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.     

Suppression of fertility in male albino rats following the administration of 50% ethanolic extract of Aegle marmelos

BACKGROUND: Plants have served as a natural source of antifertility substances. The reactivated interest in the evaluation of some lead plants for fertility prompted us to undertake studies on the antifertility potential of Aegle marmelos leaves. STUDY DESIGN: Fifty percent ethanolic extract from the leaves of A. marmelos (AMLEt) was prepared. The effect of A. marmelos leaf extract on the reproductive system of male albino rats was investigated at three different doses, namely, 100, 200 and 300 mg(-1) kg (-1) day(-1) for each rat for 60 days. Recovery was also investigated after a withdrawal of 120 days. RESULTS: All the major accessory sex organs shed weight postadministration of the extract. There was a marked reduction in motility and density of the sperm derived from cauda epididymis of the treated animals. A. marmelos reduced fertility of male rats by 100% at the 300-mg dose level. Serum testosterone levels also decreased significantly in all the experimental groups. The protein, glycogen and lipid peroxidation content of the testes was significantly reduced at the highest dose level; a highly significant increase in testicular cholesterol was observed along with a highly significant reduction in the sialic acid contents of testes, epididymis and seminal vesicles. Blood tests did not point to distress in any of the vital organs. Withdrawal of the extract restored all the altered parameters including organ weights, fertility, testosterone levels and tissue biochemistry to control levels after 120 days. CONCLUSIONS: Taken together, it is inferred that the leaf extract of A. marmelos (AMLEt) suppresses fertility in male rats. Complete recovery of fertility was observed following the withdrawal of drug. Absence of any deleterious effect on the vital organs points to the safe use of the extract.     

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.     

Inhibin B in seminiferous tubules of human testes in normal spermatogenesis and in idiopathic infertility

Inhibin B is one of the most significant serum markers of spermatogenesis, but its testicular expression has been poorly studied. Inhibin B sensitivity as well as the ability to reflect the level and condition of spermatogenesis and forecast certain changes in reproductive homeostasis in males is still a subject of active discussion. The purpose of this study is to examine the level of expression of inhibin B in cells of human seminiferous tubules in normal and in pathological spermatogenesis (idiopathic infertility) by revealing the proportion of immunostaining cells for inhibin B. The research conducted included analysis of testicular tissue samples taken from 82 males diagnosed with infertility and nonobstructive azoospermia. The influence of inhibin on the germ cells of men aged 22–35 been analyzed using the immunohistochemical method. According to the obtained results, high expression of inhibin can be detected both in Sertoli (98.0 ± 2.66) and Leydig (94.0 ± 1.55) cells in patients suffering from focal spermatogenesis disorders (mixed atrophy), in comparison with the men in the control group (65.9 ± 0.44 and 12.0 ± 0.44, respectively). The level of inhibin expression in the cytoplasm of spermatogonia was 4.0 ± 0.22 in control group of fertile men, while it was significantly increased in patients with Sertoli cell-only syndrome with focal spermatogenesis (45.0 ± 0.44). In the case of severe lesion to the seminiferous tubules (e.g., tubular hyalinization), the lowest level of inhibin expression in Sertoli cells is detected, whereas the immunostaining in Leydig cells showed only slight changes. Further histological research of Sertoli cells and inhibin B expression is necessary because, according to our data, the degree of inhibin B expression may be a useful marker of Sertoli cells function which can lead to new findings in the concept of local reproductive homeostasis in testis that may be impaired in some forms of idiopathic infertility in males.

Abbreviations: β-TGF: β-transforming growth factor family; GCA: germ cell abnormalities/atypia; JS: Johnsen score; FSH: follicle stimulating hormone; TESE: testicular sperm extraction; LH: luteinizing hormone; F-Testo: free testosterone; ELISA: the enzyme-linked immunosorbent assay; CV: coefficient of variance; DR: range of definitions; AZF: azoospermia factorI; HC: immunohistochemical; HIER: heat induction of epitope retrieval; H&E: hematoxylin and eosin     

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.     

CONTROL OF SPERMATOGENESIS IN PRIMATE AND PROSPECT OF MALE CONTRACEPTION

The present review is a summary of mechanisms of spermatogenesis in primates with emphasis on anti-spermatogenesis of testosterone (T), gossypol, and “testicular heat stress” for development of male contraception. Both FSH and testosterone stimulate all phases of spermatogenesis. FSH is capable of amplifying the population of the differentiated spermatogonia (B1, B2, B3 and B4) and controls the spermatogonia production rate, and, in synergy with testosterone, regulating spermatogenesis in adult monkeys. Pituitary FSH beta gene expression is governed by a feedback of Beta inhibin, which is a major component of the testicular negative feedback signals. Beta inhibin secreted by Sertoli cells is in turn inhibited by testosterone from Leydig cells under the control of LH. Disturbance of the normal interaction of pituitary FSH with Sertoli cell Beta inhibin is responsible for azoospermia or oligozoospermia induced by exogenous T. Three possible regimens of T, gossypol and “heat stress” have been suggested for male contraception. They act on different sites and stages of spermatogenesis in testis or sperm activity in epididymis. Apoptosis induced by testosterone occurs mainly at stages VII–VIII of spermatogenesis while that by testicular “heat stress” mostly occurs at stages I–IV and X–XII. Low dose of gossypol mainly influences the sperm activity in the epididymis although it also acts on testicular spermatids.     

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.     

Effects of multiglycosides of Tripterygium wilfordii (GTW) on rat fertility and Leydig and Sertoli cells.

Primary cultures of rat Leydig and Sertoli cells were used to evaluate the direct effects of GTW on testicular cells and to compare these to the effects of gossypol acetate. Both GTW and gossypol acetate can affect the survival of Leydig and Sertoli cells. But Sertoli cells are much more sensitive than Leydig cells, either to gossypol acetate or GTW. Leydig and Sertoli cells all died when they were exposed to gossypol acetate or GTW at a dose of 3.0 micrograms/ml or 30 micrograms/ml, respectively, for 24 hours. The cell survival-time course demonstrated that the cell numbers were decreased after 2 hours, and especially so after 8 hours. No significant changes were observed in testosterone production in Leydig cells after 24 hours of exposure to 1.0-20 micrograms/ml GTW. The forward motility of epididymal spermatozoa was completely lost and fertility of rat was significantly inhibited after the treatment of GTW in vivo. It is concluded that GTW does affect the fertility of rat and viability of cultured rat Leydig and Sertoli cells.     

Effect of Tripterigium wilfordii Hook. f. on the fertility of rats

Studies were undertaken to assess the effect of the total glycosides extracted from Tripterigium wilfordii Hook. f. (GTW), a ready-made Chinese herb medicine, on the fertility of both male and female rats. In male rats, GTW was given by gastric gavage at a dose of 10 mg/kg per day, 6 days a week for 8 weeks. All the treated animals became infertile. The body weight growth was normal and the mating behavior was present. There was a drastic decrease in the viability of the epididymal spermatozoa, while the decrease in the sperm density, though significant, was far less marked. Seminiferous tubular damage was minimal and no perceptible change was observed in the Leydig and the Sertoli cells. All other parameters examined, including the serum testosterone level and the histology of various organs, were normal. In female rats, GTW given orally at a dose of 50 mg/kg per day on days 1-4 or 7-9 of pregnancy did not significantly affect the fertility. It is thus concluded that non-toxic dose of GTW can cause infertility in male rats, the mechanism of which may involve and interference in the function of the epididymal and/or testicular spermatozoa; in female rats, the dose regimens employed do not have significant anti-implantation or early-pregnancy termination effect.     

Environmental pollutant Aroclor 1242 (PCB) disrupts reproduction in adult male rhesus monkeys (Macaca mulatta)

Adult male rhesus monkeys (Macaca mulatta) were given oral treatment of either Aroclor 1242 or vehicle (corn oil and glycerol) at a dose of 200 microg/kg body wt/day for 6 months to investigate the effects of the pollutant on plasma testosterone and the morphology of testes and accessory glands. Aroclor 1242 treatment significantly decreased testicular size and testosterone levels in plasma and adversely affected spermatogenic activity by disrupting epithelial organization. All components of the germinal epithelium were greatly reduced. The spermatogonia were either hypertrophied or had shrunken vesiculated cytoplasm with distorted mitochondria and nuclear pyknosis. Changes were milder in the Sertoli cells, where nuclear infoldings were reduced. Characteristic features of treated Leydig cells were the presence of electron-dense and electron-opaque zones, appearing as plaques, cell membrane abnormalities, and high variability in nuclear shape and heterochromatin distribution. All the Aroclor 1242-treated accessory glands contained more connective tissue than their vehicle-treated counterparts. The epithelium contained many layers of irregularly shaped necrotic cells possessing stereocilia in the epididymides, either hypochromic and hypertrophied or hyperchromic and hypotrophied cells in the prostate and shrunken cuboidal cells with elongated nuclei in the seminal vesicles. In conclusion, Aroclor 1242 treatment causes severe structural alterations on gonads and accessory organs in adult male rhesus monkeys, and these effects could be mediated through both estrogen and Ah receptors.     

Fine Structure and Cytochemistry of the Morphogenesis of Round-Headed Human Sperm

Ejaculates and testicular biopsies of two infertile men were examined at ultrastructural and cytochemical levels. The two patients presented spermograms in which all the spermatozoa had globular heads. Wide Golgi areas and large masses of annulatae lamellae were evident during spermatogenesis. Abnormal acrosomal vesicles were evident during early spermatid stage. Among the late spermatids, there was a small group characterized by a fibrous sheath showing considerable malformation, and “spindle shaped body.” In Sertoli cells, detached acrosomes undergoing degeneration were noted. Low TPPase activity was found in Golgi complex and in abnormal acrosomal vesicles of early spermatids. As regards acid phosphatase, was localized in spermatocytes and in early spermatids, but not in late spermatids and mature spermatozoa. Leydig cells had high phosphatase activity.     

Intrauterine bisphenol A exposure leads to stimulatory effects on Sertoli cell number in rats

Using the optical disector for quantifying cell numbers, we investigated whether oral treatment of rats on days 6-21 of gestation with the weakly estrogenic bisphenol A (BPA, 0.1 or 50 mg/kg) or the highly estrogenic ethinyl estradiol (EE, 0.02 mg/kg) alters testicular histology, in those offspring 9-12 month of age. Since production of male germ cells depends on Sertoli cell number, possible changes in that parameter were investigated using unbiased stereology. Spermatogenesis was qualitatively normal in all groups. BPA increases Sertoli cell number per organ but not when expressed as per gram testis. EE did not affect cell number per organ but did affect numbers on a per gram testis basis due to a lowered testis weight. In contrast to the lowering of Sertoli cell numbers that might have been expected according to the estrogen hypothesis, intrauterine administration of these xenoestrogens in fact resulted in minor increases in Sertoli cell numbers and had no qualitative effect on spermatogenesis.     

THYROID HORMONES: THEIR ROLE IN TESTICULAR STEROIDOGENESIS

Thyroid hormones are important for growth and development of many tissues. Altered thyroid hormone status causes testicular abnormalities. For instance, juvenile hypothyroidism/neonatal transient hypothyroidism induces macroorchidism, increases testicular cell number (Sertoli, Leydig, and germ cells) and daily sperm production. Triiodothyronine (T3) receptors have been identified in sperm, developing germ cells, Sertoli, Leydig, and peritubular cells. T3 stimulates Sertoli cell lactate secretion as well as mRNA expression of inhibin- &#102, androgen receptor, IGF-I, and IGFBP-4. It also inhibits Sertoli cell mRNA expression of Müllerian inhibiting substance (MIS), aromatase, estradiol receptor, and androgen binding protein (ABP) and ABP secretion. T3 directly increases Leydig cell LH receptor numbers and mRNA levels of steroidogenic enzymes and steroidogenic acute regulatory protein. It stimulates basal and LH-induced secretion of progesterone, testosterone, and estradiol by Leydig cells. Steroidogenic factor-1 acts as a mediator for T3-induced Leydig cell steroidogenesis. Although the role of T3 on sperm, germ, and peritubular cells has not yet been completely studied, it is clear that T3 directly regulates Sertoli and Leydig cell functions. Further studies are required to elucidate the direct effect of T3 on sperm, germ, and peritubular cells.     

Long-term effects of lonidamine on mouse testes

Lonidamine (LND) [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid] is a well-known antispermatogenic drug. The aim of this study was to identify its possible long-term sequelae on the reproductive system of mice as compared with rats, where most data have been obtained until now. Sexually mature CD1 male mice were administered a single dose of LND (200 mg/kg bw by gavage) and killed 24 and 48 h, 6 days and 2, 4 and 8 weeks after the treatment. Testes were collected, weighed and (1) fixed in Bouin's solution for histological analysis or (2) reduced to monocellular suspensions and ethanol fixed to undergo flow cytometry (FCM) DNA content analysis. No effect on body weight and/or food consumption was observed in the treated group in comparison with the control group. Testicular weight was significantly reduced 24 h after the treatment. Reduced seminiferous epithelium with a progressive lack of intercellular cohesion and marked depletion of spermatids, infiltration of granulocytes, desquamation into the tubular lumen and increased intertubular spaces were present by 24 h after the treatment and persisted to a marked degree at 48 h, 6 days and 2 and 4 weeks up to a marked degeneration of tubular structures with absence of spermatogenesis. The same effects, albeit with a moderate severity, were still present 8 weeks after the treatment. As also detected by FCM, primary spermatocytes appeared to be the main cellular target. Sertoli and Leydig cells were remarkably spared. The histological findings are consistent with those previously observed in rats and point out that testicular damage may persist for several weeks after a single-dose administration. Findings are discussed in comparison with testicular toxicity elicited by other xenobiotics.     

Alteration in testicular cell components following transiently induced ischaemia in prepubertal bulls

The aim of the present study was to evaluate transient testicular ischaemia (induced using elastrator bands) in Jersey calves on testicular morphology and development. Treatments (at 27 +/- 5 days of age) consisted of control (0 h banding) and banding for 2, 4 or 8 h (n = 4 in each group). After castration (at 60 +/- 5 days of age), the right testis was used for calculation of cell components per testis according to the point-counting method. Bodyweight (59.8 +/- 6.2 kg) and scrotal circumference (SC) at banding (9.1 +/- 0.2 cm) did not differ between groups. Fresh testis weight, scrotal temperature immediately before band removal and daily SC growth were decreased in ischaemic (4 and 8 h) testes compared with controls (P < 0.05). In addition, the number of Sertoli and Leydig cells was significantly reduced in the 8 h ischaemic treatment group (P < 0.05). Transiently induced ischaemia significantly decreased the number of germ cells in the 8 h ischaemic treatment group (13 +/- 5 x 10(6) cells) compared with the 0, 2 and 4 h ischaemic treatment groups (38 +/- 6, 32 +/- 6 and 33 +/- 5 x 10(6) cells, respectively; P < 0.05). These results suggest that transiently induced ischaemia for 8 h significantly decreases the number of germ, Sertoli and Leydig cells in prepubertal testis.     

Evaluation of reversible contraceptive activities of Cuminum cyminum in male albino rats

Background

The aim of the present study was to evaluate the contraceptive efficacy of Cuminum cyminum (jeera) seeds in male albino rats.

Study Design

C. cyminum methanol extract (CcMtE) at dose levels of 100 and 200 mg/rat/day was orally administered to male rats for 60 days. The effect of the treatment on reproductive organs and fertility was investigated. Recovery and toxicity studies were also carried out.

Results

C. cyminum methanol extract fed to male rats for 60 days did not cause any alterations in the body weight, whereas the weight of testes, epididymides, seminal vesicles and ventral prostate were significantly reduced (p≤.001). Animals treated with CcMtE showed a marked reduction in sperm density in the cauda epididymis and testes and sperm motility in the cauda epididymis. Reduction in fertility was 69.0% and 76.0% in 100 and 200 mg/rat/day dose levels, respectively. The circulatory hormones were also reduced significantly. Testicular biochemical analysis of protein, sialic acid, glycogen, ascorbic acid and fructose indicated a marked decline, whereas testicular cholesterol content was significantly increased, which showed altered biochemistry of the reproductive organs. After CcMtE treatment, significant decreases (p≤.001) were observed in the number of testicular cells (i.e., spermatogonia, primary spermatocytes [preleptotene and pachytene], secondary spermatocytes and round spermatids); nonsignificant change was observed in the Sertoli cell count. The treatment had no effect on levels of serum protein, cholesterol, bilirubin, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea and hematological indices.

Conclusions

The present study shows that C. cyminum treatment resulted in the inhibition of spermatogenesis and fertility without producing apparent toxic effects.     

Therapeutic effects of quercetin against bisphenol A induced testicular damage in male Sprague Dawley rats

The present study was designed to investigate protective effects of quercetin against bisphenol A (BPA) induced testicular toxicity in male Sprague Dawley rats. Twenty adult male rats were divided into four groups. The first group served as the control and was provided with normal saline. The second group of rats was treated with 50 mg/kg of BPA dissolved in alcoholic saline. The third group received oral gavage of 50 mg/kg quercetin while the fourth group was treated with quercetin (50 mg/kg) along with BPA (50 mg/kg). All of the treatments were carried out for 52 days. Testicular tissues and epididymis were used for histology while blood plasma was used for hormonal and biochemical analysis. BPA administration resulted in a significant reduction in seminiferous tubule diameter and epithelial height with impaired spermatogenesis. Quercetin treatment resulted in restoration of spermatogenesis and reversal of histological damage. In addition, BPA treatment significantly reduced (p < 0.05) plasma testosterone level (ng/ml) while estrogen was not affected. Similarly, BPA caused a significant alteration in the lipid profile. Interestingly, quercetin treatment led to a marked increase in plasma testosterone, decrease in estrogen concentration, as well as a normalized lipid profile. In conclusion, results indicated that BPA administration induces toxic effects on testis and epididymis, impairs spermatogenesis, with an imbalance in hormonal levels and lipid profile while quercetin amended these toxic effects by restoring normal spermatogenesis, testicular tissue damage, and hormonal levels. This suggests that quercetin may be a potential therapeutic against BPA induced testicular toxicity.     

Quantitative analysis of germ cells and Leydig cells in rat made infertile with gossypol

This study utilized improved methods of fixation and plastic embedding to quantitatively evaluate the effects of gossypol on germ cells and Leydig cells in testes of rats made infertile with gossypol. Rats were fed by gavage with 10, 20 or 30 mg/kg per day of gossypol for 9 weeks; control animals received the vehicle alone. Numbers of A spermatogonia, preleptotene and pachytene spermatocytes, and step 7 or 8 spermatids per Sertoli cell were counted in stages VII-VIII of the cycle of the seminiferous epithelium. Although high doses (30 mg/kg) of gossypol produced a significant decrease in the relative number of germ cells compared with vehicle-treated controls, no significant deviation in the relative number of germ cells was noted between controls and rats made infertile with 10 or 20 mg/kg/day of gossypol. Stereologic techniques were used to assess the changes in the Leydig cells. No significant deviation in the Leydig cell morphology, cell number, or cell volume was noted as a result of gossypol treatment at the dose levels employed. It appears that germ cell depletion, such as that caused by high doses of gossypol, is not mediated by a change in Leydig cell function. The present report emphasizes the importance of studies to determine the minimal effective doses for gossypol's antifertility activity in animal models as well as in man.     

DIFFERENTIAL REGULATION OF INHIBIN SUBUNITS BY GERM CELLS IN HUMAN TESTES

Inhibin B is comprised of two dissimilar disulfide-linked subunits, termed α and βB, and is physiologically more important than inhibin A in the male. The aim of this study was to investigate testicular expression of inhibin subtypes in infertile men to uncover any interaction between Sertoli cells and germ cells. Ten azoospermic patients with Sertoli cell only syndrome (SCO) and 39 oligozoospermic men were included in this study. Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone concentrations were determined by chemiluminescence assays. The serum concentrations of inhibin B were measured by enzyme-linked immunosorbent assay. Immunohistochemical staining for the α-subunit, β A-subunit, and βB-subunit of inhibin were performed on testicular biopsy specimens. The results were that serum inhibin B was undetectable in azoospermic men with SCO, while it was 133.8?±?82.0?pg/ml in oligozoospermic men. There was little expression of βA in the testes of any patient. Expression of inhibin α and βB was observed in Sertoli cells. The percentage of Sertoli cells expressing inhibin α was similar in azoospermic patients with SCO (55.3%?±?20.6%) and in oligozoospermic patients (42.8%?±?30.4%). In contrast, expression of βB in Sertoli cells of azoospermic patients (24.9%?±?16.8%) was lower than in oligozoospermic men (43.4%?±?25.5%: P?=?0.0308). There are no significant correlations between testicular expression of inhibin βB and the serum inhibin B concentrations. The expression of inhibin βB by Sertoli cells is dependent on the coexistence of spermatogenic activity within these seminiferous tubules, explaining why the level of inhibin B is low in patients with SCO.