Anogenital distance in children born of mothers with polycystic ovary syndrome: the Odense Child Cohort

Higher free testosterone in the third trimester was associated with lower abdominal circumference at birth in boys: Odense child cohort

OBJECTIVE

To investigate associations between maternal testosterone status and offspring birth anthropometrics.

DESIGN

Population-based prospective cohort study.

SETTING

University Hospital.

POPULATION

1486 mother-child dyads from Odense Child Cohort.

METHODS

Maternal blood samples were collected at gestational weeks 27-30 and free testosterone (FT) levels were calculated using the Vermeulen equation from total testosterone (TT) analysed by mass spectrometry and sex hormone binding globulin. Associations between FT or TT levels and birth anthropometrics were analysed with multiple linear regression models according to offspring sex with adjustment for maternal age, parity, smoking and educational level. Analyses were repeated with polycystic ovary syndrome as exposure for offspring birth anthropometrics.

MAIN OUTCOME MEASURES

Offspring birth weight (BW), birth length, abdominal and head circumferences.

RESULTS

Maternal mean (SD) age was 30.2 (4.5) years and pre-pregnancy body mass index was 23.5 (5.3) kg/m2 . In boys (n = 787), higher FT was associated with lower birth weight (adjusted doubling constant = -65.53, P = 0.010), shorter birth length (adjusted doubling constant = -0.43, P < 0.001), and lower abdominal circumference (adjusted doubling constant = -0.39, P < 0.001); Higher TT was associated with lower abdominal circumference (adjusted doubling constant = -0.25, P = 0.028). In girls, no associations were found between maternal FT or TT and offspring anthropometrics.

CONCLUSIONS

Higher maternal free testosterone exposure was linked to reduced birth weight, length and abdominal circumference in boys, whereas girls were not susceptible to maternal testosterone exposure.

Effects of different volumes of ovariectomy on fertility and offspring development of rats

Objective

The purpose of this study was to explore the effect of removal of different volumes of ovarian tissue on fertility and offspring development of SD rats.

Methods

SD rats were randomly divided into 6 groups according to different volumes of ovariectomy: Sham group (n=6), non-ovariectomized; 25%-OVX group (n=6), with half of the left ovary excised; 50%-OVX group (n=5), with the left ovary excised; 75%-OVX group (n=5), with the left ovary and half of the right ovary excised; 87.5%-OVX group (n=6), with the left ovary and three quarters of the right ovary excised; 100%-OVX group (n=6), with bilateral ovaries excised. These female rats (F0) were mated with healthy male rats one and four months after the surgery, and the offspring of F0 rats were named F11mon and F14mon, respectively. The number of days from mating to delivery and number of live cubs were recorded. At postnatal day 21 (P21), the body weight, length and anogenital distance (AGD) of the cubs were measured.

Results

There were no differences in the number of live cubs between 25%-OVX, 50%-OVX and sham groups. Rats in the 87.5%-OVX group did not give birth at 1 month and 4 months after the operation. When compared with the sham group, the body weight and length of F11mon at P21 were increased in 25%-OVX group and 50%-OVX group. However, after the second delivery, we controlled each mother's lactation to no more than eight pups. As a result, there were no differences in the body weight, length and AGD of F14mon compared with sham group.

Conclusion

Removal of less than 50% of the ovaries did not affect the fertility of rats and offspring development of rats.

Longer anogenital distance in female fetus of diabetic and obese pregnant women

OBJECTIVE

Previous studies revealed that prenatal exposure to androgen excess such as polycystic ovary syndrome (PCOS) is associated with offspring's anogenital distance (AGD) length, and AGD is a biomarker of intrauterine androgen exposure. This study aims to investigate a possible relationship of fetal AGD with maternal diabetes and obesity, and to evaluate whether AGD predicts the fetal androgen exposure related to diabetes and obesity in female fetus. This study is the first to focus on the relationship between offspring's AGD and maternal diabetes and obesity.

MATERIALS AND METHODS

This is a prospective study investigating 218 pregnant women (125 in control group and 93 in study group). Fetal AGD was measured from the center of anus to the posterior convergence of the fourchette by ultrasound. Multivariate linear regression analysis was applied to assess the association of the fetal AGD length with maternal diabetes and obesity.

RESULTS

The control patients had significantly shorter fetal AGD (mean:10.7 mm, P < 0.001) compared to diabetic, obese and diabetic obese patients (mean: 12.6 mm, 12.8 mm and 12.9 mm, respectively). The results of regression analysis showed that both maternal diabetes and obesity were significantly correlated with longer AGD in female fetus. The results confirmed also that offspring's AGD measurement in utero by ultrasound is feasible and reliable.

CONCLUSION

The study findings suggest that both maternal diabetes and obesity are associated with intrauterine androgenic milieu during pregnancy, and fetal AGD may be used as a biomarker to predict this effect. This may provide important advantages in terms of early detection of reproductive system abnormalities related to prenatal androgen exposure.

Prenatal Androgen Exposure and Traits of Autism Spectrum Disorder in the Offspring: Odense Child Cohort

Fetal androgen exposure may be associated with autism spectrum disorder (ASD). We studied 1777 mother-child pairs in the prospective Odense Child Cohort. Prenatal androgen exposure was assessed by maternal 3rd trimester testosterone concentrations, maternal polycystic ovary syndrome (PCOS), and 3 months offspring anogenital distance. ASD traits were assessed at age 3 years with the ASD-symptom scale of the Child Behavior Checklist for ages 1½-5 years. Maternal testosterone was positively associated with traits of ASD in boys (p < 0.05). Maternal PCOS was associated with increased offspring ASD traits (p = 0.046), but became non-significant after excluding parental psychiatric diagnosis. Offspring anogenital distance was not linked to ASD traits. Higher prevalence of ASD in boys could be linked to higher susceptibility to fetal androgen exposure.

The effect of polycystic ovary syndrome history on neonatal anogenital distance: A prospective study in Turkish population

Aim: Embryonic anogenital length depends on fetal sex and testosterone. Children of women with a history of polycystic ovary syndrome (PCOS) who became pregnant may have different anogenital lengths due to hyperandrogenemia. Therefore, the aim of this study was to compare the anogenital lengths of male and female newborns of women with and without a history of PCOS. Material and Method: The study was designed prospectively. Pregnant women with PCOS and control group who gave birth at term (≥37-42 weeks) between March 2019 and March 2020 in XXX, Department of Obstetrics and Gynecology (blind review) were included in this study. Results: A total of 119 patients, including 21 mothers with PCOS and female newborns, 35 mothers with female newborns in the control group, 21 mothers with PCOS and male newborns and 42 mothers with male newborns in the control group, were included in this prospective study. Anogenital distance-anus fourchette (AGD-AF) measurement was significantly higher in the female newborns from mother with PCOS than in the female newborns from control group (18.1±2.5 vs. 14.1±1.6, p=0.046). Also, AGD-AF was 20.3±3.5 in the PCOS with hirsutism group and 15.2±1.5 in the PCOS without hirsutism group, and the difference between them was statistically significant (p=0.041). Conclusion: The anogenital distance may change in female newborns in the presence of maternal PCOS. Considering that AGD reflects fetal testosterone exposure, the findings may reflect increased testosterone exposure in female fetuses of pregnant women with PCOS. The results pave the way for new studies.

Deconstructing a Syndrome: Genomic Insights Into PCOS Causal Mechanisms and Classification

Polycystic ovary syndrome (PCOS) is among the most common disorders in women of reproductive age, affecting up to 15% worldwide, depending on the diagnostic criteria. PCOS is characterized by a constellation of interrelated reproductive abnormalities, including disordered gonadotropin secretion, increased androgen production, chronic anovulation, and polycystic ovarian morphology. It is frequently associated with insulin resistance and obesity. These reproductive and metabolic derangements cause major morbidities across the lifespan, including anovulatory infertility and type 2 diabetes (T2D). Despite decades of investigative effort, the etiology of PCOS remains unknown. Familial clustering of PCOS cases has indicated a genetic contribution to PCOS. There are rare Mendelian forms of PCOS associated with extreme phenotypes, but PCOS typically follows a non-Mendelian pattern of inheritance consistent with a complex genetic architecture, analogous to T2D and obesity, that reflects the interaction of susceptibility genes and environmental factors. Genomic studies of PCOS have provided important insights into disease pathways and have indicated that current diagnostic criteria do not capture underlying differences in biology associated with different forms of PCOS. We provide a state-of-the-science review of genetic analyses of PCOS, including an overview of genomic methodologies aimed at a general audience of non-geneticists and clinicians. Applications in PCOS will be discussed, including strengths and limitations of each study. The contributions of environmental factors, including developmental origins, will be reviewed. Insights into the pathogenesis and genetic architecture of PCOS will be summarized. Future directions for PCOS genetic studies will be outlined.

Update on Animal Models of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex disease affecting up to 15% of women of reproductive age. Women with PCOS suffer from reproductive dysfunctions with excessive androgen secretion and irregular ovulation, leading to reduced fertility and pregnancy complications. The syndrome is associated with a wide range of comorbidities including type 2 diabetes, obesity, and psychiatric disorders. Despite the high prevalence of PCOS, its etiology remains unclear. To understand the pathophysiology of PCOS, how it is inherited, and how to predict PCOS, and prevent and treat women with the syndrome, animal models provide an important approach to answering these fundamental questions. This minireview summarizes recent investigative efforts on PCOS-like rodent models aiming to define underlying mechanisms of the disease and provide guidance in model selection. The focus is on new genetic rodent models, on a naturally occurring rodent model, and provides an update on prenatal and peripubertal exposure models.

Associations of maternal anthropometrics with newborn anogenital distance and the 2:4 digit ratio

STUDY QUESTION

Are maternal anthropometrics associated with anogenital distance (AGD) and 2:4 digit ratio (2:4D) in newborns?

SUMMARY ANSWER

Select maternal anthropometrics indicative of obesity or increased adiposity are associated with elongated AGD in daughters.

WHAT IS KNOWN ALREADY

Excessive maternal weight or adiposity before or in early pregnancy may impact child reproductive, and other hormonally mediated, development. AGD and 2:4D are proposed markers of in utero reproductive development.

STUDY DESIGN, SIZE, DURATION

This study includes 450 mother/newborn dyads participating in the Illinois Kids Development Study (I-KIDS), a prospective pregnancy cohort from Champaign-Urbana, IL, USA. Participants included in the current study enrolled between 2013 and 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Most mothers in this study were college-educated (82%) and non-Hispanic White (80%), and 55% were under- or normal weight before pregnancy. Pregnant women aged 18-40 years reported pre-pregnancy weight and height to calculate pre-pregnancy BMI. At 8-15 weeks gestation, we measured waist and hip circumference, and evaluated weight, % body fat, visceral fat level, % muscle and BMI using bioelectrical impedance analysis. Within 24 h of birth, we measured newborn 2nd and 4th left/right digits to calculate the 2:4D. In daughters, we measured AGDAF (anus to fourchette) and AGDAC (anus to clitoris). In sons, we measured AGDAS (anus to scrotum) and AGDAP (anus to base of the penis).

MAIN RESULTS AND THE ROLE OF CHANCE

Select maternal anthropometrics were positively associated with AGD in newborn daughters, but not sons. For example, AGDAC was 0.73 mm (95% CI: 0.15, 1.32) longer for every interquartile range (IQR) increase in pre-pregnancy BMI and 0.88 mm (95% CI: 0.18, 1.58) longer for every IQR increase in hip circumference, whereas AGDAF was 0.51 mm (95% CI: 0.03, 1.00) and 0.56 mm (95% CI: 0.03, 1.09) longer for every IQR increase in hip and waist circumference, respectively. Quartile analyses generally supported linear associations, but additional strong associations emerged in Q4 (versus Q1) of maternal % body fat and visceral fat levels with AGDAC. In quartile analyses, we observed only a few modest associations of maternal anthropometrics with 2:4D, which differed by hand (left versus right) and newborn sex. Although there is always the possibility of spurious findings, the associations for both measures of female AGD were consistent across multiple maternal anthropometric measures, which strengthens our conclusions.

LIMITATIONS, REASONS FOR CAUTION

Our study sample was racially and ethnically homogenous, educated and relatively healthy, so our study may not be generalizable to other populations. Additionally, we may not have been powered to identify some sex-specific associations, especially for 2:4D.

WIDER IMPLICATIONS OF THE FINDINGS

Increased maternal weight and adiposity before and in early pregnancy may lengthen the female AGD, which warrants further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

This publication was made possible by the National Institute for Environmental Health Sciences (NIH/NIEHS) grants ES024795 and ES022848, the National Institute of Child Health and Human Development grant R03HD100775, the U.S. Environmental Protection Agency grant RD83543401 and National Institute of Health Office of the Director grant OD023272. Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the US EPA or NIH. Furthermore, the US EPA does not endorse the purchase of any commercial products or services mentioned in the publication. This project was also supported by the USDA National Institute of Food and Agriculture and Michigan AgBioResearch. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Maternal Testosterone Concentrations in Third Trimester and Offspring Handgrip Strength at 5 Years: Odense Child Cohort

BACKGROUND

Maternal testosterone in pregnancy may have conditioning effects on offspring muscle strength.

PURPOSE

To investigate possible associations between maternal testosterone concentrations in third trimester and offspring handgrip strength (HGS) at 5 years.

METHODS

In the prospective, population-based Odense Child Cohort, total testosterone (TT) at gestational week 27-28 and 5-year HGS were measured in 1017 mother-child pairs. TT was measured by liquid chromatography-tandem mass spectrometry and free testosterone (FT) was calculated from TT and sex hormone-binding globulin (SHBG). Multivariable regression analyses were performed with HGS < 10th percentile as cutoff for low HGS.

RESULTS

Third-trimester FT concentration was 0.004 (0.002-0.007) nmol/L, geometric mean (mean - SD; mean + SD). The mean (SD) 5-year HGS was 8.7 (1.8) kg in boys and 8.1 (1.7) kg in girls (P < 0.001). Higher FT concentrations were associated with lower HGS (β = -0.186, P = 0.048), after adjustment for maternal age, parity, offspring sex, and 5-year height and weight. FT > 0.004 nmol/L was associated with higher risk of 5-year HGS < 10th percentile with odds ratios (95% CI) of 1.58 (1.01, 2.47; P = 0.047; n = 1,017) and 1.69 (1.05, 2.74; P = 0.032) after further adjustment for children's organized sports in subgroup analysis (n = 848). Lower HGS in relation to higher FT concentrations was found in all linear models but was not always statistically significant. HGS was not associated with maternal TT and SHBG levels.

CONCLUSION

Third trimester FT was inversely associated with offspring muscle strength assessed by HGS at 5 years of age, which may suggest a negative effect of maternal FT on offspring muscle strength.

Sex-specific ranges and ratios for anogenital distance among Thai full-term newborns

Introduction

Anogenital distance (AGD) is a marker of prenatal androgen exposure and a tool for assessment of differences of sex development. Data for AGD in newborns have been published, but these findings may not be applicable to Thai newborns.

Aim

To provide the sex-specific ranges for AGD in Thai full-term newborns.

Methods

A cross-sectional study was conducted in term newborns in Thailand, during 2016–2018. AGD was measured from anus to anterior base of penis (AGD_AP) and to perineoscrotal junction (AGD_AS) in males and from anus to clitoris (AGD_AC) and to posterior fourchette (AGD_AF) in females. AGD ratio is defined as AGD_AS divided by AGD_AP in males and AGD_AF divided by AGD_AC in females.

Results

A total of 364 newborns were studied (male 51.4%). The mean AGD_AS, AGD_AP and AGD ratio in males were 25.20 ± 4.80, 52.60 ± 6.90 and 0.48 ± 0.08 mm, respectively. The mean AGD_AF, AGD_AC, and AGD ratio in females were 16.50 ± 3.90, 42.60 ± 6.20 and 0.39 ± 0.08 mm, respectively. There were significant differences between AGD_AS and AGD_AF, AGD_AP and AGD_AC, and AGD ratio between males and females (p < 0.001). The AGD_AS, AGD_AP, AGD_AF, AGD_AC were correlated with birth weight and length, but AGD ratio showed no correlation.

Conclusion

The sex-specific ranges for AGD in Thai full-term newborns were determined. AGD ratio is a useful marker of prenatal androgen exposure since it differs between sexes, but constant between races and did not vary by body size.

The role of gonadotropin-releasing hormone neurons in polycystic ovary syndrome

Given the critical central role of gonadotropin-releasing hormone (GnRH) neurons in fertility, it is not surprising that the GnRH neural network is implicated in the pathology of polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility. Although many symptoms of PCOS relate most proximately to ovarian dysfunction, the central reproductive neuroendocrine system ultimately drives ovarian function through its regulation of anterior pituitary gonadotropin release. The typical cyclical changes in frequency of GnRH release are often absent in women with PCOS, resulting in a persistent high-frequency drive promoting gonadotropin changes (i.e., relatively high luteinizing hormone and relatively low follicle-stimulating hormone concentrations) that contribute to ovarian hyperandrogenemia and ovulatory dysfunction. However, the specific mechanisms underpinning GnRH neuron dysfunction in PCOS remain unclear. Here, we summarize several preclinical and clinical studies that explore the causes of aberrant GnRH secretion in PCOS and the role of disordered GnRH secretion in PCOS pathophysiology.

Variation among human populations in endometriosis and PCOS A test of the inverse comorbidity model

Evidence linking endometriosis to low prenatal testosterone, and evidence that risk of polycystic ovary syndrome (PCOS) is associated with high prenatal testosterone, have motivated the hypothesis that endometriosis and PCOS exhibit inverse comorbidity. The inverse comorbidity hypothesis predicts that populations exhibiting higher prevalence of one disorder should show lower prevalence of the other. To test this prediction, data were compiled from the literature on the prevalence of endometriosis and PCOS, levels of serum testosterone in women during pregnancy and digit ratios as indicators of prenatal testosterone, in relation to variation in inferred or observed population ancestries. Published studies indicate that rates of endometriosis are highest in women from Asian populations, intermediate in women from European populations and lowest in women from African populations (i.e. with inferred or observed African ancestry); by contrast, rates of PCOS show evidence of being lowest in Asian women, intermediate in Europeans and highest in individuals from African populations. Women from African populations also show higher serum testosterone during pregnancy (which may increase PCOS risk, and decrease endometriosis risk, in daughters), and higher prenatal testosterone (as indicated by digit ratios), than European women. These results are subject to caveats involving ascertainment biases, socioeconomic, cultural and historical effects on diagnoses, data quality, uncertainties regarding the genetic and environmental bases of population differences and population variation in the causes and symptoms of PCOS and endometriosis. Despite such reservations, the findings provide convergent, preliminary support for the inverse comorbidity model, and they should motivate further tests of its predictions.

Lay Summary: Given that endometriosis risk and risk of polycystic ovary syndrome show evidence of having genetically, developmentally, and physiologically opposite causes, they should also show opposite patterns of prevalence within populations: where one is more common, the other should be more rare. This hypothesis is supported by data from studies of variation among populations in rates of endometriosis and PCOS and studies of variation among populations in levels of prenatal testosterone, which mediaterisks of both conditions.

Maternal polycystic ovary syndrome and attention deficit hyperactivity disorder in offspring at 3 years of age: Odense Child Cohort

INTRODUCTION

Previous data suggested a link between maternal polycystic ovary syndrome (PCOS) and offspring attention deficit hyperactivity disorder (ADHD), which could be mediated by higher prenatal androgen exposure.

MATERIAL AND METHODS

The study was part of the prospective Odense Child Cohort and included 1776 pregnant women, 165 (9%) with PCOS and 1607 (91%) controls. ADHD symptoms at 3 years of age were defined using the parent-reported questionnaire Child Behavior Checklist/1.5-5 (scores >90th centile of Danish national standard). Maternal blood samples were collected in the third trimester measuring total testosterone by mass spectrometry, sex hormone-binding globulin, and calculated free testosterone. Offspring anogenital distance was measured at 3 months of age. Regression models were performed with presence of ADHD symptoms as the dependent variable and adjusted for maternal age, body mass index, parity, smoking status, educational level, and parental psychiatric diagnoses.

RESULTS

ADHD symptoms were present in 105/937 (11%) boys and 72/839 (9%) girls. In boys, maternal PCOS was positively associated with ADHD symptoms (unadjusted odds ratio [OR] 1.91, 95% CI 1.07-3.43, p = 0.03, adjusted OR 2.20, 95% CI 1.20-4.02, p = 0.01), whereas maternal PCOS was not associated with ADHD symptoms in girls. Maternal total testosterone, free testosterone, and offspring anogenital distance were not associated with higher risk of ADHD symptoms in the offspring.

CONCLUSIONS

Higher risk of ADHD in boys born of mothers with PCOS were not associated with maternal third-trimester testosterone levels or offspring anogenital distance.

Endometriosis and polycystic ovary syndrome are diametric disorders

Evolutionary and comparative approaches can yield novel insights into human adaptation and disease. Endometriosis and polycystic ovary syndrome (PCOS) each affect up to 10% of women and significantly reduce the health, fertility, and quality of life of those affected. PCOS and endometriosis have yet to be considered as related to one another, although both conditions involve alterations to prenatal testosterone levels and atypical functioning of the hypothalamic-pituitary-gonadal (HPG) axis. Here, we propose and evaluate the novel hypothesis that endometriosis and PCOS represent extreme and diametric (opposite) outcomes of variation in HPG axis development and activity, with endometriosis mediated in notable part by low prenatal and postnatal testosterone, while PCOS is mediated by high prenatal testosterone. This diametric disorder hypothesis predicts that, for characteristics shaped by the HPG axis, including hormonal profiles, reproductive physiology, life-history traits, and body morphology, women with PCOS and women with endometriosis will manifest opposite phenotypes. To evaluate these predictions, we review and synthesize existing evidence from developmental biology, endocrinology, physiology, life history, and epidemiology. The hypothesis of diametric phenotypes between endometriosis and PCOS is strongly supported across these diverse fields of research. Furthermore, the contrasts between endometriosis and PCOS in humans parallel differences among nonhuman animals in effects of low versus high prenatal testosterone on female reproductive traits. These findings suggest that PCOS and endometriosis represent maladaptive extremes of both female life-history variation and expression of sexually dimorphic female reproductive traits. The diametric disorder hypothesis for endometriosis and PCOS provides novel, unifying, proximate, and evolutionary explanations for endometriosis risk, synthesizes diverse lines of research concerning the two most common female reproductive disorders, and generates future avenues of research for improving the quality of life and health of women.

Update on PCOS: Consequences, Challenges, and Guiding Treatment

Polycystic ovary syndrome (PCOS) is one of the most common reproductive endocrine disorders in women and despite this, diagnostic challenges, delayed diagnosis, and less-than-optimal treatment regimens plague the condition. The International PCOS network, consisting of geographically diverse international experts in PCOS as well as consumers, engaged in a multi-year international evidence-based guideline development process that was jointly sponsored by the European Society for Human Reproduction and Embryology (ESHRE) and the American Society of Reproductive Medicine (ASRM). The guideline was published in 2018 and endorsed by more than 40 international societies involved in PCOS. Translation of this evidence-based guideline to medical practice and consumer groups remains a priority. However, there remain many challenges to both understanding the diagnosis and treatment of PCOS. Evidence suggests that both clinicians and consumers are not satisfied with the timeliness of diagnosis and treatment options. This review summarizes the important findings for diagnosis and treatment from the guidelines and expands on recent developments in the literature since its publication. Special attention to diagnosis at the ends of the reproductive spectrum are discussed and remaining areas of controversy are noted. Additionally, the review highlights some of the remaining challenges in the understanding and management of PCOS to help guide clinicians and investigators in this perplexing condition.

Abnormal GnRH Pulsatility in Polycystic Ovary Syndrome: Recent Insights

Although the fundamental symptoms of polycystic ovary syndrome (PCOS) relate most directly to ovarian dysfunction, central neuroendocrine systems play a prominent role in its pathophysiology. Gonadotropin-releasing hormone (GnRH) pulse generator resistance to negative feedback contributes to rapid GnRH pulse secretion, which promotes gonadotropin abnormalities that foster ovarian hyperandrogenemia and ovulatory dysfunction. The causes of GnRH neuron dysfunction, however, have remained enigmatic. In this review, we highlight a number of recent preclinical and clinical studies pertinent to the neuroendocrine abnormalities of PCOS, including those that have provided important insights into the relevance of animal models with PCOS-like features, the potential roles of kisspeptin and γ-aminobutyric acid (GABA)-ergic neurons, and the potential role of anti-Müllerian hormone.