Testicular Biopsy Score Count After Vasectomy in Albino Rats

Context: One of the challenging problems faced by the entire world is population explosion. The vasectomy is simple, safe, quick and effective vital method of male sterilization. In the recent years a large number of vasectomies have been performed in India, since the inception of National Family Planning Program in 1956. Thus the number of request for the restoration of fertility is also increased. Aim: The present study was carried out to know whether the testicular biopsy score count, indicating the process of spermatogenesis remains normal after vasectomy. Material & Methods: The testicular biopsy count of testes of 50 male albino rats was studied one, two, three and four months after vasectomy, in 10 male albino rats of each case and 10 male albino rats served as control. Result: After vasectomy seminiferous tubules are cut in various planes covered externally by connective tissue stroma with normal microscopic picture. The spermatogonia, spermatocytes, spermatids, Sertoli cells and spermatozoa show normal structure with normal size blood vessels in interstitial connective tissue, in vasectomised and control rats. In some seminiferous tubules granular cytoplasmic vesicle like structures are seen filling the lumen and spermatids in metamorphosis phase to spermatozoa. Many round or elongated heads of spermatozoa are present at apical portion of Sertoli cells. The control rats as well as vasectomised rats at four after vasectomy have shown the testicular biopsy score count of nine (9) and ten (10) on TBSC of Johenson. Conclusion: On critical analysis it is concluded that the testicular biopsy score count remains normal at four months after vasectomy.     

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

Background

The effects of vasectomy on spermatogenesis and reproductive parameters are recognized to be specie-dependent with marked differences in levels of perturbations observed.

Objectives

To assess the impact of unilateral vasectomy on testosterone level and other testicular parameters in the male African giant rat (AGR) (Cricetomys gambianus).

Methods

Sixteen adult male AGRs weighing 500–1300 g were recruited for the experiment. Animals were randomly divided into three experimental groups (1–3) and one control (sham operated) group with four rats per group. Experimental vasectomy was done by carefully ligating the vas deferens of the right testis of all the experimental groups (1, 2, and 3) and animals were allowed either 8, 6 and 2 weeks respectively before sacrifice. Sham-operated animals served as the control. Blood samples were collected and assayed for testosterone while testicular tissue was further processed for seminal fluid and histo-pathological analyses.

Results

Spermatogenic parameters indicate a pattern of decline in sperm count and motility between the experimental groups and the control and azoospermia in the eight-week group. Histological alterations were marked by atrophy of seminiferous tubules which was proportional to the duration of vasectomy. Serum testosterone levels were significantly reduced at eight weeks. There was no statistically significant difference between sperm counts of right and left testes except for group 3. Results suggest that unilateral vasectomy of the AGR may have negative impact on the contralateral testis in the male African giant rat.

Conclusion

These preliminary results reveal that unilateral vasectomy in the AGR may result in perturbations of the histo-architecture of the testes with possible decline in function.     

Importance of the testicular artery: histo-functional approach and comparison between juvenile and adult rats

The aim of this study is to demonstrate the role of spermatic or testicular artery with regard to fertility. 100 male rats Sprague-Dawley, consisted of 50 young rats (aged from 10 to 12 days old) and 50 adult rats were concerned. Unilateral ligation of the testicular artery with delayed controlateral orchiectomy were performed in 20 young rats. Only unilateral orchiectomy was planned in 20 other young rats and the 10 remaining were the absolute control group. Mating was observed for 2 weeks after 14 weeks of life. In adult rats, 20 underwent a bilateral ligation and division of the spermatic artery while 20 others were submitted to unilateral ligation-division associated with controlateral orchiectomy in 20 others. The 10 remaining represented the control group. The mating period was 3 weeks. After sacrificing animals, results were noted with regard to histological features and fertility. Among young rats, 45% were fertile and had normal gonadal tissue. From adult rats, only 10 to 15% were fertile. Atrophic testes were observed in 55% of infertile young rats while acute inflammatory lesions were predominant in most of adults. We conclude that ligation or division of spermatic artery is responsible for histological changes thus occurring in infertility in young and adults rats.     

输精管结扎对大鼠睾丸、附睾及血清睾酮的中长期影响

目的：建立动物模型，观测输精管结扎中、长期对血清睾酮水平及睾丸和附睾的形态学影响，为评估输精管结扎术这一男性节育主要手段提供某些基础理论依据。方法：随机将40只4月龄Wistar大鼠，按4个等长的实验间期分为结扎组和对照组，在术后第4、6、8、10月时分别测定结扎组和对照组的血清睾酮(sT)浓度及其与雄激素结合蛋白(ABP)的结合率；在对受试动物的睾丸和附睾进行组织学定性观察的同时，用TAS-plus型自动图像分析仪，对睾丸切片进行了定量组织学测定。结果：除第4月实验组和对照组外，其他3个间期的实验组和对照组血清睾酮浓度均有显著变化；实验组睾丸和附睾均有无菌性炎症发生，且未随术后时间的延长而缓解。结论：结扎术对受试动物的中长期影响值得关注。     

不同药物对青春前期大鼠睾丸扭转复位健侧睾丸的远期影响

目的:观察牛磺酸、丹血通(丹参联合血栓通)和灯盏花素对青春前期大鼠睾丸扭转复位后健侧睾丸的远期影响及其保护作用,比较3种药物对抗睾丸缺血再灌注损伤的保护作用。方法:64只4周龄健康雄性SD大鼠,随机分为假手术组、模型组、牛磺酸单次和连续给药组、丹血通单次和连续给药组以及灯盏花素单次和连续给药组,每组8只,建立左侧睾丸扭转复位动物模型(720°,2 h)。于术后6周处死大鼠,取右侧睾丸及附睾,检测睾丸组织总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)活性、一氧化氮合酶(NOS)活性和丙二醛(MDA)含量,测定精子畸形率和精子活动率和精子浓度,行睾丸组织病理学观察。结果:与模型组相比,3个连续组的SOD活性、TAOC、精子活动率和精子浓度均增加,MDA含量和精子畸形率均降低(P0.05)。3个单次组的SOD活性和精子活动率(除灯盏花素单次组)均增加,MDA含量和精子畸形率均降低,牛磺酸单次组T-AOC和精子浓度增加(P0.05)。模型组可见生精小管退变,间质水肿,其它给药组睾丸扭转复位诱发的组织学改变明显改善。结论:青春前期大鼠单侧睾丸扭转复位后可致健侧睾丸缺血再灌注损伤,牛磺酸、丹血通和灯盏花素均对青春前期大鼠睾丸扭转复位后健侧睾丸远期功能恢复起到一定的保护作用,其作用效果牛磺酸明显优于丹血通和灯盏花素,丹血通明显优于灯盏花素,且连续给药明显优于单次给药。     

Protective effects of Ginkgo biloba (EGb 761) on testicular torsion/detorsion-induced ischemia-reperfusion injury in rats

The aim of this study was to investigate the protective effect of Ginkgo biloba (EGb 761) on testicular torsion/detorsion induced ischemia-reperfusion (I/R) injury. A total of 24 male Wistar albino rats were divided into three groups: control, I/R and I/R treated with EGb 761; each group contains 8 animals. Testicular torsion was created by rotating the left testis 720° in a clockwise direction. The ischemia period was 5 h and orchiectomy was performed after 5 h of detorsion. EGb 761 (50 mg/kg, orally) was administrated only once, 40 min prior to detorsion. To date, no more histopathological changes on testicular torsion/detorsion induced ischemia-reperfusion (I/R) injury in rats by EGb 761 treatment have been reported. Spermatogenesis and mean seminiferous tubule diameter (MSTD) were significantly decreased in I/R groups were compared to the control group. Furthermore, EGb 761 treated animals showed an improved histological appearance in I/R group. Our data indicate a significant reduction in the activity of TUNEL and endothelial nitric oxide synthase (eNOS) in testes tissue of I/R treated with EGb 761 therapy. Electron microscopy of the testes of rats demonstrated that EGb 761 pretreatment was particularly effective in preventing the mitochondrial degeneration, dilatation of SER and enlarged intercellular spaces in both Sertoli and spermatid cells in I/R treated animals. We believe that further preclinical research into the utility of EGb 761 may indicate its usefulness as a potential treatment on testes injury after I/R in rats.     

Effect of long‐term vasectomy on seminiferous tubules in the guinea pig

The little previous work on the influence of vasectomy on the guinea pig testis has given controversial results. One group reports that the guinea pig suffers autoimmune orchitis while others claim damage may be mechanical. To clarify the issue, this study compares the morphology of seminiferous tubules 3 years after left unilateral vasectomy (8 guinea pigs) and control sham operation (6 animals). Grossly, left and right testes following left‐sided vasectomy were similar to controls and not significantly different in weight. On histology, left and right experimental testes and the control material showed various degrees of seminiferous tubular degeneration, including intraepithelial vesicle formation, loss of germ cells and intraluminal macrophages. Although vesicle formation was striking in most testes, quantitative analysis indicated that it was more frequent in the ipsilateral testis following unilateral vasectomy. It seems that vasectomy had exacerbated an age‐related phenomenon. Lymphocytic infiltration was seen in five of the left testes following vasectomy, in two of the corresponding right testes, but in none of the controls. Two vasectomized left testes, however, showed atrophic changes but no lymphocytic invasion. The results suggest that autoimmune orchitis follows vasectomy but that it may not be the primary cause of degeneration. Attempts to gain positive evidence for mechanical damage, however, were inconclusive. Clin. Anat. 12:250–263, 1999. © 1999 Wiley‐Liss, Inc.     

激光多普勒流量计观察单侧输尿管梗阻大鼠双侧肾皮质微循环血流变化

目的:用激光多普勒流量计观察单侧输尿管梗阻大鼠双侧肾皮质微循环血流的变化,探讨梗阻侧肾间质纤维化的发病机制及健侧肾的代偿机制。方法:成年雌性SD大鼠,随机分为假手术组和模型组。假手术组仅将输尿管游离但不结扎离断,模型组行单侧输尿管结扎术。术后第7、14和21天随机选取并处死各组中的6只大鼠,观察双肾病理学改变,并检测双侧肾皮质微循环血流。结果:H-E染色显示假手术组双侧肾各时间点肾单位结构正常,间质无增宽;模型组大鼠梗阻侧肾术后7 d出现早期间质纤维化的病理改变,并随梗阻时间延长逐渐加重;健侧肾小球系膜细胞增生并随代偿时间延长逐渐增多。肾皮质微循环血流,与假手术组比较,模型组大鼠健侧肾皮质微循环血流显著增加,梗阻侧肾皮质微循环灌注量先增加后进行性降低。结论:血液流变学改变、梗阻侧肾皮质微循环血流灌注量进行性减少是肾间质纤维化的发病机制之一;而健侧肾皮质微循环血流灌注量增高,在一定程度上有利于健侧肾的功能代偿。     

Sympathectomy decreases size and invasiveness of tongue cancer in rats

The sympathetic nervous system plays a role in carcinogenesis wherein locally released sympathetic neurotransmitters affect proliferation, angiogenesis, vessel permeability, lymphocyte traffic and cytokine production. The present in vivo study was designed to investigate whether surgical sympathectomy, both unilateral and bilateral, had an effect on tumor growth, interstitial fluid pressure (IFP) and lymphatics in rat tongue cancer. We used 4-nitroquinoline-1-oxide (4-NQO) in drinking water for 19 weeks to induce tongue cancer in 20 Dark Agouti rats. After 11 weeks, one group underwent unilateral sympathectomy and another underwent bilateral sympathectomy, while the third group underwent sham surgery. By 19 weeks, tumors in the bilaterally sympathectomized (BL-SCGx) rats were significantly smaller (P<0.05), more diffuse in appearance and less invasive (P<0.05) compared with the large exophytic tumors in the sham-operated rats. The relative lymphatic area was significantly decreased (P<0.05) in tumors in the BL-SCGx rats compared with the sham group. Interestingly, the tumors in rats that underwent unilateral or bilateral sympathectomy had a significantly lower (P<0.05) IFP than those in sham rats. Lack of tyrosine hydroxylase (TH) immunoreactive nerves and few neuropeptide Y (NPY) positive fibers indicate absence of sympathetic nerve fibers in the bilateral sympathectomized group. The peritumoral lymph vessel area was correlated with the tumor size (P<0.001), depth of invasion (P<0.001), weight of rats (P<0.005) and IFP (P<0.05). In conclusion, the present study presents evidence that deprivation of sympathetic nerves decreases tumor growth in rat tongue, probably caused by decreasing IFP and lymph vessel area.     

输精管吻合术后不育原因的实验研究精子密度与睾丸功能

14只成年日本大耳白兔,双侧输精管结扎12月后,以显微外科技术行双侧输精管吻合术,3月后与雌兔配对交配,观察2个月,根据妊娠与否分为输精管吻合育组(VFG)和输精管吻合不育组(VIG),各7只。另设输精管结扎组(VG)和假手术组(SOG)作为对照。结果表明,(1)VFG的精子密度与SOG比较虽为低值(P<0.01),但显著地高于VIG(P<0.01)。(2)精子密度与睾丸ACE活力、Na~+,K~+-ATPasc活力、Mg~(++)-ATPasc活力、睾丸cAMP含量均呈显著的正相关。(3)精子密度、cAMP含量与ABP呈明显的负相关。(4)VFG血清睾酮含量与VIG比较有显著差异(P<0.05)。VFG、VIG中血清睾酮水平与精子密度呈明显的正相关(r=0.60、P<0.05)。     

The influence of vasovasostomy on testicular alterations after vasectomy in Lewis rats

The occurrence of alterations in testicular weight and morphology after vasectomy and vasectomy reversal by vasovasostomy was studied in Lewis rats. Animals were studied 3, 4, and 7 months after bilateral vasectomy or a vasectomy followed 3 months later by vasovasostomy. Other rats served as sham-operated controls. The weights of the testes in vasectomy and vasovasostomy animals fell into two groups-small testes weighing less than 0.88 g and normal-sized testes of 1.2 g or more. When the extent of testicular alterations was estimated in sections for light microscopy by use of a semiquantitative testicular biopsy score count (TBSC), the morphology of the testes corresponded closely to the testis weight (r = .94), small testes having correspondingly low TBSC scores. In severely altered small testes, the seminiferous tubules were narrower than in sham-operated rats, and numbers of germ cells were greatly depleted. Many tubules contained only Sertoli cells and spermatogonia, although spermatocytes were present in a minority of tubules. A few seminiferous tubules contained multinucleate spermatids. Electron microscopy of severely altered tubules revealed closely apposed processes of Sertoli cells, which contained filaments, microtubules, and endoplasmic reticulum. In contrast, testes with normal weight in vasectomy and vasovasostomy groups resembled those of the sham-operated animals. Comparison of distributions of testicular biopsy score counts demonstrated differences between vasectomy and vasovasostomy groups as time after operation increased. At the 3-4-month intervals, approximately one-third of the testes were severely altered in both vasectomy and vasovasostomy groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Degenerated tubules in the guinea pig testis after long-term vasectomy or sham operation

The testes of eight unilaterally vasectomized and six sham-operated Dunkin Hartley guinea pigs were examined 3 years after operation by wax and resin histology and transmission electron microscopy. Degenerated tubules are reported that were common on the side of vasectomy but also found in the contralateral testes and in the controls. A central accumulation of macrophages, rich in phagocytosed debris including spermatozoal fragments, was surrounded by attenuated Sertoli cells, a markedly thickened basement membrane and myoid cells. At some sites macrophages impinged directly on the basement membrane. They probably represented highly degenerated seminiferous tubules. The study suggests that the response to injury of seminiferous tubules may show species variations. Macrophages did not feature in the degenerated seminiferous tubules we reported following vasectomy in the rat. However, the rat showed striking changes in the morphology of the basal laminae and myoid cells which did not occur in the guinea pig. Pathological changes have been reported in the human testis following vasectomy but their etiology is unclear. Studies in the guinea pig are enhancing understanding of the mechanisms and features of testicular damage.     

Pathological and Immunological Effects of Surgically Induced Varicocele in Juvenile and Adult Rats

ABSTRACT: The presence of a varicocele in adult men has been correlated with infertility. This study documents the effect of an experimentally induced unilateral varicocele in 21-day-old juvenile prepubertal and 51-day-old adult rats (n=10 per group) on subsequent adult testicular function. Varicoceles were induced by partial occlusion of the spermatic vein. There were ten sham-operated and five nonoperated control rats in each age group. The rats were sacrificed 1 month after surgery. Intrascrotal temperatures were elevated in both groups with varicoceles. Histologically, the ipsilateral testes of rats in both age groups demonstrated a decrease in the numbers of functioning seminiferous tubules and germ cells, but the decrease was significantly greater in the juveniles than in the adult rats. No changes were seen in the contralateral testes. Significant titers of cytotoxic sperm antibodies were present in all animals with varicoceles, which is in contrast to controls. The juveniles had significantly lower antibody titers (mean log ± SEM; 3.2 ± 0.09 vs. 8.5 ± 1.1, P < 0.001) than the adults. The induction of a unilateral varicocele damaged spermatogenesis and testicular function to a greater extent in juveniles than in adult rats. This damage may be immune complex-mediated.     

Reinnervation of Müller's smooth muscle by atypical sympathetic pathways following neonatal ganglionectomy in the rat: structural and functional investigations of enhanced neuroplasticity

Müller's extraocular smooth muscle is reinnervated by sympathetic nerves following denervation by ipsilateral superior cervical ganglionectomy in neonates but not in older animals. Experiments were performed to determine: (1) the source and extent of reinnervation, (2) the role of impulse activity in sympathetic outgrowth and (3) the effects of reinnervation on smooth muscle maturation. Müller's muscles were evaluated structurally (muscle volume, catecholamine histochemistry, retrograde labeling of sympathetic neurons) and functionally (contractile responses to electrical stimulation of postganglionic innervation and adrenoceptor agonist) in control preparations and in muscles following neonatal ipsilateral superior ganglionectomy, ipsilateral decentralization, ipsilateral superior ganglionectomy combined with contralateral decentralization of chemical (guanethidine) sympathectomy. Fluorescent tracer injections of muscles in adult control rats labeled cells in the ipsilateral superior (98%) and middle cervical ganglia. Acute ipsilateral superior ganglionectomy produced complete degeneration of sympathetic innervation of Müller's muscle in neonatal and adult rats. In preparations denervated neonatally and maintained chronically, muscles were reinnervated by neurons in both the contralateral superior and ipsilateral middle cervical ganglia. The total number of neurons reinnervating the muscle was one half that of controls. Sectional density of innervation was 45% of control. Electrical stimulation of postganglionic axons in the contralateral pathway produced muscle contractions with a prolonged time course. Reinnervation alleviated, in part, deficits in muscle volume and contraction which occurred following sustained denervation by chemical sympathectomy. Decentralization decreased ipsilateral muscle volume but did not affect numbers of neurons projecting to or nerve density within the muscle. Stimulation frequencies required to produce a 50% maximum contraction were reduced in these preparations. Decentralization of the contralateral ganglion did not impede sprouting into the denervated muscle, as nerve density and number of labeled cells were comparable to muscles reinnervated by contralateral ganglia with intact preganglionic innervation. However, maximum contraction to electrical stimulation was reduced. Comparisons with ipsilaterally decentralized muscles revealed that increased stimulation frequencies were required for 50% maximum contraction.(ABSTRACT TRUNCATED AT 400 WORDS)     

The fate of sperm after vasectomy in the hamster

Young adult male hamsters were subjected to bilateral vasectomy. The reproductive tracts were studied by light and electron microscopy at intervals up to 1 year after the operation. Sperm continued to be produced, since testicular alterations were focal. Spermatic granulomas were associated with the excurrent ducts of all animals 5 months or 1 year after vasectomy and with those of one of four hamsters 2 weeks after the operation. Phagocytosis of sperm in the lumina of the efferent ducts and proximal parts of the epididymis, and disintegration of membranous components of intraluminal sperm occurred in approximately three-fourths of the animals studied 5 months or more after vasectomy. The results indicate that after vasectomy in the hamster sperm are disposed of by phagocytosis in spermatic granulomas, intraluminal phagocytosis, and dissolution in the lumen of the male ducts, although the latter process may be incomplete.     

Contralateral decrease of neostriatal dopamine concentration after unilateral pallidal lesion in the rat.

Seven days after unilateral electrolytical and chemical (6-hydroxydopamine (6-OHDA)) lesions in the globus pallidus ipsi- and contralateral neostrial dopamine (DA) concentrations were measured in rats. A definite contralateral DA-decrease was demonstrable, the extent of which was in correlation with ipsilateral decrease.     

血必净通过激活PI3K/Akt/mTOR信号通路减轻大鼠睾丸缺血再灌注损伤

目的:探究血必净对缺血再灌注(I/R)损伤大鼠睾丸的保护作用及其相关机制。方法:45只雄性SD大鼠随机分为对照组、模型组、血必净低剂量组、血必净高剂量组和地塞米松组(均n=9);除对照组大鼠外,其它各组大鼠构建睾丸扭转复位模型,术后低、高剂量组及地塞米松组大鼠分别腹腔注射0.5和2 mL·kg^-1·d^-1血必净及0.5 mL·kg^-1·d^-1地塞米松。用药第3、7和14天取各组大鼠左侧睾丸,采用HE染色观察各组大鼠睾丸组织病理学改变;生化检测各组大鼠睾丸组织中丙二醛(MDA)、超氧化物歧化酶(SOD)、内皮素1(ET-1)和一氧化氮(NO)水平,Western blot检测各组大鼠睾丸组织中细胞周期相关蛋白、细胞凋亡相关蛋白以及PI3K/Akt/mTOR信号通路相关蛋白的水平。结果:血必净可显著减轻I/R大鼠睾丸损伤,显著升高I/R大鼠睾丸组织中SOD活性,降低MDA、ET-1和NO的含量,抑制I/R损伤组织中的氧化应激,介导细胞周期和细胞凋亡相关因子的表达,并显著升高I/R大鼠睾丸中p-PI3K、p-AKT、p-mTOR和p-S6K的蛋白水平,其作用效果具有时间依赖性和剂量依赖性。结论:血必净通过介导细胞周期和细胞凋亡相关蛋白的表达,抑制氧化应激反应,激活PI3K/Akt/mTOR信号通路来减轻大鼠睾丸I/R损伤,且其作用效果呈剂量依赖性和时间依赖性。     

Anatomical plasticity of the tectospinal tract after unilateral lesion of the superior colliculus in the neonatal rat

Summary After unilateral ablation of the superior colliculus (SC) in neonatal or adult rats, the reorganization of the tectospinal tract (TST) was examined using the technique of anterograde transport of horseradish peroxidase to which wheat germ agglutinin had been conjugated (WGA-HRP). In neonatally lesioned rats, aberrant labeled terminals of TST axons were found on the ipsilateral side of the spinal cord. Postnatal development of the TST was then studied by retrograde transport of HRP to determine whether the aberrant tectospinal projections resulted from normally transient ipsilateral projections that persisted in operated rats or were due to collateral sprouting of projections to the contralateral projection field. The results failed to show an ipsilateral projection from the SC to spinal cord in normal neonatal rats. However, in neonatally lesioned rats, aberrant labeled fibers were observed recrossing the midline of the cervical spinal cord. Therefore, the increase in labeled terminals on the ipsilateral side following unilateral SC ablation appeared to originate from collateral sprouting at the spinal cord level of TST fibers from the intact pathway.     

大鼠睾丸与腹腔Mφ的IL－1样物质活性及输精管结扎对其影响

雄性Ｗｉｓｔａｒ大鼠２１只，分为输精管结扎组（ＶＧ）和假手术组（ＳＯＧ）。术后４个月，以胸腺细胞增殖法检测腹腔Ｍφ和睾丸组织匀浆上清中ＩＬ－１样物质的活性。结果表明，（１）ＩＬ－１物质活性，随睾丸匀浆上清稀释倍数增加而增高，而不同稀释倍数的腹腔Ｍφ培养上清的各测定值均于同一水平。（２）输精管结扎对腹腔Ｍφ培养上清的ＩＬ－１样物质活性无影响，但明显地提高了睾丸匀浆上清的ＩＬ－１样物质活性。本实验结果提示，睾丸组织中存在有ＩＬ－１样物质的抑制因子。     

Protective effects of melatonin on testicular torsion/detorsion-induced ischemia–reperfusion injury in rats

Testicular torsion causes an enhanced formation of reactive oxygen species, which contributes to the pathophysiology of tissue damage. The aim of this study was to investigate the protective effect of melatonin on testicular torsion/detorsion-induced ischemia–reperfusion (I/R) injury. A total of 24 male Wistar albino rats were divided into three groups of 8 animals each: control, I/R, and I/R treated with melatonin. The ischemia period was 5 h and orchiectomy was performed after 5 h of detorsion. Melatonin (10 mg/kg, intraperitoneally [i.p.]) was administrated only once, 40 min prior to detorsion. Spermatogenesis and mean seminiferous tubule diameter (MSTD) were significantly decreased in the I/R groups were compared to the control group. Furthermore, the melatonin treated animals showed an improved histological appearance in the I/R group. Our data indicate a significant reduction in the activity of TUNEL; there was a rise in the expression of proliferating cell nuclear antigen (PCNA) and testosterone in testes tissue of the I/R group treated with melatonin therapy. Electron microscopy of the testes of the rats demonstrated that pretreatment with melatonin was particularly effective in preventing mitochondrial degeneration, dilatation of SER, and enlarged intercellular spaces in both Sertoli and spermatid cells in the I/R treated animals. We believe that further preclinical research into the utility of melatonin may indicate its usefulness as a potential treatment on testes injury after I/R in rats.