Unilateral Vasectomy Research Articles

Unilateral vasectomy for intractable epididiymo-orchitis in patients with anorectal malformation

Male patients treated for anorectal malformations (ARM) and recto-urethral fistula (RUF) tend to develop recurrent epididymo-orchitis (EO) which occurs approximately in 20% of all them. The optimal management of this condition is unclear because of the extreme its rarity and the unavailability of detailed analysis in literature. To date the majority of this patients benefits from medical treatment and symptoms reduce over time but few data have been published in literature about management of patients with intractable EO. To describe the efficacy of unilateral vasectomy in patients operated on for anorectal malformations with RUF and affected by intractable EO. We present five patients who met the criteria for intractable EO, and followed at our centre four of whom have undergone unilateral vasectomy. The first episode of EO presented at 42,00mos±29.39. Initially, patients were all managed with analgesics and antibiotics. For the failure of therapy, five patients were all offered unilateral vasectomy but only four families accepted procedure. Surgical treatment was performed as a day case without complications. Postoperative follow up was 88,50mos±68.36. Prompt and durable resolution of symptoms was observed. The long-term effects of recurrent EO in ARM are often underestimated. Prompt and appropriate intervention should prevent this undesirable sequela. Unfortunately, the optimal management of this complication is unclear, partly because of its extreme rarity. The established management needs to follow the route of correcting underlying anomalies and providing long-term analgesic and antibiotics but this may have undesired side effects. We therefore offered families vasectomy for complete symptom resolution and/or drug withdrawal. Vasectomy, as a form of treatment for, can be justified if it can prevent pain, infection and destruction of the testes. Early vasectomy may save enough functional testis tissue. To date, the only available treatment to achieve definitive resolution of symptoms in intractable unilateral EO is vasectomy. Long-term effects of such procedure on fertility are unknown. The treatment of recurrent EO in cases without site predilection remains a matter of contention.

A Stereological (Quantitative) Study of Leydig Cell Hyperplasia in Vasectomized Rabbit and Rat Testes

It was speculated that vasectomy might induce hyperplasia of Leydig cells associated with atrophy of seminiferous tubules, but estimates of the Leydig cell number were lacking in previous studies. This study aimed to test the speculation by determining the numerical change of Leydig cells and other interstitial cells after a vasectomy that induced spermatogenic damage. Twelve adult Japanese white rabbits and twelve mature Sprague-Dawley rats were subjected to a unilateral vasectomy away from the scrotum. Six months (rabbits) or thirty-seven days (rats) postoperation, testes on both sides were removed and methacrylate sections prepared. The total numbers (per testis) of all nuclei in the testicular interstitial tissue were estimated with a stereological technique – the optical disector. The results showed that marked spermatogenic damage associated seminiferous tubular atrophy on the vasectomized side occurred in 7 (rabbits) or 5 (rats) of the 12 animals. For the rabbit, the total numbers of myoid cells or leukocytes on the vasectomized side (compared with the contralateral nonvasectomized side) were unchanged but those of Leydig cells and other interstitial cells increased significantly by 41% and 52%, respectively, (a) with the increase in the testis with spermatogenic damage appearing to be larger than that in the testis without spermatogenic damage and (b) without significant increase in the total volume of the interstitium. For the rat, there were no significant differences in the total numbers of any cell type. In conclusion, hyperplasia or hyperproliferation of the interstitial cells, which might be a result of increased intra-testicular pressure for long, was possible postvasectomy, but it might not be indicative of a better function of the cells.

Comperative Investigation of Structure of Male Genital System of Ductus Deferens Ligation in Rats

Objective: We investigated structural and morphological changes in pre-pubertal and pubertal rat testis and ductus deferens after unilateral vasectomy. Vasectomy is reliable and popular male contraception method, applied widely in the world. Methods: Six pre-pubertal and 6 pubertal male Wistar albino rats were divided into four groups. Unilateral ductus deferens ligation was performed on right ductus deferens of each rat. Right testis and ductus deferens tissues were evaluated as ligation group while left tissues were control groups. Two months after operation, the vas deferens and testes removed to obtain paraffin block sections and morphometric studies carried out with light microscopy. Hematoxylin-eosin staining and vascular endothelial growth factor (VEGF) immunohistochemically staining were applied. Results: Structural and morphological changes and decrease in spermatogenesis process have been observed at testis and ductus deferens tissues of all vasectomized rat. The seminiferous epithelium and the seminiferous tubule diameter were thickened. Degenerative changes have been observed at the epithelial structure of Ductus deferens and among muscle fibers forming the muscle of the Ductus deferens. Moreover, in pre-pubertal and pubertal vasectomized rat VEGF immunoreactivity was not observed in seminiferous tubule. Conclusion: The unilateral ligation operation can cause damage at ductus deferens and testis tissue in the pre-pubertal and pubertal period.

Unilateral absence of vas deferens: prevalence among 23.013 men seeking vasectomy.

ABSTRACTPurpose:To determine the prevalence of unilateral absence of vas deferens (UAVD) in men with both testes seeking vasectomy.Materials and Methods:Computerized charts of 23,013 patients encountered between January 1994 and December 2013 in one university hospital and two community clinics of Quebec City, Canada, were searched. Pre-vasectomy consultation, operative reports and semen analysis results were reviewed to identify cases of UAVD. Cases were categorized as confirmed (unilateral vasectomy and success confirmed by semen analysis) or possible congenital UAVD further sub-categorized according to whether or not a scrotal anomaly was present.Results:Among 159 men identified as potentially having UAVD, chart review revealed that 47 had only one testicle, 26 had bilateral vasa, and four were misdiagnosed (post-vasectomy semen analysis [PVSA] showing motile sperm after unilateral vasectomy) leaving 82 men deemed cases of UAVD (0.36%, 95% confidence interval 0.28% to 0.43%). These were classified as confirmed (n=48, 0.21%) and possible (n=34, 0.15%; 22 without and 12 with scrotal anomalies) congenital UAVD. The misdiagnosis ratio of UAVD was low when scrotal content was otherwise normal (1:48), but higher if anomalies were present (3:12).Conclusions:Most surgeons who perform vasectomy will encounter cases of UAVD. In most suspected cases, it is safe and effective to proceed with unilateral vasectomy under local anesthesia while stressing the need for PVSA. Further studies or scrotal exploration may be considered in patient with prior scrotal surgery.

Fertilization defects in sperm from Cysteine-rich secretory protein 2 (Crisp2) knockout mice: implications for fertility disorders.

We hypothesize that fertility disorders in patients with aberrant expression of Cysteine-RIch Secretory Protein 2 (CRISP2) could be linked to the proposed functional role of this protein in fertilization. Our in vivo and in vitro observations reveal that Crisp2-knockout mice exhibit significant defects in fertility-associated parameters under demanding conditions, as well as deficiencies in sperm fertilizing ability, hyperactivation development and intracellular Ca(2+) regulation. Testicular CRISP2 is present in mature sperm and has been proposed to participate in gamete fusion in both humans and rodents. Interestingly, evidence in humans shows that aberrant expression of CRISP2 is associated with male infertility. A mouse line carrying a deletion in the sixth exon of the Crisp2 gene was generated. The analyses of the reproductive phenotype of Crisp2(-/-) adult males included the evaluation of their fertility before and after being subjected to unilateral vasectomy, in vivo fertilization rates obtained after mating with either estrus or superovulated females, in vitro sperm fertilizing ability and different sperm functional parameters associated with capacitation such as tyrosine phosphorylation (by western blot), acrosome reaction (by Coomassie Blue staining), hyperactivation (by computer-assisted sperm analysis) and intracellular Ca(2+) levels (by flow cytometry). Crisp2(-/-) males presented normal fertility and in vivo fertilization rates when mated with estrus females. However, the mutant mice showed clear defects in those reproductive parameters compared with controls under more demanding conditions, i.e. when subjected to unilateral vasectomy to reduce the number of ejaculated sperm (n = 5; P< 0.05), or when mated with hormone-treated females containing a high number of eggs in the ampulla (n ≥ 5; P< 0.01). In vitro fertilization studies revealed that Crisp2(-/-) sperm exhibited deficiencies to penetrate the egg vestments (i.e. cumulus oophorus and zona pellucida) and to fuse with the egg (n ≥ 6; P< 0.01). Consistent with this, Crisp2-null sperm showed lower levels of hyperactivation (n = 7; P< 0.05), a vigorous motility required for penetration of the egg coats, as well as a dysregulation in intracellular Ca(2+) levels associated with capacitation (n = 5; P< 0.001). The analysis of the possible mechanisms involved in fertility disorders in men with abnormal expression of CRISP2 was carried out in Crisp2 knockout mice due to the ethical and technical problems inherent to the use of human gametes for fertilization studies. Our findings in mice showing that Crisp2(-/-) males exhibit fertility and fertilization defects under demanding conditions support fertilization defects in sperm as a mechanism underlying infertility in men with aberrant expression of CRISP2. Moreover, our observations in mice resemble the situation in humans where fertility disorders can or cannot be detected depending on the accumulation of own individual defects or the fertility status of the partner. Finally, the fact that reproductive defects in mice are masked by conventional mating highlights the need of using different experimental approaches to analyze male fertility. This study was supported by the World Health Organization (H9/TSA/037), the National Research Council of Argentina (PIP 2009-290), the National Agency for Scientific and Technological Promotion of Argentina (PICT 2011, 2023) and the Rene Baron Foundation to P.S.C. and by the MEXT of Japan to M.I. The authors declare that there are no conflicts of interest.

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.

Long-term study of vasectomy in Macaca radiata – histological and ultrasonographic analysis of testis and duct system

This study was aimed to investigate the long-term effect of vasectomy using the bonnet monkey (Macaca radiata) as a primate animal model. Animals weighing around 6 to 8 kg were randomly chosen for bilateral, unilateral vasectomy and sham-control. The postoperative periods of six months and two years were considered as short and long-term, respectively. Sperm were collected and subjected to analysis before euthanasia. The testes and epididymides were excised from euthanized animals then embedded in paraffin. Normal histological changes were observed in sham-operated animals and short-term contralateral testes. In contrast, marked alterations were observed in the testes and epididymides of both short and long-term groups. Seminiferous epithelium was thinned out showing marked depletion of germ cells in long-term; only a thin layer of Sertoli cells, spermatogonia, and fewer spermatocytes were seen. Exfoliation of germ cells and the occurrence of multinucleated giant cells were common features in these tubules. The epididymal tubular lumens were greatly dilated with accumulated spermatozoa in short and long-term animals; significant defects were observed in the epithelium of the long-term animals. Microscopic spermatic granulomas were noticed in epididymides and the vas deferens. Large granulomas were seen in long-term vasectomized monkeys, frequently compressing the surrounding structures. These granulomas could be visualized in ultrasound, however, only at the late stage of its occurrence. Sperm collected from the unilateral vasectomized animals showed a poor motility score in the capillary mucus penetration test (CMPT). Results indicate that the changes observed after vasectomy might be due to pressure initially, whereas in the long-term the damage was supplemented by autoimmune attack. With immunoglobulin (IgG) deposition in contra-lateral unoperated testis of unilateral vasectomized animals it also showed degenerative changes and a concomitant drop in sperm quality. Although, granulomatous reactions were observed in the epididymis and vas deferens but testes were spared from such reactions even in the long-term.

Regulatory T cells and vasectomy

CD4+ CD25+ regulatory T cells (Tregs) strongly influence the early and late autoimmune responses to meiotic germ cell antigens (MGCA) and the gonadal immunopathology in vasectomized mice. This is supported by the published and recently acquired information presented here. Within 24h of unilateral vasectomy (uni-vx) the ipsilateral epididymis undergoes epithelial cell apoptosis followed by necrosis, severe inflammation, and granuloma formation. Unexpectedly, vasectomy alone induced MGCA-specific tolerance. In contrast, uni-vx plus simultaneous Treg depletion resulted in MGCA-specific autoimmune response and bilateral autoimmune orchitis. Both tolerance and autoimmunity were strictly linked to the early epididymal injury. We now discovered that testicular autoimmunity in uni-vx mice did not occur when Treg depletion was delayed by one week. Remarkably, this delayed Treg depletion also prevented tolerance induction. Therefore, tolerance depends on a rapid de novo Treg response to MGCA exposed after vasectomy. Moreover, tolerance was blunted in mice genetically deficient in PD-1 ligand, suggesting the involvement of induced Treg. We conclude that pre-existing natural Treg prevents post-vasectomy autoimmunity, whereas vasectomy-induced Treg maintains post-vasectomy tolerance. We further discovered that vasectomized mice were still resistant to autoimmune orchitis induction for at least 12–16 months; thus, tolerance is long-lasting. Although significant sperm autoantibodies of low titers became detectable in uni-vx mice at 7 months, the antibody titers fluctuated over time, suggesting a dynamic “balance” between the autoimmune and tolerance states. Finally, we observed severe epididymal fibrosis and hypo-spermatogenesis at 12 months after uni-vx: findings of highly critical clinical significance.

The effect of unilateral vasectomy on testosterone and testicular parameters in the adult male African giant rat (Cricetomys gambianus)

The effects of vasectomy on spermatogenesis and reproductive parameters are recognized to be specie-dependent with marked differences in levels of perturbations observed. To assess the impact of unilateral vasectomy on testosterone level and other testicular parameters in the male African giant rat (AGR) (Cricetomys gambianus). Sixteen adult male AGRs weighing 500-1300 g were recruited for the experiment. Animals were randomly divided into three experimental groups (1-3) and one control (sham operated) group with four rats per group. Experimental vasectomy was done by carefully ligating the vas deferens of the right testis of all the experimental groups (1, 2, and 3) and animals were allowed either 8, 6 and 2 weeks respectively before sacrifice. Sham-operated animals served as the control. Blood samples were collected and assayed for testosterone while testicular tissue was further processed for seminal fluid and histo-pathological analyses. Spermatogenic parameters indicate a pattern of decline in sperm count and motility between the experimental groups and the control and azoospermia in the eight-week group. Histological alterations were marked by atrophy of seminiferous tubules which was proportional to the duration of vasectomy. Serum testosterone levels were significantly reduced at eight weeks. There was no statistically significant difference between sperm counts of right and left testes except for group 3. Results suggest that unilateral vasectomy of the AGR may have negative impact on the contralateral testis in the male African giant rat. These preliminary results reveal that unilateral vasectomy in the AGR may result in perturbations of the histo-architecture of the testes with possible decline in function.

Survivin Downregulation Is Associated with Vasectomy-Induced Spermatogenic Damage and Apoptosis

Objective: To evaluate the expression of the apoptotic genes survivin, Bax and Bcl-2 in vasectomized rabbits and to determine their relation with vasectomy-induced spermatogenic impairment and germ cell apoptosis. Materials and Methods: Twelve adult rabbits (6–12 months old) were divided into three groups: sham control, unilateral vasectomy or bilateral vasectomy. Six months after vasectomy, testicular tissue was analyzed for germ cell apoptosis and DNA fragmentation by the TUNEL assay and gel electrophoresis, respectively. Spermatogenesis was assessed using the Johnsen score. The relative gene expression of survivin, Bax and Bcl-2 was measured using reverse transcription followed by real-time PCR. Results: Compared to sham animals, a significant decrease in testicular survivin mRNA levels was measured in the two vasectomy animal groups (p < 0.05). This was accompanied by a significant increase in the Bax:Bcl-2 ratio in the vasectomized animals (p < 0.05). In addition, these data showed positive correlation with enhanced apoptotic index, damage to spermatogenesis and DNA fragmentation after vasectomy. Conclusion: These findings demonstrate that vasectomy-induced damage to spermatogenesis due to testicular apoptosis may be associated with survivin downregulation and Bax overexpression.

Effect of unilateral vasectomy, epididymectomy and epididymal ligation on the reproductive capacity of growing rams.

Effect of unilateral vasectomy, epididymectomy and epididymal ligation on the reproductive capacity of growing rams.

Effects of Chemical Sympathectomy on Contralateral Testicular Histology and Fertility in Unilateral Vasectomy

Unilateral obstruction or injury to the vas deferens can result in significant injury to the contralateral testicle. Although various pathways have been proposed, the mechanism of contralateral testicular deterioration remains controversial. The present animal study was performed to evaluate the effects of unilateral vasectomy on ipsilateral and contralateral testicular histology and fertility in rats that were chemically sympathectomized neonatally. The study comprised 40 male albino rats: 20 received a placebo and the other 20 underwent chemical sympathectomy neonatally. When 60 days old, each group of 20 rats was divided into two groups that underwent either a sham operation or an operation to create unilateral left vasectomy. Eight weeks after surgery, each male rat was housed with two known fertile female rats for 25 days, and then their testes were harvested. Mean seminiferous tubular diameters (MSTD) and mean testicular biopsy scores (MTBS) were determined for each testis. Although MSTD and MTBS were not significantly different between groups, chemical sympathectomy prevented the decrease in total fertility rates of the rats with unilateral left vasectomy in our study. Prevention of this decrease by chemical sympathectomy suggests that the sympathetic nervous system may play a role in the testicular degeneration associated with vasectomy.

Clinical, ultrasonographic and pathological features following unilateral vasectomy in rams

The effects of vasectomy on testes and related structures of animal species and men are largely disputable. These possible effects were studied in the ram, an established experimental animal model used to investigate genitalia pathophysiology. In each of five rams, vasectomy in the left spermatic cord was carried out; subsequently, the clinical and ultrasonographic features were monitored up to 12 months post-operatively. The rams were sequentially euthanatized 1, 3, 6, 9 and 12 months post-operatively; gross- and histo-pathological examination of their testes and related structures were carried out. Four of the five rams developed sperm granulomas at the proximal to the testis end of vas deferens or/and at the tail of the epididymis; these were palpable from the first and the third month after vasectomy, respectively. Ultrasonographic findings on the vasectomy side were increased size and echogenicity of the epididymal tail, as well as anechoic areas, representing sperm granulomas, visible in the epididymal tail 1 week after vasectomy and in the proximal to the testis end of vas deferens 4 weeks after vasectomy. Gross pathological findings were limited on the vasectomy side and included adhesions between the parietal and the visceral vaginal tunic, enlarged and firm epididymal tail and presence of sperm granulomas at the epididymal tail or/and at the proximal to the testis end of vas deferens; the granulomas contained creamy material. Histopathological changes were observed mainly in the epididymal tails, consisting of a central mass of spermatozoa, surrounded by a layer of macrophages, surrounded in turn by loose vascular connective tissue rich in lymphocytes and plasma cells. With the exception of signs of mild hypospermatogenesis observed in one ram euthanatized 9 months after surgery, and of a slight increase in seminiferous tubule diameter and in seminiferous epithelium height in the rams euthanatized 6 and 9 months after surgery, which are both findings of no clinical importance, no clinical, ultrasonographic, gross- or other histo-pathological changes were observed in the testicular parenchyma during a 12-month post-operative period. These results demonstrate that vasectomy has little if any detrimental effect on the morphologic characteristics of the spermatogenesis in rams.

Influence of orchidopexy for cryptorchidism on subsequent fertility.

The concentration of spermatozoa in ejaculate from testes that had been subjected to orchidopexy during childhood was studied in semen samples taken after unilateral vasectomy of the contralateral normal testis in 4 patients. The counts were extremely low, which suggests that this operation does not improve fertility later in life. Sperm concentration is not influenced by unilateral vasectomy or by inguinal herniotomy during childhood.

Correspondence

In the August 2004 issue of Journal of Anatomy, Kong and colleagues reported that unilateral vasectomy in rabbits resulted in ipsilateral (‘vasectomy-induced’) damage to spermatogenesis – most severely at 10 days (in all testes), and less severe in about half the testes at 6 and 12 months. This testis-damaging effect of vasectomy contrasts with their previous results in the rhesus monkey in which the testes showed no such damage. Because of an interest in the keratinoid tough quality of mammalian sperm, and how they are disposed of after vasectomy (and because of the importance of vasectomy in humans), in the mid-1970s I studied this question in the rhesus monkey, hamster, rat and rabbit (Bedford, 1976). After vasectomy in these animals spermatogenesis usually continued normally. However, sperm accumulation brought a rupture at one or more focal points in the lower epididymis or vas deferens within a few weeks in the monkey, hamster and rat – but with the rabbit as a notable exception. Apparently because of the relatively elastic distensible quality of the lower duct in the rabbit, the accumulating sperm simply produced an increasing distension or dilatation of its vas deferens and cauda epididymidis, with little or no change in the upper epididymis. As this distal accumulation and distension progressed over the next months the intact rabbit cauda epididymdis and vas became relatively huge until, beginning at about 6 months after vasectomy, some ducts ruptured focally and formed granulomata (sperm disposal sites). In order to quantify this situation, Moore & Bedford (1978) counted the sperm total accumulating at 1, 2, 4 and 6 months after vasectomy. Somewhat surprisingly even to us, after vasectomy the number of spermatozoa accumulating in the distensible epididymis/vas at each time period was equivalent to the total that would be produced by a normal testis over the same time period – in other words, after vasectomy spermatogenesis had continued at a normal rate over a 6-month period in the rabbit. In both our studies the rabbit testicular weights (one sensitive indicator of function) were similar on the vasectomized and control sides, with the notable exception of occasional animals in which a granuloma had formed high in the epididymis. Regrettably, the conclusion of Kong et al. that vasectomy in the rabbit soon results in testicular damage is incorrect, and the pattern of their own results reinforces this view. The fact that the greatest testicular damage was seen in their study after only 10 days, when sperm accumulation is minimal, suggests that the damage may have resulted not from vasectomy per se but from local trauma or inflammation. This will occur quite readily after exposure of the vas deferens by incision of the skin and processus vaginalis of the rabbit scrotum, rather than via one small central incision in the high inguinal region. Since Kong et al. (2004) quote Bedford (1976) in explaining the testicular damage, it is puzzling that they do not comment also on the very different pattern of the respective results.

Quantitative (stereological) study of the effects of vasectomy on spermatogenesis in rabbits.

Using stereological methods, especially the optical disector for unbiased estimation of nuclear number, our recent study demonstrated that long-term (6 or 12 months) vasectomy in the rhesus monkey had no significant effects on spermatogenesis (Peng et al. Reproduction 2002, 124, 847-856). This study aimed to determine the scenario in the rabbit using the same morphometric methodology. Three groups of normal male Japanese white rabbits (aged 4-5 months) were subjected to unilateral vasectomy; 10 days, 6 months and 12 months later both testes and epididymides were removed. Testicular and epididymal methacrylate-embedded sections were obtained for stereology. Vasectomy-induced damage to spermatogenesis was observed, primarily sloughing of spermatogenic cells with a greater reduction in the number of advanced (adluminal) cells. The damage was most severe at 10 days, occurring in all the testes on the vasectomized side and involving sloughing of even type A spermatogonia, the number of which returned to normal at 6 and 12 months. Damage was less severe at 6 and 12 months, being found in half of the testes of the vasectomy side, in which the total numbers of later germ cell types were 24.0-59.1% (spermatocytes) and 0.3-11.6% (spermatids) of control at 6 months, and 20.1-22.1% (spermatocytes) and 0.4-12.0% (spermatids) of control at 12 months. By contrast, Sertoli cell number per testis was unchanged following vasectomy in any group. Epididymis on the vasectomy side, especially at 10 days and 6 months, appeared larger than on the contralateral side, but this difference was not statistically significant, and no sperm granuloma was seen in the epididymis.

The use of URYX for reversible vasectomy in a rabbit model.

URYX is a biocompatible polymer of ethylene vinyl alcohol dissolved in a dimethyl sulfoxide (DMSO) carrier to allow injection of a very low-viscosity fluid into tissue. Once the material comes into contact with body tissue or fluid, the DMSO rapidly dissipates from the polymer, which results in a precipitate of a coherent solid mass. The purpose of the present study was to determine whether URYX can effectively occlude the vas deferens and whether patency can be restored by redissolving the URYX in vivo using the solvent DMSO. Eight male New Zealand White rabbits (age range, 25-41 weeks; mean age, 33.9 +/- 7.5 weeks; mean weight, 4.0 +/- 0.2 kg) were used in 2 experiments (E1 and E2). In E1, 3 rabbits underwent unilateral vasectomy, and the contralateral vas was injected with either 0.05 or 0.10 mL of URYX, to determine the amount of URYX required to cause obstruction. Two animals underwent bilateral vasectomy, to serve as controls. In E2, 3 animals underwent bilateral URYX injection and were compared with the bilateral vasectomy control rabbits used in E1. After 1 month of initial bilateral URYX treatment, all animals in E2 underwent attempted unilateral reversal with 1.5 mL of DMSO injected into 1 occluded vas deferens. Two end points were evaluated-a clinical end point assessed by semen analyses and a pathological end point assessed by histological analysis of treated tissues, to assess for safety. A 1.5-cm infrapubic incision was made to expose both vasa in anesthetized rabbits. The vasal injection of URYX was performed with a 30-gauge needle. Vasectomy was performed by excision of a 1-cm segment of the vas deferens and subsequent ligation with a 6-0 prolene suture. Semen was collected using an artificial vagina 2-3 times/wk before and 1 month later, after injection treatments and vasectomy. Manual sperm counts were performed. All animals were sacrificed, and tissues (distal vas, injection site, proximal vas, cauda epididymis, caput epididymis, and testis) were harvested and examined for the presence of URYX. The inflammatory response of the wall and adventitia of the vas deferens was given a score (0-15) based on the sum of grades (0 = none, 1 = mild, 2 = moderate, and 3 = severe) for the following categories: foreign body giant cell reaction, granulation tissue, lymphocytes, eosinophils, and scarring, as evaluated by a single pathologist (J.M.). Vasal injection with 0.05 mL of URYX was not sufficient to cause occlusion. Both animals injected with 0.1 mL of URYX were effectively occluded. The injection of occluded vasa with DMSO did not dissolve the URYX plug in the vas lumen. There was no significant difference in vasal inflammatory response scores between vasal units treated with URYX only and vasal units in the vasectomy model. Vasal units subjected to URYX followed by DMSO demonstrated greater inflammatory response scores than vasal units treated with URYX followed by normal saline, URYX alone, or vasectomy. Epididymal and testicular histology remained unaffected in all vasal units in E1. The vasal units in E2 subjected to URYX followed by normal saline showed no histological abnormalities of the epididymis and testis. However, those vasal units subjected to URYX followed by DMSO in E2 showed evidence of adhesions, necrosis, and degenerating cells in the epididymis and a focal foreign body giant cell reaction in the testis. The bilateral vasal injection of URYX can result in azoospermia in the rabbit model. Reversal with subsequent DMSO injection was not achieved. A minimal inflammatory response of the vas deferens was observed with URYX injection alone; however, DMSO following URYX injection resulted in increased vasal inflammation, in addition to epididymal and testicular changes.

Antisperm autoantibody response after unilateral vas deferens ligation in rats: when does it develop?

Unilateral obstruction or injury to the vas deferens can result in significant injury to the contralateral testicle. Antisperm autoantibodies are thought to play a significant role in this phenomenon. It has been reported that early surgical repair of the vas, before the development of antisperm autoantibodies, will prevent any potential damage to the contralateral testicle. This led us to investigate the timing of the antisperm antibody production and to attempt to determine whether antibody production precedes histologic testicular damage in the Lewis rat model. In a controlled study, mature rats were divided into temporal groups, with the experimental animals all receiving a unilateral vasectomy. At postoperative endpoints of 1, 7, 15, or 30 days, blood samples were collected for immunologic assay, and the testicles were harvested for histologic examination. Antibody levels were measured by an immunobead test using goat anti-rat immunoglobulin G (IgG)-coated Sepharose beads; tissue sections were fixed in Bouin solution, embedded in paraffin, and stained with hematoxylin and eosin. There was no statistically significant histologic difference between any of the groups. However, immunologic evaluation revealed a statistically significant increase in immunobead antibody binding in the 30-day group compared to the control groups (P = .02). These data seem to indicate that in this model, antisperm antibody production is not evident until 15-30 days after unilateral injury to the vas deferens occurs, and the development of these antibodies precedes any demonstrable histologic damage to the testicle. If it is correct to infer that human antisperm antibody production will also precede histologic testicular damage, and further, that the onset of the human autoantibody response may vary from several days to weeks, then in cases of suspected or known ductal injury, the clinical monitoring of antisperm antibody levels could enable testicular damage to be predicted prior to its development and thus be avoided.

A study on the mechanism of the spermatogenic damage after vasectomy in rats

Vasectomy may result in damage to spermatogenesis. There are several explanations for this damage, including an increase of pressure in the seminiferous tubules and an autoimmune reaction. Recently, vasectomy has been reported to induce germ cell death by apoptosis. However, the exact mechanism of this vasectomy-induced germ cell apoptosis is unclear. To elucidate this mechanism, we designed a vasectomized rat model and examined the testiscular alterations and apoptotic degeneration biochemically and microhistopathologically. Particularly, we analyzed the expression of nitric oxide synthase (NOS) and nuclear factor kappa B (NF kappa B), which plays a critical role in the induction of the iNOS gene, in the testis after vasectomy to gain insight into the association between germ cell apoptosis and these factors. The testes of 40 Wistar rats (10-weeks old) were studied at 1, 2, 5 and 10 weeks after unilateral (left) vasectomy. Wistar rats weighting 290 to 310 g were divided into 2 groups and subjected to underwent either unilateral vasectomy or sham surgery under ether anesthesia. Bilateral testes were carefully observed biochemically and histopathologically. Apoptosis was detected by an in situ end-labeling technique (detection of cellular DNA fragmentation) and electron microscopy. Neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS) protein was detected by Western blotting and immunohistochemical studies using each NOS monoclonal antibody. To confirm the co-localization of cellular DNA fragmentation in germ cells and each NOS, each set of consecutive testis sections (one stained for cellular DNA fragmentation and the others for each NOS) were examined. Expression of NF kappa B proteins was examined immunohistochemically using a NF kappa B p65 polyclonal antibody. At 5 and 10 weeks after vasectomy, the vasectomized left testis was significantly lighter than the unvasectomized right testis and sham-operated testis. At that time, the seminiferous tubules of vasectomized testes were highly damaged, presenting narrow tubular diameter, disorder of cellular arrangement, depletion of the germ cells, and local interstitial fibrosis. Vasectomized testes demonstrated a significantly increased number of apoptotic germ cells per cross-sectional area compared with sham-operated testes at 5 and 10 weeks after operation (p < 0.01). Electron microscopy revealed apoptotic germ cells each with a darkly stained nucleus. Western blotting and immunohistochemical studies demonstrated that iNOS proteins were more strongly expressed on vasectomized testes as time passed after vasectomy. Examination of consecutive sections from the vasectomized testis revealed that visibly apoptotic germ cells that exhibited positive staining for cellular DNA fragmentation were also intensely stained for eNOS and iNOS. NF kappa B p65 proteins were more strongly expressed in the nucleus of germ cells in the vasectomized testis than in the sham-operated testis. We found that vasectomy results in damage to spermatogenesis in adult rats, that may induce germ cell apoptosis, and that iNOS and NF kappa B may play a critical role in the germ cell apoptosis after vasectomy.

Effect of vasovasostomy on contralateral testicular damage associated with unilateral vasectomy in mature and immature Lewis rats

Objective: We sought to determine if laser-assisted vasovasostomy could reverse the contralateral histologic testicular changes associated with unilateral vasectomy. Design: A prospective, randomized, blinded, controlled study. Setting: Animal microsurgical laboratory, St. John’s Mercy Medical Center, St. Louis, Missouri. Patient(s): Twenty mature and 20 immature male Lewis rats. Intervention(s): Ten mature and 10 immature male Lewis rats underwent unilateral vasectomy. At 5 months, testicular biopsy and laser-assisted vasovasostomies were performed followed 2 months later by evaluation of vas patency and repeat testicular biopsy. Control animals consisted of 10 rats in each group, 5 that underwent sham operations and 5 that had halothane anesthesia alone. Result(s): In the immature and mature groups unilateral vasectomy resulted in marked contralateral testicular damage in 30% (3 of 10) and 50% (5 of 10), respectively. Vas patency determined 2 months after vasovasostomy was 80% (8 of 10) in the mature group and 89% (8 of 9) in the immature group. No animal that had contralateral testicular changes after vasectomy and a patent vas after vasovasostomy showed improvement in testicular histology. Conclusion(s): It appears that contralateral testicular damage associated with unilateral vasectomy is not improved 2 months after successful vasovasostomy in mature or immature Lewis rats.