unilateral obstruction or injury to the vas deferens can result in significant injury to the contralateral testicle ( 1 - 3 ) .
although studies have indicated that the damage can be reversed by repair of the obstructed vas deferens ( 4 ) , other studies have suggested that the effects are irreversible ( 2 ) .
although various pathways have been proposed , the mechanism of contralateral testicular deterioration remains controversial .
the most popular theory , commonly proposed to explain the contralateral testicular damage , has been an autoimmune response ( 3 , 5 ) . currently , the probable mechanism of contralateral injury is accepted as a vasospasm through a sympathetic reflex arc , and hypoxia may be the reason for contralateral injury after unilateral testicular obstruction ( 6 , 7 ) .
succeeding studies have shown decreases in testicular oxygen content and adenylate energy charge , and an increase in biochemical indicators of tissue hypoxia ( 8 , 9 ) .
chemical sympathectomy reduced the increase in biochemical indicators of tissue hypoxia and preserved spermatogenetic function ( 10 - 12 ) .
these findings suggested that contralateral testicular damage resulted from a reflex vasospasm preceded by sympathetic activation .
thus , 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 .
the experimental protocol was approved by the animal ethics committee of akdeniz university , turkey .
the rats were maintained under standard laboratory conditions with a 12 : 12 hr light : dark cycle , with free access to food pellets and tap water .
they were separated equally into the four groups : group 1 : a sham ( control ) group that received a placebo ; group 2 : a group with sham that received 6-hydroxydopamine hydrobromide ; group 3 : a group with unilateral left vasectomy that received a placebo ; group 4 : a group with unilateral left vasectomy that received 6-hydroxydopamine hydrobromide . within 24 hr of birth , 20 rats each received an intraperitoneal injection with placebo ( physiological saline solution 0.2 ml / day , for 7 days ) or 6-hydroxydopamine hydrobromide solution 0.075 mg / g , for 7 days .
dopamine solutions were prepared each day by dilution in physiological saline containing 0.1 mg / ml of ascorbic acid .
when 60 days old , each group of 20 rats was divided into two groups that underwent either a control operation or an operation to create unilateral left vasectomy . to create a unilateral abdominal testis ,
a left inguinoscrotal incision was made in the abdomen , and the left vas deferens was retrieved and exposed . using 4.0 silk suture ,
the incision was closed in 2 layers with 4.0 silk suture , in a running fashion .
briefly , the incision was made , vasa deferentia were exposed , 4.0 silk was passed , but the vasa deferentia were not ligated or transected .
eight weeks after surgery , each male rat was housed with two known fertile female rats for 25 days , and then their testes were harvested .
sections were cut and stained with hematoxylin - eosin , periodic acid - schiff ( pas ) and masson 's trichrome .
the 50 most circular tubules were identified in each testicular biopsy section and their diameters were measured using a 40 objective and an ocular micrometer .
the testicles were evaluated histologically with respect to the following characteristics : 1 ) seminiferous tubular diameter ; 2 ) morphology and progression of maturation of the germinal epithelium ; and
3 ) morphology of the tunica propria and interstitial components , specifically to determine whether fibrosis , hyalinization , or an inflammatory infiltrate could be identified .
germinal epithelial maturity was graded using a modified johnsen testicular biopsy score ( 13 ) ; using a 40 objective , 50 tubules were evaluated and each tubule was given a score from 1 to 10 .
the female rats were observed for an additional 25 days . the number of rats impregnated by each male rat and the number of rats delivered by each female rat were recorded .
the statistical comparisons between mstd and mtbs values of the groups were performed using multi - way analysis of variance .
total fertility rates of the groups were compared using t - test , with p<0.05 taken to indicate significant differences ; all values are presented as the mean ( sd ) .
a total of 6 rats died during study ( 1 from group 1 , 1 from group 2 , 1 from group 3 , and 3 from group 4 ) .
there was no statistically significant difference in histological examination between any of the groups ( p>0.05 ) .
the mtbs of the ipsilateral and contralateral testes were 9.670.50 and 9.780.44 in group 1 , 8.670.5 and 9.780.42 in group 2 , 6.220.44 and 7.110.33 in group 3 , and 7.220.43 and 8.290.48 in group 4 , respectively ( p>0.05 ; fig .
1 ) . while the mstd of the ipsilateral and contralateral testes did not differ significantly between groups , those of the ipsilateral testes of all of the groups were lower than in the corresponding contralateral testes .
the mstd of the ipsilateral and contralateral testes were 242.66689.326 and 249.90675.907 in group 1 , 178.01338.392 and 209.673104.931 in group 2 , 147.1136.667 and 155.89312.954 in group 3 , and 165.44015.449 and 188.14023.360 in group 4 , respectively ( p>0.05 ; fig .
these rates were 88.8% in group 1 , 66.6% in group 2 , 77.7% in group 3 , and 85.7% in group 4 .
total fertility rate of group 4 was significantly higher than that in group 3 ( p<0.05 ) .
unilateral obstruction of the vas deferens can occur for a variety of reasons , including epididymitis , trauma , or iatrogenic damage to the vas during hydrocele repair , orchidopexy , or inguinal herniorrhaphy ( 14 ) .
unilateral injury to the vas deferens has been associated with damage to the contralateral testicle , and this damage is thought to be mediated through antisperm autoantibodies ( 3 , 5 ) .
a current theory of contralateral testicular injury proposes a reflexive decrease in contralateral testicular blood flow and an increase in the biochemical indicators of tissue hypoxia within the contralateral testes ( 6 , 7 ) .
the mechanism by which contralateral testicular blood flow is affected after unilateral vas deferens obstruction has not been thoroughly evaluated .
the vasospasm in the contralateral testis was suggested to arise by a neurovascular pathway triggered by an ipsilateral testicular stimulus , running through a sympathetic reflex arc , resulting in decreased blood flow ( 15 ) .
ipsilateral vas deferens obstruction also resulted in increased levels of lactic acid and hypoxanthine in both testes .
decreases in the blood flow of both testes and oxidative stress have been reported after ipsilateral efferent duct ligation ( 16 ) .
ligation of the vas deferens should increase the pressure within the distal structures and the structure of the tunica albuginea may not allow for expansion to decrease the pressure
. the increased pressure may therefore decrease the blood flow to the ipsilateral testis through increasing the intratesticular pressure .
the increases in the levels of lactic acid and hypoxanthine within the contralateral testis suggest a reflex decrease in contralateral testicular blood flow when the ipsilateral testis is under stress after ligation of the ipsilateral vas deferens .
andiran et al . ( 1 ) reported that unilateral testicular torsion , unilateral vas deferens obstruction , unilateral abdominal testis , and unilateral venous obstruction not only damage the ipsilateral but also the contralateral testes . as the lactic acid and hypoxanthine levels within the contralateral testis were greater than in the controls ,
testicular torsion and vas deferens obstruction seem to share a common pathway , which may be a reflex decrease in contralateral testicular blood flow , for their effects on the contralateral testis ( 1 ) .
an effective circulatory system in the testis is the most critical factor for functional spermatogenesis ( 17 ) .
the increase in biochemical indicators of tissue hypoxia and contralateral testicular damage can be prevented by chemical sympathectomy ( 10 , 11 , 18 ) .
experimentally , the sympathetic nervous system was also activated by partial ligation of the left renal vein in the adult rat , which was blocked by chemical sympathectomy ( 19 ) .
the evaluation of contralateral testis through the model of testicular torsion has revealed a decrease in blood flow and an increase in factors associated with tissue hypoxia , e.g. , lactic acid and hypoxanthine ; chemical sympathectomy reduced the effects of tissue hypoxia and preserved testicular histology , fertility and fecundity ( 9 , 10 ) . additionally , unilateral
undescent has also been reported to result in elevated levels of the products of tissue hypoxia in the contralateral testis ( 20 ) .
( 18 ) evaluated the effects of abdominal testis on ipsilateral and contralateral testicular histology , fertility and fecundity in rats that were chemically sympathectomized neonatally . in their investigation , although fertility and fecundity rates and mtbss were not significantly different , chemical sympathectomy prevented the decrease in mstds that occurred in the contralateral testis .
these findings suggested that the sympathetic system may play a role in contralateral testicular deterioration .
therefore , we evaluated the effects of unilateral vasectomy on ipsilateral and contralateral testicular histology and fertility in rats that were chemically sympathectomized neonatally . 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 the sympathetic nervous system may play a role in the testicular degeneration associated with 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 . 
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION