Yonago Acta medica 1999;42:41–49

Factors Inducing Vascularization Improve the Spermatogenic andSteroidogenic Function of the Varicocelized Testis
Tadahiro Isoyama and Nikolaos Sofikitis
Department of Urology, Faculty of Medicine, Tottori University, Yonago 683-0826, JapanWe evaluated whether alterations in testicular vascularization and fluid dynamics havea role in the development of testicular damage in varicocelized animals. Left varicocele
was induced in 6 groups of rats (A, B, C, D, E and F; 7 rats in each group). Four times
a week, rats of group A, B, C, D, E and F underwent intrascrotal injections of saline,
insulin-like growth factor-I, fibroblast growth factor, tumor necrosis factor-α, vascularendothelial growth factor or all the previous factors together, respectively. Additionally
7 rats were sham-operated (group G). At 8 weeks post-operation, groups E, F and G
showed significantly higher left epididymal sperm content and motility, testosterone
responses to human chorionic gonadotropin stimulation and intraabdominal versus
intratesticular temperature differences than group A. Histological sections showedthat the number of vessels per seminiferous tubule was significantly larger in groups E
and F than in group A. Factors inducing vascularization have a beneficial effect on thefunction of the varicocelized testis attributable to improvement of testicular tissue
nutrition or to amelioration of the functionality of the countercurrent heat exchangesystem.
Key Words: growth factors; testis; spermatozoa; varicocele

ejaculation prior to the introduction of theassisted reproduction techniques offers the possibility of natural conception, has a lower costthan assisted reproduction, provides an opportunity for a second child, obviates the need forovarian stimulation known to include risks forthe female partner, and finally increases theprobabilities for a positive outcome of assisted
reproduction technology that may be applied if
natural conception has not been achieved bypost-medical or surgical treatment. Therefore,
IVF, intracytoplasmic sperm injection and ooplasmic injections of round spermatid nuclei or
secondary spermatocytes should be applied
only after having attempted to improve testicular function and semen quality with the mostcontemporary surgical or medical (conservative) treatments.

In most Western and a few Eastern countries
male infertility is both a private and social problem. Although several assisted reproduction
techniques provide an attractive mode of management for oligospermia (in vitro fertilization[IVF] trials), severe oligospermia/asthenospermia (intracytoplasmic sperm injection
trials), azoospermia with testicular spermatozoa(intracytoplasmic sperm injection trials), oreven azoospermia without testicular spermatozoa (ooplasmic injections of round spermatid
nuclei or secondary spermatocytes) (Palermo
et al., 1992; Sofikitis et al., 1998a, 1998b), conservative and surgical therapy of male infertility should always be present in the physician’s
mind and should be applied prior to assisted
reproduction techniques for the improvement ofqualitative, quantitative and functional sperm
parameters. Improvement of the quality ofAbbreviations: FGF, fibroblast growth factor; hCG, human chorionic gonadotropin; IGF, insulin-like growth
factor; IVF, in vitro fertilization; L∆T, difference between intraabdominal and left intratesticular temperature;
PBS, phospate buffered saline; TC, Toyoda and Chang; TNF, tumor necrosis factor; VEGF, vascular endothelial growth factor; VIF, vascularization-inducing factor

41

T. Isoyama and N. Sofikitis

Varicocele is one main cause of male infertility (Sofikitis and Miyagawa, 1993). Varicocelectomy is an efficient procedure in improving semen characteristics in the majority of men
with varicocele (MacLeod, 1965). However, asignificant number of men with varicocele remain infertile post-varicocelectomy. For thelatter population of men with varicocele, additional surgical or conservative treatments arenecessary prior to the introduction of assisted
reproduction techniques. Ligation of the righttesticular vein or hormonal administration havebeen recommended for men with varicocele
who do not improve post-varicocelectomy(Mehan and Chahval, 1982; Ameler and Dubin,
1987; Sofikitis et al., 1992a, 1992b). However,a considerable number of subjects with varicocele remain infertile even after the introduction of several surgical and medical modes oftreatment.
In the current study we evaluated the role ofgrowth factors inducing vascularization in the
spermatogenic and steroidogenic function of
the varicocelized testis taking into consideration that testicular malnutrition has been implied as one of the mechanisms mediating the
detrimental effect of left varicocele on ipsilateral testicular function (Harrison et al., 1983,
1986; Sofikitis and Miyagawa, 1993). The rat
was used as an experimental animal because itis relatively inexpensive, it can be maintained
easily, anesthesia can be readily performed,
sperm and blood samples can be collected, andinduction of left varicocele in the rat is accompanied by most of the consequences known tooccur in the human varicocelized testis.

Materials and Methods

Treatment of animals
Left varicocele was introduced in 6 groups (A,B, C, D, E and F; 7 rats in each group) of 8week-old Sprague-Dawley rats during anesthesia with intraperitoneal pentobarbital sodium(25 mg/kg). Partial left renal vein ligation was
performed by the method of Sypol and coworkers (1981) at a point medial to the junction withthe adrenal and spermatic veins, so as to reduce
the renal vein to an external diameter of 1 mm.
Then all the anastomostic branches of the left
testicular vein were carefully ligated (Sofikitis
et al., 1992a, 1992b). Additionally, seven 8week-old rats were sham-operated (group G).
The latter rats underwent dissection of the left
testicular vein and the left renal vein medial tothe drainage of the adrenal and spermatic veins.
Four times a week, rats of groups A, B, C, D, E,
F or G underwent intrascrotal injections of saline, insulin-growth factor-I (IGF-I; 250 ng)(Sigma Chemical Co., St. Louis, MO), fibroblast growth factor (FGF; 25 ng) (Sigma Chemical Co.), tumor necrosis factor-α (TNF-α; 25ng) (Sigma Chemical Co.), vascular endothelial
growth factor (VEGF; 25 ng)(Sigma ChemicalCo.), all the previous factors (same doses)
together or saline, respectively (Table 1).
At 8 weeks post-operation, testicular andintraabdominal temperatures were measured.
Blood was aspirated from the right renal veinand processed for testosterone assay (basal
testosterone). Human chorionic gonadotropin(hCG, Teikoku Zouki Company, Tokyo, Japan)
was then injected (1,500 IU) intramuscularly.
Three hours later blood was aspirated from theright renal vein and processed for testosterone
assay (testosterone responses). At that time theleft testicular vein was checked for dilation.
Then, the left testis and left epididymal cauda
were carefully dissected. Left testicular weight
was measured and a piece of testicular tissue

Table 1. Surgical and medical treatments inthe various groups of rats
Group

Varicocele
induction

Medicaltreatment

A+
Saline
B
+
IGF-I
C
+
FGF
D
+
TNF-α
E
+
VEGF
F
+
All the above factors together
G–
Saline
FGF, fibroblast growth factor; IGF, insulin-likegrowth factor; TNF, tumor-necrosis factor; VEGF,
vascular endothelial growth factor.

42

Vascularization and testicular function

Left testicular and intraabdominal temperatures
were assessed by percutaneous insertion of a
29-gauge needle probe attached to a digital
thermometer (Unique Medical, Model PTC
201, Tokyo, Japan). Intraabdominal temperature was monitored with a rectal probe and bodytemperature was maintained between 36.7 and37.3˚C with radiant heat throughout the procedure. The difference between the intraabdominal and intratesticular temperature was recorded.

and Chang (TC) medium (Toyoda and Chang,1974) titrated to pH 7.4 at 37˚C with sodiumhydroxide. The minced epididymal tissue wasseparated from the liberated spermatozoa byfiltration through a stainless steel wire mesh,with a pore size of 60 µm. Ten droplets of thefiltrate were used for calculation of sperm countand motility. The average sperm count, quantitative motility and qualitative motility (motility
grade) were recorded. The sperm count wasdetermined with a Makler Counting Chamber(Sefi Medical Instruments, Haifa, Israel). The
chamber was placed on an ordinary microscopeslide, and a 20-power objective and 10-power
eyepiece were used for viewing. Quantitative
motility refers to the percentage of motile spermatozoa. Motility grade was evaluated using
an arbitrary grading system on a scale of 0 to 4,
with 0 representing no movement, 1 meaning
weak forward progression of some spermatozoa, 2 indicating steady forward progression ofmost motile spermatozoa, 3 meaning strong forward progression, and 4 representing very vigorous and rapid progression.

Determination of testicular weight

IVF trials

The left testis was excized, dissected free ofsurrounding tissue, and weighed on a Mettler
Basal Scale (Delta Range, Tokyo).

Sperm samples were centrifuged and resuspended in a volume of TC medium to produce
samples of sperm at a concentration of 2 × 106/mL. Sperm samples were incubated for 8 h at
37˚C under 5% carbone dioxide to allow for
sperm capacitation.
Oocytes were collected from immature rats
as previously described (Yamamoto et al.,1998). Cumulus masses containing 10 oocytes
were placed into drops of 0.9 mL of TC medium. The latter drops were mixed with 0.1 mLof the sperm suspensions. Thus, the sperm concentration was 200,000 spermatozoa/mL.
Oocytes were cultured at 37˚C for 24 h andwere then observed via an inverted microscope(IX-70, Olympus, Tokyo, Japan). The numberof oocytes with 2 pronuclei plus a second polar
body (fertilized oocytes) was recorded. IVF
outcomes are defined as ratio of fertilized
oocytes to inseminated oocytes.

was processed for immunohistochemistry using
a monoclonal antibody against endothelial
protein Factor VIII-related antigen to observeand count the testicular vessels. The number ofvessels per seminiferous tubule was recorded.
Spermatozoa were recovered from the left
epididymal cauda. Epididymal sperm content
and motility were appreciated. Thenepididymal caudal spermatozoa were processed
for IVF trials.

Determination of testicular temperature

Testosterone assay
Testosterone was determined by radioimmunoassay using kits from Nihon DPC Corporation(Tokyo) according to the method of Coyotupa
and coworkers (1972). The intra- and interassay coefficients of variation were 5% and 9%,
respectively. The sensitivity of the assay was
0.1 ng.

Epididymal caudal sperm content, quantitative and qualitative sperm motility
Each epididymis was separated carefully fromits testicle under a magnification of 10 provided
by a stereo zoom microscope (Model SZS,Olympus Corp., Tokyo). The epididymal tailwas recovered and minced in 5 mL of Toyoda
43

T. Isoyama and N. Sofikitis

Table 2. Effects of growth factors inducing vascularization on L∆T, left testicular weight,
basal testotsterone profiles and testoterone responses to hCG
Group

L∆T
(˚C)

Left testicular weight(mg)

Basal testosterone(ng/dL)

Testosterone response(ng/dL)A
2.5 ± 0.3803 ± 81163 ± 56619 ± 68B
2.8 ± 0.3**996 ± 92*,**148 ± 50803 ± 94*C
2.9 ± 0.4**1013 ± 101*,**152 ± 53782 ± 70*D
2.8 ± 0.3**1032 ± 108*,**181 ± 67878 ± 82*E
3.1 ± 0.3*,**1192 ± 94*,**204 ± 72851 ± 92*F
3.2 ± 0.3*,**1281 ± 99*,**210 ± 66854 ± 103*G
4.1 ± 0.4*
1433 ± 77*
201 ± 63864 ± 101*
hCG, human chorionic gonadotropin; L∆T, difference between intraabdominal and left intratesticulartemperature.
Within each column, * indicates a significant difference (P < 0.05) compared with varicocele group A,
whereas ** indicates a significant difference (P < 0.05) compared with control group G.

fasion. IVF outcome was analyzed using theχ2-test.

Immunohistochemistry
Testicular tissue was fixed with 20% formalinfor 48 h and embedded in paraffin. Using theserial section technique (7 µm section), antiFactor VIII stain was used for immunohistochemical analysis.
Endogenous peroxidase activity was quenched by incubation for 30 min with 3% H2O2, followed by washing in a phosphate buffered saline (PBS, pH 7.2). The sections were incubated with the antiserum for 18 h at 4˚C. PBS wasused to replace the antiserum in the controls.
Normal rabbit serum served as a blocking
agent. Rabbit anti-mouse IgG was used to detect bound antibodies. 3,3-Diaminobenzidine
tetrahydrochloride was used as the final chromogen. The sections were counterstained withhematoxylin.
Each section was viewed under a light microscope (× 200). The number of blood vessels per
seminiferous tubule was counted in the 5 different areas from each testis.

Results

Testicular temperature
The difference between intraabdominal and left
intratesticular temperature (L∆ T) was
significantly larger in groups E, F and G than ingroup A (Table 2).

Testicular weight
Left testicular weight was significantly larger ingroups B, C, D, E, F and G than in group A(Table 2).

Testosterone profiles
There were no significant differences in basal
serum testosterone profiles among all groups.
In contrast, serum testosterone responses tohCG stimulation were significantly larger ingroups B, C, D, E, F and G than in group A(Table 2).

Statistical analysis
Statistical analysis was performed using oneway analysis (P < 0.05) of variance followed by
Duncan’s multiple range tests (P < 0.05) toanalyze intergroup differences. All values wereexpressed as mean ± SD. A probability P <0.05 was considered to be statistically significant. All parameters were assayed in a blind

Epididymal caudal sperm qualitative,
quantitative and functional parameters
Left epididymal caudal sperm content, quantitative and qualitative motility were signifi44

Vascularization and testicular function

Table 3. Effects of factors inducing vascularization on epididymal caudal sperm content,
quantitative sperm motility, motility grade and IVF outcome
Group

Epididymal caudal
sperm content(× 106/mL)

Quantitative sperm
motility(% motile sperm)

Motilitygrade

IVF outcome(fertilized oocytes/
inseminated oocytes)

A
18 ± 824 ± 10
1.6 ± 0.2
19/70
B27 ± 10**36 ± 11**2.4 ± 0.8**44/70*,**
C
28 ± 10**33 ± 9**2.3 ± 0.6**
46/70*
D
30 ± 11*,**47 ± 11*,**2.7 ± 0.5*47/70*
E
53 ± 8*,**59 ± 11*2.9 ± 0.4*47/70*
F
62 ± 9*59 ± 13*3.2 ± 0.3*47/70*
G
68 ± 10*66 ± 10*
3.3 ± 0.4*53/70*
IVF, in vitro fertilization.
Within each column, * indicates a significant difference (P < 0.05) compared with varicocele group A,
whereas ** indicates a significant difference (P < 0.05) compared with control group G.

cantly smaller in group A than in groups D, E, F
and G. IVF outcome (ratio of fertilized oocytes/
inseminated oocytes) was significantly smallerin group A than in groups B, C, D, E, F and G(Table 3).

The number of vessels per seminiferous tubule
was significantly larger in groups E and F thanin groups A, B, C, D and G (Table 4).

Discussion

Blood circulation in the varicocelized testis

Left varicocele is one main cause of male infertility and is still an enigmatic disease, offering
an exciting and attractive field for research.
Thus, during the last 15 years several studies on

Figure 1 shows typical vessels in interstitial
testicular tissue (anti-Factor VIII stain, × 200).

Fig. 1. Immunohistochemical staining for Factor VIII antigen. Arrows indicate vessels in interstitial testicular tissue (× 200).

45

T. Isoyama and N. Sofikitis

Table 4. The number of vessels per seminiferous tubule

experimental varicocele models attempted toillustrate varicocele pathophysiology. However, several questions regarding this enigmatic
disease (Turner, 1983) still exist: Why is left
varicocele rare prior to the age of 8? Why does
obesity protect us from varicocele development?
Why do some men with varicocele remain fertile? How does varicocele affect testicularfunction? Several theories have been proposed
to explain the detrimental effect of left varicocele on bilateral testicular function: increase intesticular temperature (Saypol et al., 1981), increase in testicular hydrostatic pressure resulting in testicular tissue malnutrition(Harrison et al., 1983, 1986), retrograde bloodflow of adrenal/renal metabolites via the left
testicular vein (Javert and Clark, 1944), testicular hypoxia, testicular defects in glucose
metabolism (Sofikitis and Miyagawa, 1992),
alterations in the function/sensitivity of the
hypothalamo-pituitary-testicular axis (Weiss
and Rodriguez-Rigau, 1978), Sertoli cell anatomical defects (Snydle and Cameron, 1983) orsecretory dysfunction (Sofikitis and Miyagawa,
1992) and Leydig cell secretory dysfunction(Rajfer et al., 1987; Sofikitis et al., 1996).
Among these theories, elevation of testiculartemperature due to dysfunction in the countercurrent heat exchange system and testicular
tissue malnutrition are the only theories referring to fluid dynamics and the testicular vascular system. In the current study we attempteed
to investigate the influence of alterations intesticular tissue vasculature in the developmentof testicular damage induced by varicocele.
The present investigation confirms previous
studies showing that induction of left varicocele
in the rat leads to an increase in testicular temperature resulting in Leydig secretory dysfunction. Rajfer and coworkers (1987) have demonstrated that increase in testicular temperaturecausing dysfunction of 17,20 desmolase impairs intratesticular testosterone biosynthesis.
That study is consistent with the finding ofsignificantly smaller testosterone responses invaricocelized rats than in control rats in thecurrent study. It appears that during normal
conditions the diminished intratesticular
testosterone profiles are not reflected in theGroup

Number of vessels

A
14 ± 6B
20 ± 6C
23 ± 7
D
21 ± 7E
41 ± 11*F
46 ± 13*G
19 ± 5** indicates a significant difference (P < 0.05) compared with varicocele group A.

peripheral serum testosterone levels, whereas
when Leydig cells are hyperstimulated, the impaired Leydig cell secretory function in varicocelized rats is manifested by smaller testosterone responses to hCG stimulation. Thesefindings are also compatible with our previous
observations of the rabbit varicocele model(Sofikitis and Miyagawa, 1992, 1994; Sofikitis
et al., 1996). The Leydig cell secretory dysfunction in varicocelized rats may be responsible for the impaired spermatogenesis andepididymal maturation process manifested bysmaller epididymal cauda sperm content andmotility in the current study. It is known that
optimal concentrations of intratesticular andintraepididymal testosterone are important for
activating and maintaining the spermatogenesis
and epididymal sperm maturation process.
Considering that Leydig cell function influences Sertoli cell secretory function, which inturn affects spermatogenesis and the epididymal sperm maturation process, defects in
Sertoli cell secretory function may be present inrats with varicocele further impairing spermatogenesis and the epididymal sperm maturation
process. In fact, studies in varicocelized rabbits
have revealed anatomic (Snydle and Cameron,1983) and functional (Sofikitis and Miyagawa,
1992) defects in Sertoli cells.
The epididymal sperm maturation process isknown to involve a cascade of events resulting
in the development of the sperm’s capacity topenetrate and fertilize oocytes. Alterations inspermatozoal lipid and carbohydrate composition and transportation of spermatozoal
46

Vascularization and testicular function

cytoskelton proteins occur during the sperm’s
passage through the epididymis (Turner, 1979).
The subnormal/abnormal epididymal sperm
maturation process detrimentally affects theoverall sperm fertilizing capacity. Thus, thesmaller IVF outcome demonstrated in the current study in varicocelized rats may be due tothe inability of the epididymal lumen to induce
those alterations that secure optimal sperm fertilizing potential.
Previous studies of monkeys with varicocele (Harrison et al., 1983, 1986) have shown
an increase in intratesticular hydrostatic pressure. High intratesticular hydrostatic pressure
is expected to impair the exit of oxygen andnutrients from the arterial ends of capillaries
resulting in hypoxia and malnutrition. Hypoxia
and malnutrition can explain the hypospermatogenesis and Leydig cell and Sertoli cell dysfunction in patients and animals with varicocele(see review Sofikitis and Miyagawa, 1993).
We attempted to improve testicular spermatogenic and steroidogenic processes in the varicocelized rats by administering factors inducing
vascularization. Angiogenic factors are expected to improve tissue nutrition and restore hypoxia. The primary stimulus for neovascularization in the vast majority of tissues is hypoxia.
Hypoxia stimulates tissue cells to secrete several paracrine factors including VEGF that specifically induces proliferation of adjacent capillaries in the tissue (Hammes et al., 1996). In
response, endothelial cells acquire the angiogenic phenotype with a subsequent rearrangement of gene expression that leads to upregulation of downstream effector mechanisms suchas adhesion receptors (Bischoff, 1995) and pericellular proteolysis (Bacharach et al., 1992).
Other angiogenic factors include basic FGF,
IGF-I, TNF-α, angiotensin II and platelet derived growth factor.
Administration of each of the vascularizationinducing factors (VIFs) in varicocelized rats increased the number of vessels per seminiferous
tubule, but a significantly larger number of vessels was found only in rats treated with VEGF
or a combination of all the factors. Treatment
with a combination of VIFs, TNF-α and VEGF
significantly improved spermatogenesis and theepididymal sperm maturation process. The latter thesis is supported by the significant improvements in epididymal caudal sperm content, quantitative motility and qualitative motility. These improvements may be attributable toamelioration of Leydig cell secretory function
as indicated by the significantly larger values of
testosterone responses compared with varicocelized rats treated with saline. The large andsignificant improvement in Leydig cell secretory function in rats treated with a combinationof VIFs, TNF-α and VEGF is attributable to thesignificant increases in L∆T values comparedwith varicocelized rats treated with saline since
it is known that increase in testicular temperature detrimentally affects 17,20 desmolase
in Leydig cells (Rajfer et al., 1987). The improvement in testicular temperature regulationin varicocelized rats treated with a combinationof VIFs, TNF-α and VEGF is a finding of clinical importance and may be attributable to improvement in vascularization. If we adopt the
hypothesis of Harrison and coworkers (1981,1986), we are able to propose that improvement
in vascularization and an increase in the numberof testicular tissue capillaries decreases intratesticular hydrostatic pressure and ameliorates
the tissue edema known to occur in varicocelized subjects (Harrison et al., 1981, 1986). Improvement in fluid dynamics in varicocelized
rats may account for the improvement in thefunctionality of the vascular countercurrent
heat exchange system in the varicocelized testis
resulting in a decrease in testicular temperature.
Although improvements in epididymal
caudal sperm content and motility were significant only in varicocelized rats treated with a
combination of VIFs, TNF-α and VEGF, webelieve that administration of FGF or IGF-I also
improve (although in a smaller degree) the
function of varicocelized testis and the epididymal sperm maturation process. This is supported by the significantly larger testicular weightand IVF outcome in the groups of rats thatreceived FGF or IGF-I. Testicular weight isknown to correlate significantly with testicular
endocrine and exocrine function (Takihara etal., 1987) and in vitro sperm fertilizing capacity
is largely dependent on the efficiency of the47

T. Isoyama and N. Sofikitis

1992;89:10686–10690.
3 Bischoff J. Approaches to study cell adhesion
molecules in angiogenesis. Trens Cell Biol 1995;
5:69–74.
4 Coyotupa J, Parlow AF, Abraham GE. Simultaneous radioimmunoassay of plasma testosterone and dihydrotestosterone. Anal Lett 1972;
5:329–340.
5 Javert C, Clark R. Combined operation for varicocele and inguinal hernia:preliminary report.
Surg Gyn Obst 1944;79:644–650.
6 Hammes HP, Brownlee M, Jonczyk A, Sutter A,
Preissner KT. Subcutaneous injection of a cycle
peptide antagonist of vitronectin receptor type
integrins inhibit retinal vascularization. Nat Med
1996;2:529–533.
7 Harrison RM, Lewis RW, Roberts JA. Testicularblood flow and fluid dynamics in monkeys withsurgical induced varicoceles. J Androl 1983;4:
256–260.
8 Harrison RM, Lewis RW, Roberts JA. Pathophysiology of varicocele in non-human primates:
long term seminal and testicular changes. Fertil
Steril 1986;46:500–510.
9 MacLeod J. Seminal cytology in the presence ofvaricocele. Fertil Steril 1965;16:735–757.
10 Palermo G, Joris H, Devroey P, Van Steirteghem
AC. Pregnancy after intracytoplasmic injectionof a single spermatozoon into oocyte. Lancet
1992;340:17–18.
11 Rajfer J, Turner TT, Rivera S, Howards S, Sikka
S. Inhibition of testicular testosterone biosynthesis following experimental varicocele in rats.
Biol Reprod 1987;36:933–937.
12 Saypol DC, Howards SS, Turner TT, Miller ED.
Influence of surgically induced varicocele on testicular blood flow, temperature, and histology inadult rats and dogs. J Clin Invest 1981;68:39–45.
13 Sofikitis N, Mantzavinos T, Loutradis D,
Yamamoto Y, Tarlatzis V, Miyagawa I. Ooplasmic injections of secondary permatocytes for thetreatment of non-obstructive azoospermia.
Lancet 1998b;351:1177–1178.
14 Sofikitis N, Miyagawa I. Effects of surgical repair of experimental left varicocele on testiculartemperature, spermatogenesis, sperm maturation,
endocrine function, and fertility in rabbits. Arch
Androl 1992;29:163–175.
15 Sofikitis N, Miyagawa I. Experimental models
for the study of varicocele: a selected review. Jpn
J Fertil Steril 1993; 38:168–177.
16 Sofikitis N, Miyagawa I. Bilateral effect of
unilateral varicocele on testicular matabolism in
the rabbit. Int J Fertil 1994;39:239–247.
17 Sofikitis N, Miyagawa I, Incze P, Andrighetti S.
Detrimental effect of left varicocele on the reproductive potential of early haploid male gamete. J
Urol 1996;156:267–270.
18 Sofikitis N, Miyagawa I, Yamamoto Y, Loutradis

epididymal lumen to induce the necessary alterations in spermatozoa in order to achieve fertilizing capacity.
The current study shows that intrascrotal
administration of specific VIFs can induce neovascularization in the varicocelized testis, improve the efficiency of the vascular coutercurrent heat exchange system and subsequently
decrease testicular temperature. A decrease inL∆T in varicocelized rats is accompanied by
improvements in spermatogenesis, the epididymal sperm maturation process and testicular
steroidogenic capacity. Improvement in testicular tissue nutrition may also contribute to improvements in testicular and epididymal function. In addition, the present study is the firstreport in the literature providing an attractive
hypothesis to explain the presence of a subpopulation of fertile men with varicocele: men
with varicocele and abundant testicular vascularization may be able to a) have adequate
testicular nutrition, b) maintain a satisfactory
function of the countercurrent heat exchangesystem avoiding larger increases in testiculartemperature and c) alleviate the testicular edema proven to exist in men with varicocele.
Therefore, the varicocelized fertile men may beable to alleviate testicular tissue fluid dynamics
and compensate for the effects of the large
testicular venous pressure on the testis.
Acknowledgments: We thank Prof. I. Miyagawa(Dept. of Urology, Faculty of Medicine, Tottori University) for his kind advice and valuable suggestionsin this study, Prof. T. Terada (Second Dept. of Pathology, Faculty of Medicine, Tottori University)and Prof. J. Hasegawa (Dept. of Clinical Pharmacology, Faculty of Medicine, Tottori University) for
their kind advice in correcting this manuscript.

References
1 Amelar RD, Dubin L. Right varicocelectomy inselected infertile patients who have failed to improve after previous left varicocelectomy. Fertil
Steril 1987;47:833–837.
2 Bacharach E, Itin A, Keshet E. In vivo patternsof expression of urokinase and its inhibitor PAI-1
suggest a concerted role in regulating physiological angiogenesis. Proc Natl Acad Sci USA

48

Vascularization and testicular function

D, Mantzavinos T, Tarlatzis V. Micro- andmacro-consequences of ooplasmic injections ofearly haploid male gametes. Hum Reprod Update
1998a;4:197–212.
19 Sofikitis N, Takahashi C, Kadowaki H, Okazaki
T, Nakamura I, Shimamoto T, et al. Surgical repair versus medical treatment of varicocele in the
rat Pharmacological manipulation of the varicocelized testicle. Eur Urol 1992b;22:44–52.
20 Sofikitis N, Takahashi C, Nakamura I, Hirakawa
S, Miyagawa I. Surgical repair of secondary rightvaricocele in rat with primary left varicocele: effects on fertility, testicular temperature, spermatogenesis, and sperm maturation. Arch Androl
1992a;28:43–52.
21 Snydle FE, Cameron DF. Surgical induction ofvaricocele in the rabbit. J Urol 1983;130:1005–
1009.
22 Takihara H, Cosentino MJ, Sakatoku J, Cockett

AT. Significance of testicular size mesurement
in andrology: II. Correlation of testicular sizewith testicular function. J Urol 1987;137:416–
419.
23 Toyoda Y, Chang MC. Fertilization of rat eggs invitro by epididymal spermatozoa and the development of eggs following transfer. J Reprod
Fertil 1974;36:9–22.
24 Turner TT. On the epididymis and its function.
Invest Urol 1979;16:311–321.
25 Turner TT. Varicocele: still an enigma. J Urol
1983;129:695–699.
26 Weiss DB, Rodriguez-Rigau LJ, Smith KD.
Leydig cell function in oligospermic men withvaricocele. J Urol 1978;120:427–430.
27 Yamamoto Y, Isoyama E, Sofikitis N, Miyagawa
I. Effects of smoking on testicular function andfertilizing potential in rats. Urol Res 1998;26:
45–48.

(Received December 18, Accepted December 24, 1998)

49