Yonago Acta medica 2000;43:1–9

Bilateral Testicular Consequences in the Unilateral Vasectomy of
Immature Rats
Tetsuhiro Ikeda and Nikolaos Sofikitis
Department of Urology, Faculty of Medicine, Tottori University, Yonago 683-0826, JapanWe evaluated the effects of unilateral obstruction of the vas deferens on testicular
endocrine and exocrine function in rats. The left vas deferens was ligated and divided
in 1-week-old Wistar rats. Additional rats of the same age underwent a sham operation.
Bilateral testicular weight and epididymal weight were compared between the vasectomized and sham-operated animals at 4, 8 and 12 weeks postoperation. Intratesticularversus intraabdominal temperature difference, epididymal caudal sperm content(ECSC), motility (ECSM) and in vitro fertilizing capacity (IVF) were compared between
the vasectomized and sham-operated animals at 12 weeks postoperation. Serumtestosterone response to human chorionic gonadotropin and bilateral testicular weight
were significantly smaller in the vasectomized animals than in the sham-operated animals
at 8 and 12 weeks postoperation. Bilateral ECSC, ECSM and IVF outcomes were significantly smaller in vasectomized rats than in sham-treated rats 12 weeks postoperatively.
Bilateral intratesticular versus intraabdominal temperature differences were not significantly different between the vasectomized and control rats at 12 weeks postoperation.
Unilateral obstruction of the vas deferens results in a bilateral defect in spermatogenesis
and in the epididymal sperm maturation process.
Key words: epididymis; spermatogenesis; testicular function; unilateral vasectomy

the epididymis. Spermatozoa received from thecaput epididymis show weak tail movement.
However, more than half of the spermatozoa
taken from the cauda epididymis show mature
motility patterns (low-amplitude and highfrequency beats) (Bedford et al., 1973). Morphological changes have been observed also in
epididymal spermatozoa. Along the epididymal duct, light and scanning electron microscopy reveal that the shape of the sperm cytoskeleton changes and that the cytoplasmic
droplet regresses and moves toward the posterior end of the middle piece (Flechon and Hafez
1975). Antypas et al. (1994) demonstrated
bilateral epididymal dysfunction following
ipsilateral vas deference obstruction.
The vas deferens is a tubular structure thatcarries sperm from the cauda epididymis to the
ejaculatory duct. In a cross section view, it canbe seen that the vas deferens consists of 3 mus-The epididymis is a complex system whosefunctions include sperm transit and storage, thematuration of spermatozoa, and the creation of
sperm fertilizing potential. The basic mechanism for moving spermatozoa through theepididymis involves spontaneous contractionsof the epididymal ducts (Schlegel and Chan,
1998). Sperm epididymal transit time is influenced more by daily testicular sperm production than by age (Johnson and Varner, 1988). In
humans, almost half of the total number of
epididymal spermatozoa is stored in the caudal
region. Although the cauda epididymis plays animportant role in sperm storage, long term
storage of spermatozoa in the caudal region
results in the aging of spermatozoa and impaired motility (Yeung et al., 1993) and lower
capacity for fertilization (Zeuzus et al., 1992).
Human spermatozoa develop an increased
capacity for motility as they migrate throughAbbreviations: BWW, Biggers-Whitten-Whittingham; ECSC, epididymal caudal sperm content; ECSM,
epididymal caudal sperm motility; IVF, in vitro fertilizing capacity; hCG, human chorionic gonadotropin

1

T. Ikeda and N. Sofikitis

cular layers and a mucosal inner layer (Neaves,1975). Adrenergic nerve fibers are also seen inall 3 layers, with the greatest concentration in
the outer layer (McConnel et al., 1982). During
sexual rest, epididymal contents are transported
into the urethra gradually by spontaneous
motility. Once sexual stimulation and ejaculation occur, the contents of the vas deferens arepropelled into the urethra by strong contractions
that are elicited by adrenergic neurotransmitters(Bruschini et al., 1977). It is also known thatthe vas deferens secretes glycoproteins into thetubular lumen (Nistal et al., 1992) and absorbs
proteins and spermatozoa from the tubular lumen (Murakami and Yokoyama, 1989). Theseabsorptive and secretory functions of the vas
deferens may contribute to the generation of aluminal environment capable of supporting
the maturation of sperm fertilizing ability(Bedford, 1994).
Damage of the vas deferens during childhood often occurs as a complication of inguinal
surgical operations such as inguinal herniorrhaphy. Matsuda et al. (1992) reported that theincidence of vasal obstruction in infertile menwith histories of herniorrhaphy was as high as
27.8% when unilateral obstruction was diagnosed. More than half the patients with vasal
obstruction caused by infant inguinal herniorrhaphy have serum antisperm antibodies(Matsuda et al., 1993) and oligozoospermia(Parkhouse and Hendry 1991). Several experiments have been reported regarding the influence of vas deferens obstruction on spermatogenesis and the sperm maturation process.
Increased diameters of seminiferous tubules
have been observed in the testes of animals withvas deference obstruction (Lamano-Carvalho etal., 1984). Additionally, interstitial sperm
granuloma surrounding epididymal tubules has
been revealed histologically in humans postvasectomy (Silber, 1979). Vasectomy may
result in increased pressure within the ipsilateral epididymal tubule leading to the development of granuloma around the tubule. Furthermore, a significant reduction of Sertoli cells
and spermatid per tubular cross section andfocal interstitial fibrosis have been observed in
the human testis postvasectomy (Jarow et al.,1985). However, the effect of unilateral obstruction on contralateral testicular function has
not been adequately studied. Antypas et al.
(1994) showed that a bilateral deficiency inboth Leydig and Sertoli cell secretory functions
occurs in unilaterally vasectomized animals
with an overall result of bilaterally impaired
spermatogenesis and inhibited sperm maturation process. Furthermore, whether unilateralvasectomy affects bilateral sperm fertilizing
capacity is unknown. The present study focuseson the effect of left vasectomy on bilateral testicular and epididymal function and on overall
sperm fertilizing capacity.

Materials and Methods

Animals
Five female and 5 male 12-week-old Wistar rats
were obtained from Shimizu Experimental
Material Company (Kyoto, Japan). Following
mating experiments, male pups received either
a left vasectomy or a sham operation at the ageof 7 days. Vasectomized animals were divided
into Groups A (n = 11), B (n = 11) and C (n =11). Sham-operated animals were divided into
Groups A1 (n = 11), B1 (n = 11) and C1 (n =11). Groups A and A1 were sacrificed at 4
weeks postoperation. Groups B and B1 were
killed at 8 weeks postoperation, and Groups C
and C1 were killed at 12 weeks postoperation.

Surgical procedure
Pups were anesthetized for surgery by inhalation of diethyl ether. A small vertical midline
lower abdominal incision was made. The left
vas deferens was ligated twice with absorbablesutures and then transected between theligatures. The spermatic vessels were carefully
dissected. The wound was closed in 2 layers; 4zero absorbable sutures were used for themusculature and 4-zero absorbable sutures forthe skin. Sham operations were performed in
the same manner except that the vas deferens
was neither ligated nor divided.
At the end of the experimental period, bi2

Bilateral testicular consequences of unilateral vasectomy

ments: the head, the body and the tail. The
epididymal tail was trimmed and minced in 5
mL of Biggers–Whitten–Whittingham (BWW)
medium (Sofikitis et al., 1992) adjusted to pH
7.4 at 37˚C with 6 mol/L of sodium hydroxide.
The minced epididymal tissue was then separated from the liberated spermatozoa by filtration through a stainless steel wire mesh with apore size of 60 µm. Six droplets of the filtrate
were used for assessing the sperm count (number of spermatozoa/mL BWW medium) and theaverage number was calculated for each animal.
The sperm count was determined using a
Makler Counting Chamber (Sefi Medical
Instruments, Haifa, Israel). The chamber wasplaced on the slide of an ordinary microscope,and 20-power objective and 10-power eyepieces were used. Ten droplets of filtrate werecounted to calculate the percentage of motile
spermatozoa immediately after its preparation,
so that the motility estimate became moreaccurate.

lateral intratesticular versus intraabdominal
temperature differences were evaluated inGroups C and C1 under sodium pentobarbital
anesthesia (25 mg/kg; Nembutal, Abott Laboratories, Chicago, IL). One milliliter of blood
was aspirated from the left renal vein of all
animals in Groups B, B1, C and C1. Thenhuman chorionic gonadotropin (hCG) (1500
units; Teikoku Zoki Co., Tokyo, Japan) was
administered intramuscularly and 3 h later, 1
mL of blood was received from the right renal
vein. Blood samples were processed for testosterone serum evaluation. Subsequently, testicular weight and epididymal weight were assessed bilaterally. Then each epididymis was
divided into a head, body and tail. Epididymal
caudal sperm content (ECSC), epididymal caudal sperm motility (ECSM) and in vitro fertilizing capacity (IVF outcome) were evaluatedin Groups C and C1.

Testicular temperature
Intraabdominal and bilateral testicular temperature were assessed by percutaneous insertion of
a 29-gauge needle probe attached to a digital
thermometer (Unique Medical, PTC201 model,
Tokyo) in Groups C and C1. Intraabdominal
temperature was monitored using a rectal probe
and body temperature was maintained between
36.6 and 37.4˚C. The difference between theintraabdominal and intratesticular temperature(∆T) was recorded (Sofikitis et al., 1992).

Determination of serum testosterone
concentration
Serum testosterone concentration was determined by radioimmunoassay using a kit fromthe Nihon DPC Corporation (Tokyo) according
to the method of Coyotupa et al. (1972). The
intra- and inter-assay coefficients of variation
were 5.5 and 9.2%, respectively. The sensitivity of the assay was 0.1 ng/mL.

Testicular and epididymal weight

Preparation of sperm suspension for IVF

In all groups, each testis and epididymis were
excised, dissected free of surrounding tissue,
and weighed on a Mettler Basbal Scale (Delta
Range, Tokyo).

Epididymal caudal suspensions were centrifuged at 300 × g for 20 min. Sperm pellets weretransferred to Toyoda and Chang medium(Toyoda and Chang, 1974). Finally, sperm
suspensions containing 2 × 106 spermatozoa/
mL were prepared and processed for IVF aspreviously described (Toyoda and Chang,1974).

Epididymal caudal sperm content andquantitative sperm motility
Each epididymis was separated carefully fromthe respective testicle under 10 × magnification
provided by a stereo zoom microscope (Model
TL2, Olympus Corp., Tokyo) in Groups C andC1. The epididymis was divided into 3 seg-

Collection of oocytes and IVF
Immature female rats were injected subcutaneously with 25-IU pregnant mare serum3

T. Ikeda and N. Sofikitis

Table. 1. Difference between intraabdominal and intratesticular temperature
C: vasectomy group [11]
Left
Right

C1: sham group [11]
Left
Right

∆T (˚C)4.2 ± 0.5
4.5 ± 0.7
4.3 ± 0.7
Values are expressed as mean ± SD.
[ ], number of animals.
∆T, ∆temperature: intraabdominal versus intratesticular temperature difference.
There were no significant differences in ∆T value within each group or between groups.

gonadotropin (Sigma Chemical Co., St. Louis,
MO). Fifty-four hours later the rats were
injected intraabdominally with 20-IU hCG(Teikoku Zoki Co., Tokyo). The rats were
killed 19 h after hCG injection. The oviducts
were removed and each ampullar portion wasplaced into a plastic dish containing the Toyoda
and Chang medium (Toyoda and Chang, 1974).
The oocytes in cumulus masses were removed
from the oviducts and introduced into the
Toyoda and Chang medium. A volume of 0.1
mL of sperm suspension was introduced into
0.9 mL of the Toyoda and Chang medium containing the oocytes within cumulus masses.
The dishes were kept within a CO2 incubator(5% CO2 in air). Ten oocytes were inseminatedwith spermatozoa from each caudal epididymis
of each rat in Groups C and C1.

4.7 ± 0.6

Examination of oocytes
Twenty-four hours after insemination, the percentage of oocytes with 2 pronuclei plus a 2ndpolar body was determined microscopically(Olympus IX-70, Tokyo).

Statistical analysis
Intergroup differences were analyzed using theunpaired t-test. A P value less than 0.05 wasconsidered statistically significant. Values
were expressed as mean ± SD.

Results

Testicular temperature
No significant differences were observed inmean DT values between the vasectomized rats

Table 2. Testicular weight and epididymal weight
WeightVasectomy group [11]WeightSham group [11]

(mg)

Left

Right

(mg)

Left

Right

TesticularA
B
C

440 ± 481156 ± 89*
1228 ± 79*

484 ± 711280 ± 80***
1367 ± 88***

Testicular
A1
B1
C1

490 ± 62
1465 ± 98**
1741 ± 76**508 ± 51
1518 ± 90****1763 ± 93****

EpididymalAB

79 ± 30151 ± 44*74 ± 28302 ± 57***

Epididymal
A1
B1

83 ± 21371 ± 68**

77 ± 45383 ± 63****C

386 ± 50*429 ± 54***C1

487 ± 50**521 ± 39****

Data are expressed as mean ± SD.
[ ], number of animals.
Within each transverse line, * versus **; *** versus ****; * versus ***: P < 0.05.
Values of testicular weight and epididymal weight were significantly larger bilaterally in Groups B1 and C1
than in Groups B and C respectively.
Values of testicular weight and epididymal weight of the left side were significantly smaller than those of theright side in Groups B and C.

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Bilateral testicular consequences of unilateral vasectomy

Table 3. Sperm content and motility in the cauda epididymis
C: vasectomy group [11]
Left

Right

C1: sham group [11]
Left

Right

ESCS

(× 10 /mL)47.2 ± 9.4*

61.5 ± 7.6***

77.0 ± 6.6**

75.8 ± 8.7****

ECSM

(%)

19.1 ± 7.6*

46.8 ± 5.7***

60.0 ± 7.0**

65.6 ± 5.0****6

Data are expressed as mean ± SD.
[ ], number of animals.
ECSC, epididymal caudal sperm content; ECSM, epididymal caudal sperm motility.
Within each transverse line, * versus **; *** versus ****; * versus ***: P < 0.05.
Values of ECSC and ECSM were significantly larger in Group C1 than in Group C.
Values of ECSC and ECSM of the left side were significantly smaller than these of the right side in Group C.

and sham-operated rats at 12 weeks postoperation (Table 1).

Caudal epididymal sperm count andmotility
ECSC was significantly lower bilaterally in theunilaterally vasectomized rats than in the respective control group at 12 weeks postoperation (Table 3). ECSM was also significantly
lower bilaterally in the unilateral vasectomized
rats than in the respective control animals.
ECSC and ECSM values of the left side weresignificantly smaller than those of the right sidein the vasectomized rats at 12 week postoperation (Table 3).

Testicular and epididymal weight
No significant difference was observed in bilateral testicular and epididymal weight between unilaterally vasectomized rats and shamtreated rats at 4 weeks postoperation. However,
the weight of each left and right testis and epididymis was significantly lower in the vasectomized rats than in the sham-treated rats at 8
and 12 weeks postoperation. The weights of theleft testis and epididymis were significantly
smaller than those of the right side in vasectomized rats at 8 and 12 weeks postoperation(Table 2).

Leydig cell function
Serum basal testosterone levels showed nosignificant difference between the unilaterally
vasectomized rats and sham-treated rats at 8

Table 4. Testosterone responses to hCG stimulation
Level (ng/dL)

Vasectomy group [11]Level (ng/dL)

Sham group [11]Basal testosterone
BC

155.3 ± 22.6
159.1 ± 31.5

Basal testosterone
B1
C1

146.8 ± 32.4
189.9 ± 76.8

Testosterone response
Testosterone response
B
562.1 ± 82.2*
B1
817.8 ± 140.2**
C729.8 ± 123.9*
C11055.7 ± 162.0**
Data are expressed as mean ± SD.
[ ], number of animals.
Within each transverse line, * versus **: P < 0.05.
There were no significant difference in basal testosterone level between Groups B and B1, and between
Groups C and C1.
Values of testosterone responses were significantly larger in Group B1 than in Group B, and in Group C1 thanin Group C.

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T. Ikeda and N. Sofikitis

Table 5. Outcome of in vitro fertilization using cauda epididymal spermatozoa
Number of

C: vasectomy group [11]oocytes

Left

Right

C1: sham group [11]
Left

Right

Inseminated oocytes
110
110
110
110
2-PN oocytes†
34 (31)*54 (49)***79 (72)**84 (76)****[ ], number of animals; ( ), percentage.
† Oocytes with 2 pronuclei plus a 2nd polar body.
Within each transverse line, * versus **; *** versus ****: P < 0.05
Percent of fertilized oocytes was significantly larger bilaterally in Group C1 than in Group C.
Percent of fertilized oocytes of the left side was significantly smaller than that of the right side in Group C.

herniorrhaphy compared to vasectomy with anaverage obstruction period of 8 years (Matsuda
et al., 1996).
All of the above studies examined theeffects of unilateral vas deferens damage on theipsilateral testis. We attempted to evaluate theeffects of unilateral vasectomy on bilateral
testicular and epididymal functions. The resultsof the current study support the finding that unilateral vasectomy results in bilateral damage inspermatogenesis. This is indicated by the significantly smaller ECSC in unilaterally vasectomized rats than in control rats bilaterally. In
addition, the significantly smaller ECSM inunilaterally vasectomized rats than in control
rats bilaterally indicates a deficiency in the epididymal sperm maturation process bilaterally invasectomized rats. The epididymal sperm maturation process is known to involve a cascade ofbiophysical and biochemical events that resultin progressive sperm motility, the ability forcapacitation, and the acquisition of fertilizing
potential. Therefore, the significantly smaller
bilateral IVF outcome in unilaterally vasectomized rats may be attributed to defects in theepididymal sperm maturation process and subsequently reduced sperm fertilizing capacity.
Defects in the epididymal sperm maturation
process leading to an impaired progressive
sperm motility, the ability to undergo capacitation and to penetrate the zona pellucida of oocytes results in a diminished sperm fertilizing
capacity and suboptimal IVF outcome. Defects
in bilateral epididymal and testicular function
are also supported by the findings of a significantly smaller epididymal and testicular weightand 12 weeks postoperation (Table 4). However, peripheral serum testosterone responses tohCG stimulation were significantly lower in theunilaterally vasectomized rats than in the control animals at 8 and 12 weeks postoperation(Table 4).

Fertility potential in vitro
The percentage of oocytes with 2 pronuclei plus
a 2nd polar body after undergoing the IVF
technique using caudal spermatozoa was significantly lower bilaterally in the unilaterally
vasectomized animals than in the control rats.
The percent of fertilized oocytes of the left side
was significantly smaller than that of the rightside in the vasectomized rats at 12 weeks postoperation (Table 5).

Discussion
Inguinal canal reconstruction operations suchas varicocelectomy and orchiopexy procedures
entail the risk of damaging the ipsilateral vas
deferens. Several experimental and clinicalstudies have demonstrated an adverse effect ofvas deferens injury on ipsilateral testicularfunction. Matsuda et al. (1992) reported thatthe incidence of unilateral vas deferens obstruction caused by inguinal herniorrhaphy was
26.7% for infertile patients with a history of theoperation. They also reported that there werefewer total germ cells and a larger seminiferous
tubular diameter in patients with lifelong vasal
obstruction caused by childhood inguinal
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Bilateral testicular consequences of unilateral vasectomy

in vasectomized rats. It is known that strong
positive correlations exist significantly between
epididymal weight and epididymal function,and between testicular weight and testicularfunction (Takihara et al., 1987).
Although we did not evaluate Leydig andSertoli cell function separately on the left andright side, the significantly smaller serum testosterone responses in the vasectomized ratssuggests a defect in Leydig cell function in
vasectomized animals. A deficiency in Leydig
cell secretory function may be responsible forthe defects in spermatogenesis and the epididymal sperm maturation process in vasectomized
rats because it is known that optimal concentrations of intratesticular testosterone andepididymal testosterone are necessary for the
maintenance and activation of spermatogenesis
and the epididymal sperm maturation process(Sofikitis et al., 1992).
The defect in ipsilateral testicular function
and spermatogenesis in animals with an obstructed left vas deferens can be easily explained. Increased diameters of ipsilateral seminiferous tubules have been observed in thetestes of animals with obstructed vas deferens(Lamano et al., 1984). Furthermore, interstitialsperm granuloma surrounding epididymal tubule postvasectomy has been revealed histologically (Silber, 1979; Matsuda et al., 1992) inhumans. Also, a significant reduction of Sertoli
cells and spermatid count per tubular crosssection and focal interstitial fibrosis have also
been observed in the human testis postvasectomy (Matsuda et al., 1996). We suggest thathigh pressure within the epididymal and seminiferous tubules due to vas obstruction leads toextension and dilation of the tubules and theexit of spermatozoa from epididymal and seminiferous tubules which may result in interstitial
fibrosis of the testes and secondary epididymal
obstruction. In addition, accumulation of toxic
substances from disintegrated spermatozoa may
occur within the testis and epididymis anddetrimentally affect spermatogenesis and theepididymal sperm maturation process. Furthermore, the increased pressure within the testicular seminiferous tubules may detrimentallyaffect ipsilateral Leydig cell function either
directly (due to mechanical pressure from the
expanded seminiferous tubules) or indirectly(due to Sertoli cell secretory dysfunction). It is
known that the Sertoli cells affect Leydig cellfunction via the production of peptides(Sylvester, 1996).
However, it is not easy to explain the defects
in contralateral testicular function, spermatogenesis, the epididymal sperm maturation
process, and sperm fertilization potential after
obstruction of the unilateral vas deferens.
Sperm antibodies are found in the serum of
approximately 80% of bilaterally vasectomized
men and achievement of pregnancy after vasectomy reversal is significantly less when postoperative antisperm antibody titer is high(Parslow et al., 1982). Parkhouse and Hendry(1991) reported that of 17 infertile patients withunilateral vas obstruction following inguinal
surgery in childhood, 11 developed oligospermia and all had detectable titers of antisperm antibodies. We speculate that thedamage in the unilateral testis blood barrier
leads to an autoimmune disorder that results intesticular dysfunction and subsequent damage
to the epididymal maturation process in theright side. In addition, antibodies after left
vasectomy may not develop only against spermatozoa but also against the components ofseminiferous tubules and interstitial testicular
tissue in the left side. Left Leydig cells may bedamaged due to pressure from the dilated,overexpanded seminiferous tubules. This isconsistent with the smaller left testicular weightin left vasectomized rats. Antibodies or substances toxic to components of seminiferous
tubules and interstitial testicular tissue (Leydigcell) of the diseased left testis may affect righttesticular seminiferous tubule components(spermatozoa or Sertoli cells) or Leydig cells
and subsequently may influence right side spermatogenesis, the epididymal sperm maturation
process and epididymal caudal sperm fertilizing
capacity. The latter thesis is also consistent
with a previous study by Antypas et al. (1994)
who demonstrated bilateral testicular damage
and impaired epididymal sperm maturation

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T. Ikeda and N. Sofikitis

3 Bedford JM, Calvin HI, Cooper GW. The maturation of spermatozoa in the human epididymis. J
Reprod Fertil Suppl 1973;18:199–213.
4 Bruschini H, Schmidt RA, Tanagho EA. Studies
on the neurophysiology of the vas deferens.
Invest Urol 1977;15:112–116.
5 Coyotupa J, Parlow AF, Abraham GE. Simultaneous radioimmunoassay of plasma testosterone and dihydrotestosterone. Anal Lett 1972;
5:329–340.
6 Flechon JE, Hafez ES. Spermiation and epididymal maturation of spermatozoa in the bonnet
macaque (Macaca radiata) as viewed by scanning electron microscopy. Fertil Steril 1975;26:
1219–27.
7 Jarow JP, Budin RE, Dym M, Zirkin BR, Noren
S, Marshall FF. Quantitative pathologic changes
in the human testis after vasectomy. N Engl J
Med 1985;313:1252–6.
8 Johnson L, Varner DD. Effect of daily spermatozoon production but not age on transit time of
spermatozoa through the human epididymis.
Biol Reprod 1988;39:812–817
9 Lamano-Carvalho TL, Favaretto AL, AntunesRodrigues J. Histophysiological study of vasectomized rats. Braz J Med Biol Res 1984;17:83–
91
10 McConnell J, Benson GS, Wood JG. Autonomic
innervation of the urogenital system: adrenergic
and cholinergic elements. Brain Res Bull 1982;
9:679–694.
11 Matsuda T, Horii Y, Yoshida O. Unilateral obstruction of the vas deferens caused by childhood
inguinal herniorrhaphy in male infertility patients. Fertil Steril 1992;58:609–613.
12 Matsuda T, Ogura K, Muguruma K, Yoshida O,
Horii Y. Serum antisperm antibodies in men withvas deferens obstruction caused by childhood
inguinal herniorrhaphy. Fertil Steril 1993;59:1095–1097.
13 Matsuda T, Hiura Y, Muguruma K, Okuno H,
Horii Y, Yoshida O. Quantitative analysis of testicular histology in patients with vas deferens
obstruction caused by childhood inguinal
herniorrhaphy: comparison to vasectomized
men. J Urol 1996;155:564–567.
14 Murakami M, Yokoyama R. SEM observationsof the male reproductive tract with special reference to epithelial phagocytosis. Prog Clin Biol
Res 1989;296:207–214.
15 Neaves WB. Biological aspects of vasectomy.
In: Greep RO, Astwood EB, eds. Handbook ofphysiology. Section 7. Male reproductive system. Baltimore: Williams and Wilkins; 1975. p.
383–404.
16 Nistal M, Santamaria L, Paniagua R. The
ampulla of ductus deferens in man. Morphological and ultrastructural aspects. J Anat 1992;
180:97–104.

process in unilaterally vasectomized animals.
More studies are required to explain thesemechanisms.
It appears that bilateral epididymal caudal
sperm fertilizing capacity decreases after unilateral vasectomy at an early age. Therefore, inthe case of iatrogenic injury of the vas deferens
during childhood, spermatozoa may not beallowed an optimal fertilizing capacity. Subsequently, assisted reproductive techniques ininfertile adolescents with a history of unilateralvas deferens damage may not be successful.
The latter men require anastomosis of the injured vas deferens which will definitely increase
the sperm count in the ejaculate and may improve testicular function. Therefore, assisted
reproductive techniques may not be the first
choice for the therapeutic management of men
with vas deferens obstruction.
The absence of significant differences intesticular versus intraabdominal temperature
difference may suggest that the increased intratesticular pressure postvasectomy is not accompanied by a defect in the efficiency of the ipsilateral counter-current heat exchange systemthat regulates the testicular temperature. The
absence of significant differences in testicularweight between vasectomized and control rats
at 4 weeks postoperation suggests that a lagtime is necessary for the development andmanifestation of the detrimental consequencesof unilateral vasectomy on bilateral testicularfunction.
In conclusion, we demonstrated that bilateral testicular and epididymal damage develops after unilateral vas deferens injury. We
advocate that unilateral vas deferens injury
during inguinal operation in childhood should
be diagnosed and repaired as early as possible.

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(Received December 9, Accepted December 25, 1999)

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