IMMUNOHISTOCHEMICAL,HISTOLOGICAL AND ULTRASTRUCTURAL EVALUATION OF THE EFFECTS OF LEPTIN ON TESTES IN MICE

This study was undertaken to examine the effects of leptin on testes in mice. For this purpose, 12 male mice were divided into two groups. Animals in Group I were designated as control. Mice in Group II were injected daily with leptin for 5 days. All animals were decapitated at the end of the experiment. The testes were removed and weighed out. Testicular tissue specimens were processed for light and electron microscopic examination and semi-quantitative evaluation of immunohistochemical testosterone staining. Intensity of immunostaining was determined on a scale between 0 (no staining) and 5 (heavy staining). For morphometric comparison, diameters of seminiferous tubules from each group were measured. In the leptin injected group, testicular weights and diameters of seminiferous tubules were significantly increased in comparison to control values. In light microscopic examination, an increase in secretory granules in the cytoplasm of Leydig cells was observed after leptin treatment. In the same group, distinct changes indicative of increased cell activation were seen in the ultrastructure of Leydig cells. Amount of mitochondria, lysosomes and cytoplasmic secretory granules were increased. Furthermore, an increase in extensiveness of rough endoplasmic reticulum was noted in this group. Immunohistochemical testosterone staining of the cytoplasm of Leydig cells was heavy (5 +) in the leptin treated mice compared to mild score (2 +) in the control mice. Additionally, heavy immunostaining of testosterone was also observed in the interstitial space after injection of leptin. The present findings indicate that testicular functions and synthesis of testosterone increase after administration of leptin.     

Effect of formaldehyde inhalation on Hsp70 in seminiferous tubules of rat testes: an immunohistochemical study

One parameter which might provide an insight into the underlying mechanism of the effect of formaldehyde (FA) inhalation on testicular tissue, is the assessment of heat shock protein 70 (Hsp70), which increases promptly in cells exposed to stress caused by chemical toxicity. Thus, following subchronic exposure at cytotoxic concentrations, we studied the immunohistochemical effect of FA inhalation on changes in Hsp70 content in testicular tissue. We used 18 albino Wistar rats divided into three groups, exposed to 0 (control), 5 and 10 ppm FA gas for a total of 91 days, 8 h/day, five days a week. Serum testosterone levels were determined using a chemiluminescent enzyme immunoassay. Testicular tissues were stained with Hematoxylin-Eosine and Hsp70 immunohistochemically performed. Diameters of seminiferous tubules and serum testosterone levels in animals inhaling FA were significantly decreased. In seminiferous epithelium stained for Hsp70, compared to those in the control group, the spermatogenetic cells in the experimental groups demonstrated an obvious increase in immunoreaction spermatides in the adluminal region and especially in the cytoplasm of spermatocytes. Immunoreaction of Hsp70 was detected in the spermatogonias of animals exposed to FA inhalation as opposed to those of the control group. Compared to the control, there was a significant increase in the immunoreactions observed not only in the cytoplasm of primary spermatocytes, but also spermatides in the adluminal region of the seminiferous tubules. In conclusion, FA gas may damage spermatogenetic cells and increase Hsp70 synthesis.     

氯氰菊酯暴露对青春期雄性小鼠精子发生的影响

[目的]探讨氯氰菊酯暴露对青春期雄性小鼠精子发生的影响及其可能机制。[方法]选择30只5周龄雄性ICR小鼠,随机分为暴露组和对照组,于出生后35天（PND35）至PND70,每天给予暴露组小鼠氯氰菊酯（25mg/kg）灌胃染毒,对照组以等容积的玉米油灌胃。末次染毒16h后,处死小鼠,取附睾尾评价精子数量;取睾丸称重并进行组织病理学检查;免疫组织化学法检测睾丸间质细胞;放射免疫分析法检测血清和睾丸组织睾酮水平;蛋白质免疫印迹法测定睾丸组织类固醇激素合成急性调节蛋白（StAR）和睾酮合成关键酶蛋白表达水平。[结果]暴露组小鼠睾丸生精小管管腔内出现大空泡。与对照组相比,暴露组第Ⅶ-Ⅷ期生精小管所占百分比明显下降,附睾尾精子数量明显减少,血清和睾丸组织睾酮含量明显降低,睾丸组织生成StAR的表达明显下调,而氯氰菊酯对小鼠睾丸间质细胞数量无影响。[结论]青春期氯氰菊酯暴露后对小鼠精子发生有损害作用,这可能与睾丸睾酮合成的降低有关。     

Effect of vinyl chloride on testis in rats

A total of 300 male adult Wistar rats (180-220 g) were used. Animals were divided into four groups: control, vinyl chloride (VC) 10-, 100-, and 3000-ppm exposed groups. Seventy-five rats were used for each group. Inhalation exposure to VC was conducted 6 hr per day and 6 days per week. In the third, sixth, and twelfth month following exposure 8-30 rats of each group were killed. The others were under observation and sacrificed after 18 months. After exposure to VC, the organ and body weight ratio, such as the kidney, liver, spleen, and heart were increased, but those of the testis were decreased in the experimental groups in the sixth month. The differences between experimental groups and the control group were statistically significant (P less than 0.05 or P less than 0.01). The weights of testis were decreased and damage of testicular seminiferous tubules were found in rats by histopathological examination. Incidence of damage of testicular seminiferous tubules in the control, 10-, 100-, and 3000-ppm groups were 18.9, 29.7, 36.5, and 56.0%, respectively. There was an obvious dose-response relation between the concentration of VC and the incidence of testis damage, with a correlation coefficient of 0.993 (P less than 0.01). Statistically, the incidence of damage of testicular seminiferous tubules in rats in the 3000-ppm group and in 100-ppm group were significantly higher than that of the control group, respectively (P less than 0.001) and P less than 0.05).     

The Effects of Endosulfan on the Testes of Bluegill Fish, Lepomis macrochirus: A Histopathological Study

The effect of endosulfan, an Organochlorine pesticide, on bluegill testes was studied. Endosulfan is aqua-toxic and has an immediate effect on fish and other aquatic life. In this experiment, we exposed the fish for 24-, 48-, 72-, 96-h, and 1- and 2-week periods. A second group of fish without exposure to endosulfan served as the control. The control testis appeared structurally normal. The seminiferous tubules were of round or oval shape and contained primary spermatogonia, primary spermatocytes, secondary spermatocytes, spermatozoa, spermatids, Sertoli cells, and interstitial cells of Leydig. Within the connective tissue that connected the seminiferous tubules were Leydig cells. After 24 h of exposure, there was evidence of slight signs of connective tissue splintering. The 48-h exposure resulted in breakage of primary spermatocyte walls and separation from the seminiferous tubules. The 72-h testis showed further connective tissue damage and migration of primary spermatogonia into the lumen. After 96 h, there was significant damage to connective tissue and the seminiferous tubules were less pronounced. After 1 and 2 weeks, the seminiferous tubule walls were disrupted and missing in places and the structure of the testis was very disorganized compared to the control testis. Biometric analysis indicated that the diameter of the primary spermatogonia decreased from 24 h to two weeks. There also appeared to be fewer Leydig cells, responsible for testosterone production, over the exposure period and damaged Sertoli cells, which support, protect, and nourish the spermatogonic cells, synthesize ABP, and assist in maintaining the necessary concentration of testosterone in the seminiferous tubules so that spermatogenesis can progress. These kinds of damage could affect the spermatids and spermatozoa and possibly have a negative impact on spermatogenesis and male fertility, affecting bluegill fish population.     

邻苯二甲酸二丁酯对F1代雄性斑马鱼性腺发育影响的研究

目的探讨邻苯二甲酸二丁酯(DBP)对F1代雄性斑马鱼性腺发育的影响。方法将48对成年斑马鱼随机分为4组:空白对照组、丙酮溶剂对照组、1250μg/LDBP高剂量组和625μg/LDBP低剂量组。每组12对、设两个鱼缸。连续暴露于DBP30天后,将各组的雌雄鱼交配,孵化出的F1代斑马鱼在清水中饲养至180dph。各组随机选择20条F1代雄性斑马鱼,行性腺指数(GSI)分析以及精巢组织病理学检查。结果与对照组相比,DBP高剂量组F1代雄鱼的GSI值为5.23%±1.5%,明显低于空白对照组(6.09%±2.5%)或溶剂对照组(6.08%±1.2%)(P<0.05)。精巢组织学检查表明,成年斑马鱼DBP暴露明显抑制F1代雄鱼的性腺发育,引起生精小管畸形,且精巢间质(Leydig)细胞广泛而明显的增生与精子数量减少同时存在的特征十分明确。结论出生前暴露于DBP可使F1代斑马鱼成年后的精巢发育受到不同程度的抑制,生精小管畸形,精子数量减少及Leydig细胞大量增生同时存在于精巢中。DBP在雄性斑马鱼体内的这种抗雌激素活性与它引发雄性大鼠、狨猴和人类的睾丸反应相类似。     

Effect of (D-Trp6, Pro9-NEt)-GnRH on the function and ultrastructure of pituitary and testis in male rats

Groups of ten adult male Wistar rats were treated chronically with GnRH agonist for different durations. The responses of pituitary and testis to GnRH agonist were evaluated by serum and testicular testosterone, serum and pituitary LH, and testicular LH receptors. Testicular testosterone and LH receptors were decreased very significantly under our experimental regimen, irrespective of the duration of the treatment Serum testosterone levels were reduced after 10 and 15 injections, but only rats receiving 10 injections showed a significant increase in serum LH levels and decrease of pituitary LH content. The type II gonadotropes of the pars distalis of pituitary were increased in number but showed a higher degree of dilated smooth endoplasmic reticulum with few secretory granules. Many large lipid droplets appeared in the cytoplasms of the Leydig cells. Degenerative changes were observed in most seminiferous tubules following GnRH agonist treatment. Obvious abnormal acrosome and nuclear caps of some spermatids were also observed. The functional changes caused by GnRH agonist coincided with their ultrastructural appearance.     

EFFECT OF CHRONIC LOW DOSE OF METHOTREXATE ON CELLULAR PROLIFERATION DURING SPERMATOGENESIS IN RATS

This study was conducted to evaluate cellular proliferation of germinal and non-germinal elements of seminiferous tubules following continuous Day 1 to Day 17 exposure of methotrexate (12.5 microgram) in male rats. There was significant decrease in the diameter of seminiferous tubules (P?<?0.10) followed by increase of interstitial space (P?<?0.01). The size of various stages of primary, secondary spermatocytes, and spermatids was altered significantly compared to controls. Vacuolization/decondensation of “chromatin-mass” in spermatocytes changed from rounded to oval. The size of the Sertoli and Leydig cells were reduced significantly. Basement membrane at some places seems to be disrupted and thin in experimental testis. Methotrexate induced cytotoxicity on the proliferation of cellular contents of seminiferous tubules elucidating the mechanism of dose-dependent drug induced testicular damage during spermatogenesis.     

Hormones: what the testis really sees

Various barriers in the testis may prevent hormones from readily reaching the cells they are supposed to stimulate, especially the hydrophilic hormones from the pituitary. For example, LH must pass through or between the endothelial cells lining the blood vessels to reach the surface of the Leydig cells, and FSH has the additional barrier of the peritubular myoid cells before it reaches the Sertoli cells. The specialised junctions between pairs of Sertoli cells would severely restrict the passage of peptides from blood to the luminal fluid and therefore to the cells inside this barrier, such as the later spermatocytes and spermatids. There is evidence in the literature that radioactively labelled LH does not pass readily into the testis from the blood, and the concentration of native LH in the interstitial extracellular fluid surrounding the Leydig cells in rats is only about one-fifth of that in blood plasma. Furthermore, after injection with LHRH, there are large rises in LH in the blood within 15 min, at which time the Leydig cells have already responded by increasing their content of testosterone, but with no significant change in the concentration of LH in the interstitial extracellular fluid. Either the Leydig cells respond to very small changes in LH, or the testicular endothelial cells in some way mediate the response of the Leydig cells to LH, for which there is now some evidence from co-cultures of endothelial and Leydig cells. The lipophilic steroid hormones, such as testosterone, which are produced by the Leydig cells, have actions within the seminiferous tubules in the testis but also in other parts of the body. They should pass more readily through cells than the hydrophilic peptides; however, the concentration of testosterone in the fluid inside the seminiferous tubules is less than in the interstitial extracellular fluid in the testis, especially after stimulation by LH released after injection of LHRH and despite the presence inside the tubules of high concentrations of an androgen-binding protein. The concentration of testosterone in testicular venous blood does not rise to the same extent as that in the interstitial extracellular fluid, suggesting that there may also be some restriction to movement of the steroid across the endothelium. There is a very poor correlation between the concentrations of testosterone in fluids from the various compartments of the testis and in peripheral blood plasma. Determination of the testosterone concentration in the whole testis is also probably of little predictive value, because the high concentrations of lipid in the Leydig cells would tend to concentrate testosterone there, and hormones inside these cells are unlikely to have any direct effect on other cells in the testis. The best predictor of testosterone concentrations around cells in the testis is the level of testosterone in testicular venous blood, the collection of which for testosterone analysis is a reasonably simple procedure in experimental animals and should be substituted for tissue sampling. There seems to be no simple way of determining the concentrations of peptide hormones in the vicinity of the testicular cells.     

不同发育阶段大鼠睾丸中Calretinin的表达

目的：Calretinin（CALB2）是一种钙结合蛋白。前期研究表明,CALB2可表达于人睾丸组织,推测其参与睾丸功能的调节。本研究观察不同发育阶段大鼠睾丸中CALB2的表达水平,探讨其在调节雄激素生成中的作用。方法： 3～4周龄SD雄性大鼠作为性发育前组（相当于人类的青春期前,n=35）,16周龄SD鼠作为性成熟组（相当于人类的成年期,n=16）,12个月以上的作为老年组（相当于人类男子的中老年,n=10）。放射免疫法测定各组血清睾酮浓度;免疫组织化学法观察CALB2的定位表达;定量聚合酶链反应（qPCR）和蛋白质印迹法（Western Blot）分别检测睾丸中CALB2 mRNA和蛋白水平的表达。结果：CALB2表达定位于睾丸的间质细胞,细胞内定位于细胞质中。性发育前组大鼠血清睾酮水平最低,性成熟组最高,差异有统计学意义（P＜0.05）。性成熟组大鼠睾丸CALB2的表达水平较性发育前组和老年组均升高（P＜0.05）。结论：睾丸组织中,CALB2表达于间质细胞的细胞质;在不同发育阶段,睾丸间质细胞CALB2表达水平与血清睾酮水平呈正相关,表明CALB2参与调节雄激素生成。     

Effect of Sexual Maturity on Testicular Injury Subsequent to Procarbazine Administration in Rats

The present study examined the effect of age on various aspects of Leydig cell and Sertoli cell function in Sprague-Dawley rats administered procarbazine. Procarbazine was administered intraperitoneally to Sprague-Dawley rats aged 14, 24, and 60 days in 3 weekly injections of 200 mg/kg. Animals were sacrificed 1 week after the last injection. Severe impairment of spermatogenesis was evident in all animals. Sertoli cell function, as assessed by total testicular ABP content, was not significantly different between procarbazine-treated animals and controls in any age group. On the other hand, procarbazine administration resulted in a 60% reduction in total intratesticular testosterone content in the 14-day-old rats but not in the 24- or 60-day-old animals. Serum testosterone was significantly reduced by 50% in the group of 14-day-old animals but not in the other age groups. Serum LH values were not significantly changed from control levels in any age group. Testicular content of Fe, Zn, Mn, and Cn were unaltered by procarbazine administration in any age group. Since serum LH and testicular cation content were not affected by procarbazine treatment, the significant decreases in serum and testicular testosterone in 14-day-old animals after procarbazine administration may indicate a direct age-dependent effect of procarbazine on Leydig cell function.     

Testis functions and sexual potentia in langur monkey treated with a combination steroidal contraceptive formulation

Administration of a combination formulation of danazol (100 mg/day; oral) plus testosterone enanthate (TE) (50 mg/15 days; i.m.) for 30 to 60 days in adult male langur monkeys resulted in the reversible suppression of testicular function without affecting the sexual potentia. Testicular weight and volume decreased significantly along with the mass atrophy of germinal epithelium and impaired morphology of Leydig and Sertoli cells. A conspicuous shrinkage of seminiferous tubules, Leydig cell nuclei and Sertoli cell nuclei was noted. Elevation of testicular cholesterol, total lipids, glycogen and phosphatases activity with the depletion of total proteins, nucleic acid, sialic acid and fructose was noteworthy. All changes were maintained during maintenance dose studies (danazol: 50 mg/day; oral plus TE: 50 mg/15 days; i.m.) for 60 days. Resumption of all measures to normal was evident following 120 days of recovery. It can be concluded that the exogenous TE substitutes the serum testosterone levels to maintain extratesticular androgen actions even after interference by danazol of Leydig cell function along with spermatogenesis inhibition.     

Evaluation of the toxic potentials of cypermethrin pesticide on some reproductive and fertility parameters in the male rats

Adult male Sprague-Dawley rats were exposed to tap water containing 0, 8,571, 17,143, or 34,286 ppm cypermethrin for 12 weeks. Based on water consumption per animal per day the rats received 13.15, 18.93, and 39.66 mg cypermethrin, respectively. Fertility was significantly reduced in male rats ingesting cypermethrin at a concentration of 13.15 and 18.93 mg in that the number of females impregnated by them was significantly reduced. The number of implantation sites was significantly reduced in females mated with males that had ingested cypermethrin at a concentration of 39.66 mg. A significant reduction in the number of viable fetuses was observed in females impregnated by the exposed males at all three doses of cypermethrin. The body weight gain was significantly lower in the treated males. Ingestion of cypermethrin at a concentration of 18.93 or 39.66 mg per day resulted in a significant increase in the weights of testes and seminal vesicles. Preputial gland weights were increased at all three concentrations of cypermethrin. Epididymal and testicular sperm counts as well as daily sperm production were significantly decreased in exposed males. The serum levels of testosterone, follicle-stimulating hormone and luteinizing hormone were significantly reduced in males exposed to 39.66 mg per day. Ingestion of cypermethrin at 18.93 and 39.66 mg/animal/day also resulted in a significant decrease in the perimeter and number of cell layers of the seminiferous tubules. The testes of treated animals were infiltrated with congested blood vessels with marked hemorrhage and a significant accumulation of connective tissue surrounding the seminiferous tubules, which contained a large number of immature spermatids. These results clearly demonstrate the adverse effects of cypermethrin pesticide on fertility and reproduction in male rats. Received: 1 January 2001/Accepted: 28 May 2001     

Relative and combined effects of ethanol and protein deficiency on gonadal function and histology

The aim of the present study is to analyse the relative and combined effects of ethanol and protein deficiency on serum testosterone and LH, and on gonadal histology, in ethanol fed rats. The study was performed in 32 animals divided into four groups, fed with the Lieber & DeCarli control, 36% ethanol, 2% protein, and 36% ethanol 2% protein containing diets, respectively. Two months later, rats were anaesthetized with pentobarbital and sacrificed, and the right testes and epididymus were carefully removed. Both ethanol and protein deficiency independently lead to a decrease in serum testosterone levels, and to testicular atrophy, lowest testosterone levels and highest degrees of atrophy being observed in the rats receiving the 36% ethanol, 2% protein containing diet. Both serum testosterone and testicular size and weight significantly correlated with final weight and serum albumin. Hypospermia, atrophy of the seminiferous tubules, and reduced epididymal diameter were also observed in this last group of animals. Thus, protein deficiency may contribute to hypogonadism of alcoholics.     

Assessment of the potential reproductive toxicity of long-term exposure of adult male rats to low-dose formaldehyde

Formaldehyde (FA), a ubiquitous environmental pollutant, is extensively used in hospitals, laboratories and many industrial settings. Previous studies have showed that short-term, high-dose FA exposure is toxic to male reproduction of mammals. In this paper, we evaluated the male reproductive toxicity of long-term, low-dose formaldehyde exposure in rats, and explored the potential mechanisms. A total of 30 Sprague-Dawley male rats were randomly allotted to three groups, rats were exposed to FA at a dose of 0 (control), 0.5, 2.46 mg/m3 respectively by inhalation for consecutive 60 days. The results indicated that the reproductive toxicity of FA is dose-dependent. Testicular, epididymal structure and function in rats of 0.5 mg/m3 FA exposure group showed no obvious difference compared with those in control group. However, sperm quantity and quality, testicular seminiferous tubular diameter, the activities of superoxide dismutase and glutathione peroxidase was significantly decreased whereas the level of malondialdehyde was significantly increased in rats of 2.46 mg/m3 FA exposure group compared with those in control group. Moreover, histopathological results showed atrophy of seminiferous tubules, decreases of spermatogenic cells and the lumina were oligozoospermic in testes of 2.46 mg/m3 FA exposure rats. In conclusion, the level of 0.5 mg/m3 can be considered as a safe level for FA exposure, but long-term FA exposure at a dose of 2.46 mg/m3 has a harmful effect on male reproduction by inducing oxidative stress in male rats.     

Ultrastructure of the Testis in Klinefelter's Syndrome

The ultrastructure of the testis in 5 cases of Klinefelter's syndrome was studied. In 3 cases there was complete hyalinization of the seminiferous tubules. In one case Sertoli cells were present, and in another case focal areas of spermatogenesis were seen in the tubules. Hyperplasia of the Leydig cells was found in every case. The Leydig cells had usually abundant smooth endoplasmic reticulum and lipofuscin pigment in the cytoplasm. This suggested that the function of the Leydig cells was normal. The Sertoli cells contained lipid droplets and glycogen-filled vacuoles in the cytoplasm.     

Reversibility of testicular atrophy induced by Di(2-ethylhexyl) phthalate in rats

Previous studies have shown that di(2-ethylhexyl) phthalate (DEHP) results in atrophy of testes and accessory sex organs accompanied by a decreased testicular concentration of zinc in rats. An experiment was performed to determine whether those changes in rat testes are reversible changes. Young Wistar male rats were administered 2.0 g/kg of DEHP for 14 days. At that time, one-half of the rats were killed for determination of zinc and testosterone concentrations in the testis, liver, and serum, and organ weights. The remaining rats were maintained for additional 45 days without further DEHP administration. Testicular weight of rats administered DEHP over the 14-day period was significantly less than that of the control animals, and testicular testosterone content and zinc concentrations were less than those of the control animals. At the end of the 45-day recovery phase, serum testosterone concentration returned to the control level, but testicular zinc concentration and testosterone content were still lower than those of the control animals. In addition, testicular weight of DEHP-treated rats was lower than that of the control animals and histologically, only a small number of seminiferous tubules showed spermatogenesis. These results indicate that, morphologically, DEHP-induced testicular atrophy appears to be of limited reversibility.     

Testicular apoptosis and histopathological changes induced by a 2.45 GHz electromagnetic field

There is a growing public concern about the potential human health hazard caused by exposure to electromagnetic radiation (EMR). The objective of this study is to investigate the effects of 2450 mhz electromagnetic field on apoptosis and histopathological changes on rat testis tissue. Twelve-week-old male Wistar Albino rats were used in this study. Eighteen rats equally divided into three different groups which were named group I, II and III. Cage control (group I), sham control (group II) and 2.45 GHz EMR (group III) groups were formed. Group III were exposed to 2.45 GHz EMR, at 3.21 W/kg specific absorption rate for 60 minutes/ day for 28 days. There was no difference among the groups for the diameter of the seminiferous tubules, pyknotic, karyolectic and karyotic cells. However, the number of Leydig cells of testis tissue of the rats in group III was significantly reduced comparing with the group I (p < 0.05). Estimation of spermatogenesis using the Johnsen testicular biopsy score revealed that the difference between groups is statistically significant. The level of TNF-α, Caspase-3 and Bcl-2 were compared, and no significant difference was found between the groups. When Bax apoptosis genes and Caspase-8 apoptosis enzyme were compared, there were significant differences between the groups (p < 0.05). Electromagnetic field affects spermatogenesis and causes to apoptosis due to the heat and other stress-related events in testis tissue.     

Effects of benzo(a)pyrene on intra-testicular function in F-344 rats

The objective of this study was to evaluate the reproductive risk associated with exposure of adult male Fisher-344 (F-344) rats to inhaled benzo(a)pyrene (BaP), a ubiquitous environmental toxicant present in cigarette smoke, automobile exhaust fumes and industrial emissions. Rats were assigned randomly to a treatment or control group. Treatment consisted of exposure of rats via nose-only inhalation to 75 microg BaP/m3, 4 hours daily for 60 days, while control animals were unexposed (UNC). Blood samples were collected immediately on day 60 of exposures (time 0) and subsequently at 24, 48, and 72 hours, to assess the effect of exposures to BaP on plasma testosterone and luteinizing hormone (LH) concentrations. Mean testis weight, total weight of tubules and total tubular length per paired testes were reduced 33% (P < 0.025), 27% (P < 0.01) and 39%, respectively in exposed rats (P < 0.01) compared with UNC rats. The number of homogenization -resistant spermatids was significantly reduced in BaP-exposed versus UNC rats. Plasma testosterone and intra-testicular testosterone (ITT) concentrations were significantly decreased by BaP compared with those of UNC rats. The decreases in circulating plasma testosterone were accompanied by concomitant increases in plasma LH concentrations in BaP-exposed versus control rats (P < 0.05). These data suggest that 60 days exposure to inhaled BaP contribute to reduced testicular endocrine and spermatogenic functions in exposed rats.