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Comparison of Blood Flow and Histological Changes in Rat Models of Testicular Ischemia
0022-5347/97/1583-1138$03.00/0 THEJOLWALOF UROUXX Copyright 0 1997 by AMERICW UROLOGIC.% ASSOCIATICIS. 1%~.
Vol. 158,1138-1140,September 1997 Printed in U S A .
COMPARISON OF BLOOD FLOW AND HISTOLOGICAL CHANGES IN RAT MODELS OF TESTICULAR ISCHEMIA JEFFREY S. PALMER, LOUIS F. PLZAK From the Section
of
AND
WILLIAM J. CROMIE
Urology, University of Chicago Pritzker School of Medicine, Chicago, Illinois
ABSTRACT
Purpose: Our aim was to quantify objectively the degree of vascular insufficiency produced by twisting versus clamping the spermatic cord, and determine the contribution of the vasal vessels to these changes using the laser Doppler flowmeter. Materials and Methods: Three groups of 12 male Sprague-Dawley rats each were studied. Group 1 underwent 720-degree torsion of the spermatic cord, group 2 underwent vascular clamping of the spermatic cord with 1clamp, excluding the anatomically separate vasal vessels, and group 3 underwent vascular clamping of the entire spermatic cord and vasal vessels with 2 clamps. Blood flow and histological changes were determined. Results: Vascular clamping of the spermatic cord in groups 2 and 3 resulted in a significant decrease in testicular blood flow compared to 720-degree torsion (p c0.05).These flow changes correlated with more severe and reproducible gross changes, and histological features of seminiferous tubule degeneration compared to spermatic cord twisting. Conclusions: In the rat clamping the spermatic cord is a more severe and reproducible model of testicular torsion than 720-degree torsion. The contribution of the vasal vessels to the decrease in blood flow and resulting histological degeneration after testicular ischemia is negligible in the rat. KEYWORDS:testis; spermatic cord torsion; reperfusion;rats, Sprague-Dawley;ischemia Testicular torsion most commonly results from develop- spermatic cord and vasal vessels separately with 2 clamps mental hypermobility caused by a redundant or elongated (fig. 1). tunica vaginalis, known a s the bell clapper deformity. This Blood flow changes. In all 3 groups the left testicle was urological emergency can lead to testicular necrosis and de- delivered from the hemiscrotum through a left scrota1 incicreased fertility.’-4 For this reason histological changes as- sion and visually monitored throughout the experiment. A sociated with decreased testicular blood flow have been ex- laser Doppler flowmeter was used to record ipsilateral testensively studied.5-7 Two rat models have been traditionally ticular blood flow a t 1-minute intervals in 6 animals in each used to investigate testicular torsion, including 720-degree group. Measurements were obtained by placing a cutaneous torsion6 and vascular cross clamping of the whole spermatic laser Doppler probe on the mid lateral aspect of the exposed cord plus the vessels of the vas deferens.5 Potential differ- testicle, where no visible large arteries or veins were present. ences between these 2 models, such as reproducibility and The probe was maintained in a fured position using a tripod physiological effect, make data interpretation difficult among stand. Blood flow was determined at baseline for 10 minutes, studies. The purpose of our study was to use the laser Doppler flowmeter to quantify objectively the degree of vas- during ischemia for 20 minutes and during reperfusion for 10 cular insufficiency produced by each model and determine minutes. Reperfusion was accomplished by untwisting the contribution of the vasal vessels to these changes. In (group 1)or unclamping (groups 2 and 3) the spermatic cord. addition, histological changes associated with each model Analysis of variance and the Fisher protected t test were were evaluated. Ideally information concerning differences in used to determine statistical significance a t p <0.05. Histological changes. An additional 6 rats in each group these models would serve to help interpret existing data underwent 4 hours of ischemia to determine histological feabetter and allow methodological uniformity in the future. tures produced by each model. Saline moistened gauze was used to prevent desiccation of the exposed testicle. At the end MATERIALS A N D METHODS of the experiment both testicles were surgically removed, Male Sprague-Dawley adult rats weighing 293 to 605 gm. fwed in 10% buffered formalin, embedded in paraffin, secwere anesthetized with 90 mg./kg. ketamine and 10 mg./kg. tioned a t 3 p., and stained with hematoxylin and eosin. An xylazine intraperitoneally. The left and right testicles served independent pathologist evaluated and compared specific as the experimental and contralateral control gonads, respec- histological parameters, including germ cell layer degeneratively. Animals were randomly separated into 3 groups of 12 tion (nuclear chromicity) and disarray, nuclear debris, cellueach. Group 1 (720-degree model) underwent 720-degree tor- lar cohesiveness, and Sertoli’s and Leydig cell degeneration sion of the spermatic cord, group 2 (1-clamp model) under- with germ cell degeneration as the primary determinant. In went vascular clamping of the spermatic cord with 1 clamp, addition, the diameters of 10 randomly selected circular semexcluding the anatomically separate vasal vessels,8 and iniferous tubules were measured from a single longitudinal group 3 (2-clamp model) underwent vascular clamping of the histological section of each testicle to prevent counting repetitive tubules. All specimens were coded to guarantee blinded Supported in part by a research grant from Ronald McDonald determination of the seminiferous tubular diameters. AnalHouse Chanties. ysis of variance and 2-sample t testing assuming unequal 1138
BLOOD FLOW AN11 TES'I'ICULAR CHANGES IN TESTICIJIAH IS('ItEM1A
1139
contralateral control testicular diameter) was significantly greater in t h e clamped than in t h e torsion group. However, no significant difference in tubular diameter was noted between groups 2 and 3. Also, in t h e experimental testicles of the 2 group 1 rats (33.3%)with normal macroscopic and microscopic findings mean seminiferous tubular diameter was similar to that of the respective contralateral control gonads. DISCUSSION
FIG. 1. Animal model of testicular torsion investigated
variance were used to determine statistical significance at p C0.05. RESULTS
Blood flow changes (fig. 2). All 3 models of testicular torsion resulted in a significant decrease in blood flow ( p <0.05) that reached a plateau within 10 minutes of ischemia and then returned to baseline within 10 minutes of reperfusion. However, clamping in groups 2 and 3 resulted in a significantly greater ( p <0.05) decrease in testicular blood flow (81.6 and 85.8%,, respectively) than torsion in group 1 (61.79). No significant difference was noted between groups 2 and 3. Macroscopic and microscopic changes (figs. 3 and 4). After 4 hours of ischemia ipsilateral testes in all 3 groups had findings consistent with acute ischemia. Macroscopically these testicles demonstrated hemorrhagic discoloration and vascular congestion. Microscopically they had decreased nuclear chromicity and disarray of the germ cell layers, cellular debris and a lack of cellular cohesiveness. No histological evidence of Leydig or Sertoli's cell degeneration was noted. These macroscopic and microscopic changes were always present in t h e clamped groups and more severe than after spermatic cord torsion. However, these findings were not noted in 2 of the 6 testes (33%)in group 1. In these 2 rats there were no significant macroscopic or microscopic differences in t h e ischemic versus the contralateral control testicles. There were no abnormal macroscopic changes, such as abnormal coloration or vascular congestion, or microscopic findings, such as abnormal nuclear chromicity, germ cell organization or cellular cohesiveness, in the contralateral control testicles in all 3 groups. Seminiferous tubular diameter (see table). The difference in seminiferous tubular diameter between experimental and control testicles (experimental testicular diameter minus
-
20
0"
15
E
The goal of testicular torsion intervention is salvage of the gonad. Gonads must undergo reperfusion within 4 to 6 hours to optimize testicular viability.l,fi To evaluate the biochemical and/or immunological alterations associated with changes in histology and fertility, a severe reproducible animal model of testicular ischemia must be established that considers testicular blood supply and t h e pathophysiology of torsion. Several animal models of testicular ischemia have been de~ e l o p e d . s . 6 ~However, S~~ 2 models have persisted in the literature t h a t compromise arterial and venous flow using differe n t techniques.s,6 To our knowledge the significance of this difference and its reproducibility have not been investigated, making data interpretation difficult among studies. Therefore, the goal of our series was to compare alterations in testicular blood flow and histology in the 2 classic models of 720-degree torsion and 2 clamps as well as in the model of 1 clamp on the spermatic cord with patent vasal vessels.8 As previously established, the laser Doppler flowmeter was used to quantitate blood flow during episodes of ischemia and reperfusion for each model.10-12 This method provides a continuous evaluation of tissue blood flow without affecting tissue physiology.10 This modality determines flow by delivering a low power beam of laser light to the tissue using fiber optics. Moving red blood cells in the tissue cause a shift in photon Doppler frequency. Optical fibers collect the light signals, digitally process t h e signals and determine average blood flow. The laser Doppler flowmeter offers several advantages compared to other techniques. Continuous blood flow rnonitoring is possible, unlike in t h e microsphere and isotope methods. Unlike methods using thermal clearance, the laser Doppler flowmeter does not cause any recordable heating effect on the tissue. Therefore, since measurement does not affect blood flow, it reflects the physiology of the tissue evaluated. Unlike other methods of continuous determination of blood flow, such as electromagnetic flow and ultrasonic measurements, this method documents blood flow through capillaries rather than large vessels. Our study demonstrated several significant advantages of the clamped over the torsion model. Vascular clamping of t h e
0 \ Y
C
-E
10
MODELS -720-degree -0- 1clamp 2clamp
:
-
-VJ LL
0 Baseline
1
2
3
4
1
2
Time interval (x 5 minutes) FIG. 2. Testicular blood flow changes during 20 minutes of ischemia and 10 minutes of reperfusion
1140
BLOOD FLOW AND TESTICULAR CHANGES IN TESTICULAR ISCHEMIA
FIG. 4. Microscopic findings. A, normal nuclear chromicity, organization of germ cell layers and cell cohesiveness in contralateral testes in groups 1 to 3 and bilaterally in 33% of group 1.B, decreased nuclear chromicity, disarray of germ cell layers, lack of cell cohesiveness and cellular debris in 67% of ischemic testicles in group 1. C and D,more severe degrees of histological changes in ischemic testes in groups 2 and 3, respectively, versus group 1. H & E, reduced from X600. Seminiferous tubular diameter in groups I to 3 Groups
Mean Experimental - Control Diameter t SEM 1 u.1
-8.2 t 3.8 i_ 2.9*
1
-26.8 -29.2 ~
2
7 z. 4.. .?* ~ * Analysis of variance and 2-sample t test assuming unequal variance p 10.05
versus gmup 1. Group 2 versus 3 was not sigruficantly different (p >0.05).
quired to delineate further the most accurate model of testicular torsion. Dr.Anthony G. Montag evaluated the histological sections and Dr. Theodore Karrison performed the statistical analysis. REFERENCES
FIG. 3. Macroscopic findings. A, normal coloration and no vascular congestion bilaterally in 33% of group 1 animals. B , hemorrhagic discoloration and vascular congestion in 67% of group 1 ischemic testicles. C , more severe hemorrhagic discoloration and vascular congestion in ischemic testicles in groups 2 and 3 versus 1.
spermatic cord in groups 2 and 3 produced a more severe and reproducible decrease in blood flow than 720-degree torsion in group 1 (fig. 2). These flow changes correlated with macroscopic and microscopic ischemic changes (figs. 3 and 4). There were more severe gross changes and histological features consistent with seminiferous tubule degeneration in the clamped than in the torsion group. No significant difference was noted between the clamped groups. These changes were always present in the clamped groups but not in 33%of the 720-degree group. Therefore, based on this interval of testicular torsion (4 hours), 720 degrees of torsion are not as stringent a model as cord clamping. However, the validity of this torsion model for longer duration of torsion cannot be extrapolated from this study. Using these techniques we also demonstrated that preservation of the vasal vessels did not significantly alter blood flow, or affect gross morphology or histology compared to complete spermatic cord clamping. However, the effects of vasal vessel patency cannot be ruled out at a molecular or biochemical level. Therefore, additional investigation is re-
1. Krarup, T.: The testes after torsion. Brit. J . Urol., 50: 43, 1978. 2. Bartsch, G., Frank, S., Marberger, H. and Mikuz, G.: Testicular torsion: late results with special regard to fertility and endocrine function. J . Urol., 124: 375, 1980. 3. Goldwasser, B., Weissenberg, R., Lunenfeld, B., Nativ, 0. and Many, M.: Semen quality and hormonal status of patients following testicular torsion. Andrologia, 1 6 239, 1984. 4. Thomas, W. E. G., Cooper, M. J., Crane, G. A., Lee, G. and Williamson, R. C. N.: Testicular exocrine malfunction after torsion. Lancet, 2 1357, 1984. 5. Smith, G. I.: Cellular changes from graded testicular ischemia. J . Urol., 73: 355, 1955. 6. Sonda, L. P., J r . and Lapides, J.: Experimental torsion of the spermatic cord. Surg. For., 1 2 502, 1961. 7. Cosentino, M. J., Nishida, M., Rabinowitz, R. and Cockett, A. T. K.: Histopathology of prepubertal rat testes subjected to various durations of spermatic cord torsion. J . Androl., 7: 23, 1986. 8. Oettle, A. G. and Harrison, R. G.: The histological changes produced in the rat testis by temporary and permanent occlusion of the testicular artery. J . Path. Bacteriol., 64:273, 1955. 9. Griffths, J.: The effects upon the testes of ligature of the spermatic artery, spermatic veins, and of both artery and veins. J . Anat., 3 0 81, 1896. 10. Damber, J.-E., Lindahl, O., Selstam, G. and Tenland, T.: Testicular blood flow measured with a laser Doppler flowmeter: acute effects of catecholamines. Acta Physiol. Scand., 1 1 5 209, 1982. 11. Bergh, A. and Damber, J.-E.: Does unilateral orchidectomy influence blood flow, microcirculation and vascular morphology in the remaining testis? Int. J . Androl., 14: 453, 1991. 12. Collin, 0.. Bergh, A,, Damber, J.-E. and Widmark, A,: Control of testicular vasomotion by testosterone and tubular factors in rats. J . Reprod. Fertil., 97: 115, 1993.
Vol. 158,1138-1140,September 1997 Printed in U S A .
COMPARISON OF BLOOD FLOW AND HISTOLOGICAL CHANGES IN RAT MODELS OF TESTICULAR ISCHEMIA JEFFREY S. PALMER, LOUIS F. PLZAK From the Section
of
AND
WILLIAM J. CROMIE
Urology, University of Chicago Pritzker School of Medicine, Chicago, Illinois
ABSTRACT
Purpose: Our aim was to quantify objectively the degree of vascular insufficiency produced by twisting versus clamping the spermatic cord, and determine the contribution of the vasal vessels to these changes using the laser Doppler flowmeter. Materials and Methods: Three groups of 12 male Sprague-Dawley rats each were studied. Group 1 underwent 720-degree torsion of the spermatic cord, group 2 underwent vascular clamping of the spermatic cord with 1clamp, excluding the anatomically separate vasal vessels, and group 3 underwent vascular clamping of the entire spermatic cord and vasal vessels with 2 clamps. Blood flow and histological changes were determined. Results: Vascular clamping of the spermatic cord in groups 2 and 3 resulted in a significant decrease in testicular blood flow compared to 720-degree torsion (p c0.05).These flow changes correlated with more severe and reproducible gross changes, and histological features of seminiferous tubule degeneration compared to spermatic cord twisting. Conclusions: In the rat clamping the spermatic cord is a more severe and reproducible model of testicular torsion than 720-degree torsion. The contribution of the vasal vessels to the decrease in blood flow and resulting histological degeneration after testicular ischemia is negligible in the rat. KEYWORDS:testis; spermatic cord torsion; reperfusion;rats, Sprague-Dawley;ischemia Testicular torsion most commonly results from develop- spermatic cord and vasal vessels separately with 2 clamps mental hypermobility caused by a redundant or elongated (fig. 1). tunica vaginalis, known a s the bell clapper deformity. This Blood flow changes. In all 3 groups the left testicle was urological emergency can lead to testicular necrosis and de- delivered from the hemiscrotum through a left scrota1 incicreased fertility.’-4 For this reason histological changes as- sion and visually monitored throughout the experiment. A sociated with decreased testicular blood flow have been ex- laser Doppler flowmeter was used to record ipsilateral testensively studied.5-7 Two rat models have been traditionally ticular blood flow a t 1-minute intervals in 6 animals in each used to investigate testicular torsion, including 720-degree group. Measurements were obtained by placing a cutaneous torsion6 and vascular cross clamping of the whole spermatic laser Doppler probe on the mid lateral aspect of the exposed cord plus the vessels of the vas deferens.5 Potential differ- testicle, where no visible large arteries or veins were present. ences between these 2 models, such as reproducibility and The probe was maintained in a fured position using a tripod physiological effect, make data interpretation difficult among stand. Blood flow was determined at baseline for 10 minutes, studies. The purpose of our study was to use the laser Doppler flowmeter to quantify objectively the degree of vas- during ischemia for 20 minutes and during reperfusion for 10 cular insufficiency produced by each model and determine minutes. Reperfusion was accomplished by untwisting the contribution of the vasal vessels to these changes. In (group 1)or unclamping (groups 2 and 3) the spermatic cord. addition, histological changes associated with each model Analysis of variance and the Fisher protected t test were were evaluated. Ideally information concerning differences in used to determine statistical significance a t p <0.05. Histological changes. An additional 6 rats in each group these models would serve to help interpret existing data underwent 4 hours of ischemia to determine histological feabetter and allow methodological uniformity in the future. tures produced by each model. Saline moistened gauze was used to prevent desiccation of the exposed testicle. At the end MATERIALS A N D METHODS of the experiment both testicles were surgically removed, Male Sprague-Dawley adult rats weighing 293 to 605 gm. fwed in 10% buffered formalin, embedded in paraffin, secwere anesthetized with 90 mg./kg. ketamine and 10 mg./kg. tioned a t 3 p., and stained with hematoxylin and eosin. An xylazine intraperitoneally. The left and right testicles served independent pathologist evaluated and compared specific as the experimental and contralateral control gonads, respec- histological parameters, including germ cell layer degeneratively. Animals were randomly separated into 3 groups of 12 tion (nuclear chromicity) and disarray, nuclear debris, cellueach. Group 1 (720-degree model) underwent 720-degree tor- lar cohesiveness, and Sertoli’s and Leydig cell degeneration sion of the spermatic cord, group 2 (1-clamp model) under- with germ cell degeneration as the primary determinant. In went vascular clamping of the spermatic cord with 1 clamp, addition, the diameters of 10 randomly selected circular semexcluding the anatomically separate vasal vessels,8 and iniferous tubules were measured from a single longitudinal group 3 (2-clamp model) underwent vascular clamping of the histological section of each testicle to prevent counting repetitive tubules. All specimens were coded to guarantee blinded Supported in part by a research grant from Ronald McDonald determination of the seminiferous tubular diameters. AnalHouse Chanties. ysis of variance and 2-sample t testing assuming unequal 1138
BLOOD FLOW AN11 TES'I'ICULAR CHANGES IN TESTICIJIAH IS('ItEM1A
1139
contralateral control testicular diameter) was significantly greater in t h e clamped than in t h e torsion group. However, no significant difference in tubular diameter was noted between groups 2 and 3. Also, in t h e experimental testicles of the 2 group 1 rats (33.3%)with normal macroscopic and microscopic findings mean seminiferous tubular diameter was similar to that of the respective contralateral control gonads. DISCUSSION
FIG. 1. Animal model of testicular torsion investigated
variance were used to determine statistical significance at p C0.05. RESULTS
Blood flow changes (fig. 2). All 3 models of testicular torsion resulted in a significant decrease in blood flow ( p <0.05) that reached a plateau within 10 minutes of ischemia and then returned to baseline within 10 minutes of reperfusion. However, clamping in groups 2 and 3 resulted in a significantly greater ( p <0.05) decrease in testicular blood flow (81.6 and 85.8%,, respectively) than torsion in group 1 (61.79). No significant difference was noted between groups 2 and 3. Macroscopic and microscopic changes (figs. 3 and 4). After 4 hours of ischemia ipsilateral testes in all 3 groups had findings consistent with acute ischemia. Macroscopically these testicles demonstrated hemorrhagic discoloration and vascular congestion. Microscopically they had decreased nuclear chromicity and disarray of the germ cell layers, cellular debris and a lack of cellular cohesiveness. No histological evidence of Leydig or Sertoli's cell degeneration was noted. These macroscopic and microscopic changes were always present in t h e clamped groups and more severe than after spermatic cord torsion. However, these findings were not noted in 2 of the 6 testes (33%)in group 1. In these 2 rats there were no significant macroscopic or microscopic differences in t h e ischemic versus the contralateral control testicles. There were no abnormal macroscopic changes, such as abnormal coloration or vascular congestion, or microscopic findings, such as abnormal nuclear chromicity, germ cell organization or cellular cohesiveness, in the contralateral control testicles in all 3 groups. Seminiferous tubular diameter (see table). The difference in seminiferous tubular diameter between experimental and control testicles (experimental testicular diameter minus
-
20
0"
15
E
The goal of testicular torsion intervention is salvage of the gonad. Gonads must undergo reperfusion within 4 to 6 hours to optimize testicular viability.l,fi To evaluate the biochemical and/or immunological alterations associated with changes in histology and fertility, a severe reproducible animal model of testicular ischemia must be established that considers testicular blood supply and t h e pathophysiology of torsion. Several animal models of testicular ischemia have been de~ e l o p e d . s . 6 ~However, S~~ 2 models have persisted in the literature t h a t compromise arterial and venous flow using differe n t techniques.s,6 To our knowledge the significance of this difference and its reproducibility have not been investigated, making data interpretation difficult among studies. Therefore, the goal of our series was to compare alterations in testicular blood flow and histology in the 2 classic models of 720-degree torsion and 2 clamps as well as in the model of 1 clamp on the spermatic cord with patent vasal vessels.8 As previously established, the laser Doppler flowmeter was used to quantitate blood flow during episodes of ischemia and reperfusion for each model.10-12 This method provides a continuous evaluation of tissue blood flow without affecting tissue physiology.10 This modality determines flow by delivering a low power beam of laser light to the tissue using fiber optics. Moving red blood cells in the tissue cause a shift in photon Doppler frequency. Optical fibers collect the light signals, digitally process t h e signals and determine average blood flow. The laser Doppler flowmeter offers several advantages compared to other techniques. Continuous blood flow rnonitoring is possible, unlike in t h e microsphere and isotope methods. Unlike methods using thermal clearance, the laser Doppler flowmeter does not cause any recordable heating effect on the tissue. Therefore, since measurement does not affect blood flow, it reflects the physiology of the tissue evaluated. Unlike other methods of continuous determination of blood flow, such as electromagnetic flow and ultrasonic measurements, this method documents blood flow through capillaries rather than large vessels. Our study demonstrated several significant advantages of the clamped over the torsion model. Vascular clamping of t h e
0 \ Y
C
-E
10
MODELS -720-degree -0- 1clamp 2clamp
:
-
-VJ LL
0 Baseline
1
2
3
4
1
2
Time interval (x 5 minutes) FIG. 2. Testicular blood flow changes during 20 minutes of ischemia and 10 minutes of reperfusion
1140
BLOOD FLOW AND TESTICULAR CHANGES IN TESTICULAR ISCHEMIA
FIG. 4. Microscopic findings. A, normal nuclear chromicity, organization of germ cell layers and cell cohesiveness in contralateral testes in groups 1 to 3 and bilaterally in 33% of group 1.B, decreased nuclear chromicity, disarray of germ cell layers, lack of cell cohesiveness and cellular debris in 67% of ischemic testicles in group 1. C and D,more severe degrees of histological changes in ischemic testes in groups 2 and 3, respectively, versus group 1. H & E, reduced from X600. Seminiferous tubular diameter in groups I to 3 Groups
Mean Experimental - Control Diameter t SEM 1 u.1
-8.2 t 3.8 i_ 2.9*
1
-26.8 -29.2 ~
2
7 z. 4.. .?* ~ * Analysis of variance and 2-sample t test assuming unequal variance p 10.05
versus gmup 1. Group 2 versus 3 was not sigruficantly different (p >0.05).
quired to delineate further the most accurate model of testicular torsion. Dr.Anthony G. Montag evaluated the histological sections and Dr. Theodore Karrison performed the statistical analysis. REFERENCES
FIG. 3. Macroscopic findings. A, normal coloration and no vascular congestion bilaterally in 33% of group 1 animals. B , hemorrhagic discoloration and vascular congestion in 67% of group 1 ischemic testicles. C , more severe hemorrhagic discoloration and vascular congestion in ischemic testicles in groups 2 and 3 versus 1.
spermatic cord in groups 2 and 3 produced a more severe and reproducible decrease in blood flow than 720-degree torsion in group 1 (fig. 2). These flow changes correlated with macroscopic and microscopic ischemic changes (figs. 3 and 4). There were more severe gross changes and histological features consistent with seminiferous tubule degeneration in the clamped than in the torsion group. No significant difference was noted between the clamped groups. These changes were always present in the clamped groups but not in 33%of the 720-degree group. Therefore, based on this interval of testicular torsion (4 hours), 720 degrees of torsion are not as stringent a model as cord clamping. However, the validity of this torsion model for longer duration of torsion cannot be extrapolated from this study. Using these techniques we also demonstrated that preservation of the vasal vessels did not significantly alter blood flow, or affect gross morphology or histology compared to complete spermatic cord clamping. However, the effects of vasal vessel patency cannot be ruled out at a molecular or biochemical level. Therefore, additional investigation is re-
1. Krarup, T.: The testes after torsion. Brit. J . Urol., 50: 43, 1978. 2. Bartsch, G., Frank, S., Marberger, H. and Mikuz, G.: Testicular torsion: late results with special regard to fertility and endocrine function. J . Urol., 124: 375, 1980. 3. Goldwasser, B., Weissenberg, R., Lunenfeld, B., Nativ, 0. and Many, M.: Semen quality and hormonal status of patients following testicular torsion. Andrologia, 1 6 239, 1984. 4. Thomas, W. E. G., Cooper, M. J., Crane, G. A., Lee, G. and Williamson, R. C. N.: Testicular exocrine malfunction after torsion. Lancet, 2 1357, 1984. 5. Smith, G. I.: Cellular changes from graded testicular ischemia. J . Urol., 73: 355, 1955. 6. Sonda, L. P., J r . and Lapides, J.: Experimental torsion of the spermatic cord. Surg. For., 1 2 502, 1961. 7. Cosentino, M. J., Nishida, M., Rabinowitz, R. and Cockett, A. T. K.: Histopathology of prepubertal rat testes subjected to various durations of spermatic cord torsion. J . Androl., 7: 23, 1986. 8. Oettle, A. G. and Harrison, R. G.: The histological changes produced in the rat testis by temporary and permanent occlusion of the testicular artery. J . Path. Bacteriol., 64:273, 1955. 9. Griffths, J.: The effects upon the testes of ligature of the spermatic artery, spermatic veins, and of both artery and veins. J . Anat., 3 0 81, 1896. 10. Damber, J.-E., Lindahl, O., Selstam, G. and Tenland, T.: Testicular blood flow measured with a laser Doppler flowmeter: acute effects of catecholamines. Acta Physiol. Scand., 1 1 5 209, 1982. 11. Bergh, A. and Damber, J.-E.: Does unilateral orchidectomy influence blood flow, microcirculation and vascular morphology in the remaining testis? Int. J . Androl., 14: 453, 1991. 12. Collin, 0.. Bergh, A,, Damber, J.-E. and Widmark, A,: Control of testicular vasomotion by testosterone and tubular factors in rats. J . Reprod. Fertil., 97: 115, 1993.