epididymal duct. The decreased coiling progressed into the early postnatal period and adulthood, at which time malformed epididymides were apparent. As the animals were only dosed in utero, these findings indicate that DBP can initiate fetal testicular and epididymal changes that may not manifest as clear malformations until adulthood. The pathogenesis of lesion development from the fetus to the adult is important for comparison of antiandrogens with differing modes of action.

Histopathological examination of both ipsilateral and contralateral testes with different obstructive models in prepubertal and adult rats

OBJECTIVE

To determine the histopathological changes in both the ipsilateral and contralateral testes of prepubertal and adult male rats 60 days after creating different obstructive models.

MATERIAL AND METHODS

Thirty-six prepubertal and 32 adult albino male rats were examined in three different obstructive models of the right testis. In group 1 the spermatic cord was ligated, in group 2 the ligation was between the caput epididymis and testis, and in group 3 the vas deferens was ligated. Sixty days after ligation both testes were removed and evaluated for testis diameter, mean seminiferous tubule diameter (MSTD), and degenerative, obstructive and inflammatory changes.

RESULTS

The diameter of the obstructed right testis and MSTD were significantly greater in prepubertal rats but there was no apparent difference in adult rats. For obstructive changes, sloughing of germ cells in the prepubertal rats and germ cell absence in adult rats were significantly more common in group 3. The contralateral testis diameter and MSTD of group 3 was significantly greater only in prepubertal rats. Statistically significant values of obstructive change, e.g. sloughing of germ cells and apical vacuolation in Sertoli cells, were apparent in prepubertal rats, but tubular ectasis was the only statistically significant criterion of obstruction in adult rats.

CONCLUSION

The testes are more susceptible to obstruction of the vas deferens in prepubertal than in adults rats, resulting in increased hydrostatic pressure and oedema of both the ipsilateral and contralateral testes, which might be caused by collateral circulation and rat testicular microcirculation, with a rhythmic pattern of arteriolar dilatation and constriction (vasomotion). Although the presence of oedema and high hydrostatic pressure was not prominent in adults, formation of spermatic granulomas and absence or sloughing of germ cells in the obstructed and contralateral testes reflect the early effects of vas ligation on spermatogenesis in adulthood.

Effects of in utero exposure to linuron on androgen-dependent reproductive development in the male Crl:CD(SD)BR rat

Linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) is a herbicide that blocks androgen action in the male rat. Studies were undertaken to characterize the ability of linuron to activate transcription through the human androgen receptor (AR) in vitro and to determine whether in utero linuron exposure induces dose-responsive alterations in androgen-dependent reproductive development in the male rat. In vitro, linuron competitively antagonized transcriptional activity of the AR induced by dihydrotestosterone (DHT) in a dose-responsive manner with an equilibrium dissociation constant (K(B)) of 75.8 x 10(-8) M. Pregnant rats were administered linuron by gavage at 0, 12.5, 25, or 50 mg/kg/day (n = 11/group) from gestation day 12 to 21. Anogenital distance of resulting offspring was unaffected, whereas male areola/nipple retention was increased in a dose-responsive manner. Hypoplastic testes in adult offspring were seen in 2/56 rats (2/10 litters), 8/69 rats (4/11 litters), and 5/44 rats (3/8 litters), while hypoplastic epididymides occurred in 1/56 rats (1/10 litters), 8/69 rats (4/11 litters), and 2/44 rats (1/8 litters) in the 12.5, 25, and 50 mg/kg/day dose groups, respectively. Partial agenesis of the epididymides was observed in 3/44 rats (2/8 litters) only in the 50 mg/kg/day group. These data indicate that in utero exposure to linuron preferentially impairs testosterone-mediated, rather than DHT-mediated, reproductive development. This effect is distinctly different from the effects induced by flutamide, an AR antagonist that shares structural similarities with linuron. Furthermore, these data suggest that dose-response studies utilizing late gestational exposure to endocrine-active compounds may be more robust than the traditional or EPA-modified multigeneration protocols in identifying adverse effects.