The effects of ligation of vas deferens, corpus epididymidis and vasa efferentia on the testicular function in rats

Morphometric study of the testis and reproductive tract (including sperm granuloma) after vasectomy in mature rats

By utilizing the rabbit model, previous studies have found good evidence indicating that vasectomy-induced spermatogenic damage is pressure-mediated: the damage occurs when the occluded reproductive tract is unable to accommodate additional spermatozoa produced by the testis. More studies with the more commonly used rat model have shown, however, controversial results on whether and why the damage occurs. In this study, 12 mature male Sprague-Dawley rats were subjected to unilateral vasectomy: double ligation (without severing) of the vas deferens exposed via a small inguinal incision; 37 days after the operation, the testes, epididymides, vasa deferentia (juxta-epididymal segments), and sperm granulomas (at the vasectomy site) were removed to obtain methacrylate resin-embedded sections and morphometric studies carried out with light microscopy. Marked spermatogenic damage with spermatids and spermatocytes depleted in the seminiferous epithelium in 43% of the seminiferous tubule profiles was demonstrated in 5 of the 12 testes on the vasectomized side, and the damage was associated with smaller or absent sperm granulomas; in the other 7 testes with essentially normal spermatogenesis, there was an increase (by 111% on average) in the volume of the tubule lumen, associated with larger granulomas or granulomas containing more spermatozoa. There was an overall increase (by 66%) in the thickness of the rete testis in the 12 testes; the epididymis or vas deferens showed no distension. It seems therefore that the spermatogenic damage induced by vasectomy in rats is pressure-mediated as well, and that variation in the damage depends mainly on the postoperative development of the sperm granuloma.

Steroid receptors and their ligands: effects on male gamete functions

In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential.

Efferent duct toxicity with secondary testicular changes in rats following administration of a novel leukotriene A₄ hydrolase inhibitor

The efferent ducts represent an important site of toxicity in the male reproductive tract but are not routinely examined in toxicity studies. This article describes a primary efferent duct toxicity that resulted in secondary testicular changes in rats. Male rats were administered LTI-1, a leukotriene A₄ hydrolase inhibitor, at doses up to 250 mg/kg/d for 3 month or 150 mg/kg/d for 6 month. At the highest dose levels, testicular changes were predominantly unilateral and characterized by diffuse dilation or atrophy of the seminiferous tubules. These testicular changes correlated with granulomatous inflammation in the corresponding efferent ducts, suggesting that the mechanism for the testicular changes involves obstruction and impaired fluid reabsorption in the efferent ducts. Subsequent buildup in fluid volume and back-pressure upstream of the blockage cause dilation of the seminiferous tubules, which, in its late stages, progress to tubular atrophy. There are important differences in efferent duct anatomy between rats and larger mammals, including humans, such that the latter are less susceptible to testicular injury by this mechanism. Because of the limited relevance of this rat-specific finding to humans, it is important to distinguish testicular changes secondary to efferent duct toxicity from primary drug-induced testicular toxicity.

Degeneration of the seminiferous epithelium with ageing is a cause of spermatoceles?

A spermatocele refers to the cystic accumulation of semen in the male reproductive tract. Although it is thought to be caused by narrowing of the lumen of the excurrent duct with resultant cystic dilatation of the duct, the pathogenesis of the narrowing remains unknown. In the present study, we histologically examined spontaneous spermatoceles in C3H/He mice to elucidate the pathogenesis of the lesions. Testes, efferent ducts, epididymides and vas deferens obtained from young and aged C3H/He mice were embedded in plastic for histological observation at the light microscopic level. It was found that spontaneous spermatoceles were localized in the rete testis and efferent ducts of aged mice, as seen in man. The dilated rete testis and efferent ducts contained many degenerated and aggregated germ cells derived from the exfoliated seminiferous epithelium in the aged testis. In particular, it was noted that the agglutinated germ cells obstructed the narrow lumen of the efferent ducts, resulting in the failure of transport of germ cells to the caput epididymis, and spermatoceles were consistently found in the region between the rete testis and the obstructed site in the efferent ducts. However, no inflammatory cell infiltration, traumatic injury or spermatic granulomas were found in the occluded region. These results suggest that agglutinated germ cells may occupy the narrow lumen of the efferent ducts, resulting in the formation of a spermatocele. It may be that a senile change to the seminiferous epithelium, which releases immature germ cells into the lumen of the seminiferous tubules, is the cause of this type of spermatocele.

Effects of vasectomy on the epididymis

Common principles can be discerned in the response of the epididymis to vasectomy, despite species differences. Increases in the size and number of lysosomes are the most frequent changes in the epididymal epithelium. The presence or absence of additional alterations such as changes in the height of the epithelium may be related to variations in distensibility of the vas deferens and epididymis. Direct measurements by micropuncture of epididymal and seminiferous tubule hydrostatic pressure indicate that, contrary to dogma, increased pressure in the distal epididymis after vasectomy is not generally transmitted to the seminiferous tubules. The epididymal interstitium shows microscopic changes indicative of chronic inflammation, with infiltration of macrophages, lymphocytes, and plasma cells, and rats with these lesions have higher antisperm antibody levels than animals lacking epididymal changes. Macrophages and neutrophils may enter the duct through the epididymal epithelium, at sites of rupture of the duct, and in the efferent ductules. Cyst-like spermatic granulomas occur in virtually all species where the epididymis or vas deferens ruptures with escape of spermatozoa. The sites and timing of granuloma formation may depend on the mechanical properties of the tract in different species, and they are probably important in the immune response to vasectomy. Postvasectomy sera in Lewis rats recognize a consensus repertoire of dominant autoantigens that closely resembles the antigens bound by sera from rats immunized with isologous spermatozoa. There are multiple routes for disposal of the sperm that continue to be produced after vasectomy.

Acute effects and long-term sequelae of 1,3-dinitrobenzene on male reproduction in the rat. I. Sperm quality, quantity, and fertilizing ability

Groups of eight adult male rats were given a single oral dose of 0 or 48 mg/kg of 1,3-dinitrobenzene and sacrificed at 1, 2, 4, 8, 16, 24, 32, 72, and 175 days posttreatment. The groups killed at 175 days were bred to untreated females during weeks 3, 4, 6, 9, 13, and 24. Decreased testis weight and testicular sperm numbers were observed by day 4; decreased cauda sperm reserves and epididymis weight occurred by day 8 and day 16, respectively. Reduced numbers of motile spermatozoa and abnormal sperm morphology were seen in spermatozoa from the cauda epididymidis by day 16. Fertilizing ability, as indicated by the presence of two pronuclei and a sperm tail in eggs flushed from the oviducts of inseminated females, was slightly reduced by week 4 and declined to zero by week 6. Group means for reproductive organ weights, sperm production, and sperm reserves failed to return to control levels although some individual animals approached full recovery. Normal fertilizing ability was restored in most animals by week 13, but two of seven remained infertile. Occlusion of some efferent ductules was observed in three of seven animals at 175 days. This study indicates that 1,3-dinitrobenzene is a potent testicular toxicant in the rat, capable of producing marked testicular damage, infertility, and possibly sterility from a single exposure.