Abnormal Sexual Differentiation Research Articles

Testis determination requires insulin receptor family function in mice.

In mice, gonads are formed shortly before embryonic day 10.5 by the thickening of the mesonephros and consist of somatic cells and migratory primordial germ cells. The male sex-determining process is set in motion by the sex-determining region of the Y chromosome (Sry), which triggers differentiation of the Sertoli cell lineage. In turn, Sertoli cells function as organizing centres and direct differentiation of the testis. In the absence of Sry expression, neither XX nor XY gonads develop testes, and alterations in Sry expression are often associated with abnormal sexual differentiation. The molecular signalling mechanisms by which Sry specifies the male pathway and models the undifferentiated gonad are unknown. Here we show that the insulin receptor tyrosine kinase family, comprising Ir, Igf1r and Irr, is required for the appearance of male gonads and thus for male sexual differentiation. XY mice that are mutant for all three receptors develop ovaries and show a completely female phenotype. Reduced expression of both Sry and the early testis-specific marker Sox9 indicates that the insulin signalling pathway is required for male sex determination.

A Mutated Form of Steroidogenic Factor 1 (SF-1 G35E) That Causes Sex Reversal in Humans Fails to Synergize with Transcription Factor GATA-4

Steroidogenic factor 1 (SF-1) is a transcription factor belonging to the nuclear receptor superfamily. SF-1 regulates the expression of many genes involved in reproduction, steroidogenesis, and sexual differentiation. An important SF-1 target for male sexual differentiation is the gene encoding the Müllerian-inhibiting substance hormone that induces regression of the Müllerian ducts in the developing male embryo. Not long ago, a mutation (G35E) in the human SF-1 gene was identified as the cause of sex reversal and adrenal failure in a phenotypically female but genotypically XY individual. This suggested that the mutated SF-1 protein might interfere with the expression of SF-1 target gene(s) involved in the male sexual differentiation pathway, such as MIS. Surprisingly, the initial biochemical characterization of the SF-1 G35E mutant revealed that it could bind and activate the MIS promoter as efficiently as wild-type SF-1. MIS expression, however, does not rely solely on SF-1 but rather requires the concerted action of several transcription factors including GATA-4. We have previously reported that GATA-4 and SF-1 transcriptionally cooperate to synergistically activate the MIS promoter. Thus, we hypothesized that the phenotype observed with the SF-1 G35E mutation could be explained, at least in part, by a failure and/or a disruption of GATA-4/SF-1 synergism. We found that the SF-1 G35E mutant failed to synergize with GATA-4 despite a direct physical interaction between the two proteins. Interestingly, the SF-1 G35E mutant also disrupted transcriptional synergism between wild-type SF-1 and GATA-4, indicating that it could act as a dominant negative competitor. Thus, our results strengthen the importance of a GATA-4/SF-1 cooperation for MIS transcription and reveal that disruption of this synergism might be responsible for some cases of abnormal sex differentiation in humans.

Clustering of sex hormone disruptors in Singapore's marine environment.

Abnormal sexual differentiation and other reproductive abnormalities in marine animals indicate the presence in seawater of endocrine-disrupting compounds (EDCs) that perturb the function of the sex hormone signaling pathways. However, most studies to date have reported on EDC effects in freshwater and sewage samples, and there is a paucity of bioassay data on the effects of EDCs in marine waters. Our aims in this study were to devise robust methodologies suitable for extracting potential EDCs and to measure their summated effects on activities of androgen receptors (ARs) and estrogen receptors (ER-alpha and ER-beta) in marine samples from Singapore's coastal waters. In this study, we examined the ability of C18, hydrophilic and lipophilic balance, and diol cartridges to extract potential EDCs from seawater samples. Extracts from C18 cartridges exhibited the highest sex hormone bioactivities in reporter gene assays based on a human cell line expressing AR, ER-alpha, and ER-beta. Examination of extracts from 20 coastal locations showed high androgenic and estrogenic agonist activities in confined clusters closest to the main island of Singapore. Sex hormone activity declined rapidly in clusters farther from the main coastline and in more open waters. Unexpectedly, surface and mid-depth samples from the confined high-activity clusters, in the presence of hormone, exhibited AR and ER-alpha activities that were 200-900% higher than those observed for the cognate hormone alone. This enhanced sex hormone activity suggests that analyses of complex seawater mixtures may uncover unusual bioactivities that may not be obvious by studying individual compounds. Our data present a "snapshot" of the sex hormone disruptor activity in Singapore's marine environment and indicate that C18 extraction for EDCs used in conjunction with reporter gene bioassays represents a robust and sensitive methodology for measuring summated androgenic and estrogenic activities in seawater.

Fish full life‐cycle testing for the weak estrogen 4‐tert‐pentylphenol on medaka (Oryzias latipes)

We studied the chronic effects of 4-tert-pentylphenol (4-PP) on reproductive status of medaka (Oryzias latipes) over two generations under continuous exposure, with the goal of verifying the applicability of the fish full life-cycle test (FFLC) for this weak estrogen with this species. The exposure of parental (F0) medaka to 4-PP was begun on embryos within 12 h after fertilization and continued for up to 101 d, with monitoring of embryological development, hatching, posthatch survival, growth, sexual differentiation, reproduction, and hepatic vitellogenin (VTG) levels under flow-through exposure to 4-PP at mean measured concentrations of 51.1, 100, 224, 402, and 931 microg/L. Eggs (F1) spawned from the F0 fish at 99, 100, and 101 d after hatch also were examined for hatchability, survival after hatching, growth, sexual differentiation, and hepatic VTG levels, until 61 d after hatch. In the FFLC with the F0 medaka, the lowest-observed-effect concentration (LOEC) of 4-PP for lethal and sublethal toxicity (as shown by growth inhibition) was 931 microg/L. The LOECs for estrogenic effects (as shown by abnormal sexual differentiation and VTG induction) were 224 and < or = 51.1 microg/L, respectively, and the LOEC for reproductive impairment was 224 microg/L. Therefore, the effective concentrations of 4-PP for abnormal sexual differentiation and reproductive impairment were about four times lower than those for lethal and sublethal toxicity. In the F1 medaka, the LOECs for sublethal toxicity and estrogenic effects were 224 and < or = 51.1 microg/L, respectively. This finding suggests that the continuous exposure to 4-PP over two generations induced these adverse effects at lower concentrations in the F1 generation than those in the F0 generation. Thus, 4-PP has estrogenic effects that reduce the reproductive potential of medaka. The results indicate that the FFLC with medaka is applicable to the evaluation of weak estrogens.

Effects of 4‐nonylphenol and 4‐tert‐octylphenol on sex differentiation and vitellogenin induction in medaka (Oryzias latipes)

Medaka (Oryzias latipes) were continuously exposed to various concentrations of two alkylphenols, 4-nonylphenol (NP) and 4-tert-octylphenol (OP), from fertilized eggs to 60 d posthatch. The effects on sexual differentiation and hepatic vitellogenin (VTG) induction in medaka were assessed to elucidate the lowest-observed-effect concentrations (LOECs) of NP and OP for these events during early life stages. The LOECs of NP and OP for these events were 11.6 and 11.4 microg/L, respectively. These results suggest that NP and OP may have adverse effects at similar concentrations during early life stage in medaka. Additionally, we investigated whether the abnormal sex differentiation induced by these alkylphenols would be permanent or reversible once the medaka were returned to clean water. The appearance of the secondary sex characteristics reverted from female to male when fish were returned to clean water. However, gonadal histology showed that intersex gonads still existed, even after the fish were transferred to clean water for two months. These results suggest that the induced feminization of secondary sex characteristics in medaka exposed to alkylphenols during the stage of sexual differentiation may not always be permanent, but the gonadal alteration (testis-ova) may continue much longer.

Human sex differentiation and its abnormalities

The purpose of this chapter is to review the presentation and management of patients affected by conditions of abnormal sex differentiation. First, the processes of normal sex differentiation are covered, followed by an overview of the various syndromes of abnormal sex differentiation, or intersex conditions, that can occur. These disorders are presented according to the following categories: patients who possess a 46,XX chromosome complement, those who possess a 46,XY chromosome complement, and individuals who present with an atypical sex chromosome complement (i.e. 45,XO or 45,X0/46,XY mosaicism). A description of the medical, surgical and psychological treatment options for people affected by various intersex conditions and reared as females are included. Practice points, based on research studies when available, are dispersed throughout the chapter. Additionally, information pertaining to relevant Internet websites and patient support groups are provided, so that medical staff can educate their patients about the availability of these resources.

Mutational analysis of Hungarian patients with androgen insensitivity syndrome.

To support the clinical diagnosis of androgen insensitivity syndrome (AIS), we performed mutational analysis of the androgen receptor gene. Clinical, hormonal and molecular genetic data of ten undervirilized genetic male patients living in Hungary were recorded. PCR-based single strand conformation polymorphism (SSCP) analysis was used to study the whole coding region of the androgen receptor gene. Direct fluorescent sequencing was applied when aberrant migration was detected by SSCP. Five different mutations were identified in five unrelated genetic male patients with abnormal sexual differentiation. One of these mutations was novel, while the other four mutations have been described previously in the literature. One of the mutations identified earlier in individuals with sporadic AIS showed a familial inheritance pattern in our study group. No abnormality of the androgen receptor gene was identified in three patients clinically suspected to have partial AIS. Application of molecular techniques helped to clarify the diagnosis in patients with disorders of male sexual differentiation.

Surgical management and genotype/phenotype correlations in WT1 gene–related diseases (drash, frasier syndromes)

Background/Purpose: The WT1 gene plays a role in urogenital and gonadal development. Germline mutations of this gene have been observed in patients with Drash or Frasier syndrome (Sd). The purpose of this report is to compare phenotype and genotype of these patients. Methods: Retrospective study of 12 patients treated since 1980 for WT1 gene–related disorders was conducted. Results: End-stage renal disease (ESRD) occurred in 9 patients, mostly because of diffuse mesangial sclerosis (DMS) or focal and segmental glomerular sclerosis (FSGS). Seven patients underwent kidney transplantation, and 2 died. Eleven tumors occurred: 8 Wilms' tumors, one soft tissue tumor, one bladder papilloma, and one gonadoblastoma. Wilms' tumors occurred at a younger age than expected. Eight patients had a 46,XY karyotype. One of these XY patients had female phenotype (Frasier syndrome); she was raised as a girl with bilateral gonadectomy. Seven XY patients had ambiguous phenotype; 4 have been raised as boys and 3 as girls. Four patients had a 46,XX karyotype; they had female genitalia and were raised as girls. WT1 gene analysis was performed in 10 patients and showed heterozygous germline mutations in exon 9 (n = 6), intron 9 (n = 1), exon 3 (n = 1), exon 4 (n = 1), or exon 7 (n = 1). Conclusions: ESRD was secondary to DMS when exon 9 was mutated, and secondary to FSGS when intron 9 was mutated. When exon 3, 4, and 7 were mutated, no nephropathy has been observed. Wilms' tumors occurred with any kind of WT1 mutation except intron 9. Abnormal sexual differentiation has been observed in all XY patients with WT1 mutation, and the most profound inversion of phenotype was observed with mutation in intron 9. Correlation between phenotype and genotype provides better understanding of the role of WT1, and can help the surgeon in the management of these patients. J Pediatr Surg 38:124-129. Copyright 2003, Elsevier Science (USA). All rights reserved.

Genetics of the mineralocorticoid system in primary hypertension.

Abnormalities in steroid biosynthesis have been known for years to cause hypertension in some cases of congenital adrenal hyperplasia. In these patients hypertension usually accompanies a characteristic phenotype with abnormal sexual differentiation. Recently, the molecular basis of four forms of severe hypertension transmitted on an autosomal basis but without additional phenotypic features has been elucidated. All these conditions are characterized primarily by low plasma renin, normal or low serum potassium, and salt-sensitive hypertension, indicating an increased mineralocorticoid effect. These four disorders, the glucocorticoid remediable aldosteronism, the syndrome of apparent mineralocorticoid excess, the activating mutation of the mineralocorticoid receptor, and the Liddle syndrome are a consequence of either abnormal biosynthesis, metabolism, or action of steroid hormones, and are ultimately characterized by an overactivation of the epithelial sodium channel in distal renal tubules. Hyperactivity of this channel results in increased sodium reabsorption and volume expansion leading to an increase in blood pressure as well as potassium loss. With the advent of molecular biology in clinical practice, it has become evident that some genetic defect may present with a more discrete phenotype, with only moderate hypertension with or without hypokalemia as the sole feature. A search for genetic disorders of the mineralocorticoid axis should be an integral part of the diagnostic work-up, particularly in young adults with hypertension.

Intersexuality and Gender Identity Differentiation

Over the past couple of decades, there have been some remarkable advances in understanding the biological processes that underlie both normal and abnormal physical sex differentiation. 1 Vilain E Genetics of sexual development. Ann Rev Sex Res. 2000; 11: 1 PubMed Google Scholar , 2 Vilain E McCabe E Mammalian sex determination From gonads to brain. Mol Genet Metabol. 1998; 65: 74 Abstract Full Text PDF PubMed Scopus (80) Google Scholar During this same time period, there has also been progress in understanding the mechanisms—both biological and psychological—that underlie psychosexual differentiation (a term that I define and decompose below) in people whose physical sex differentiation is normal and in people where it is not. 3 Ruble D Martin C Gender development. in: Damon W The Handbook of Child Psychology (5th ed.). Vol. 3. Social, Emotional, and Personality Development. New York, Wiley, N Eisenberg1998: 933-1016 Google Scholar , 4 Zucker K Biological influences on psychosexual differentiation. in: Unger R Handbook of the Psychology of Women and Gender. Wiley, New York2001: 101-115 Google Scholar

Environmental Endocrine Disrupters and Disorders of Sexual Differentiation

Endocrine disrupters are exogenous substances that cause adverse effects in the endocrine system. Sexual differentiation is regulated by reproductive hormones. Male differentiation is critically dependent on normal androgen action, which in turn depends on normal production of luteinizing hormone. Other essential hormones include follicle-stimulating hormone, anti-Müllerian hormone, and insulin-like hormone 3 (insl-3). Estrogens influence transcription of insl-3 and affect sexual differentiation both directly and indirectly. Diethylstilbestrol is the best known endocrine disrupter and has caused abnormalities of sexual differentiation in both exposed male and female human fetuses. There is a growing group of chemicals that have weak estrogenic properties, but, in addition, there are several antiandrogenic compounds that have been shown to disturb sexual differentiation in experimental animals. It is a challenge for endocrinologists to find out whether or not these chemicals or mixtures of them are involved in any of the abnormalities of human sexual differentiation.

Normal and Abnormal Sexual Differentiation: From Genes to Patient

Normal and Abnormal Sexual Differentiation: From Genes to Patient

Amphibians as a model for the study of endocrine disruptors

Evidence shows that environmental compounds can interfere with the endocrine systems of wildlife and humans. The main sink of such substances, called endocrine disruptors (EDs), which are mainly of anthropogenic origin, is surface water; thus, aquatic vertebrates such as fishes and amphibians are most endangered. Despite numerous reports on EDs in fishes, information about EDs in amphibians is scarce, and this paucity of information is of particular concern in view of the worldwide decline of amphibians. EDs could contribute to changes of amphibian populations via adverse effects on reproduction and the thyroid system. In amphibians, EDs can affect reproduction by (anti)estrogenic and (anti)androgenic modes of action that produce severe effects including abnormal sexual differentiation. ED actions on the thyroid system cause acceleration or retardation of metamorphosis, which may also affect population levels. Our broad knowledge of amphibian biology and endocrinology indicates that amphibians are very suitable models for the study of EDs. In particular, effects of EDs on the thyroid system triggering metamorphosis can be determined easily and most sensitively in amphibians compared to other vertebrates. A new classification of EDs according to their biological modes of action is proposed because EDs have quite heterogeneous chemical structures, which do not allow prediction of their biological effects. Methods and strategies are proposed for identification and risk assessment of EDs, whether as pure test substances or as mixtures from environmental samples. Effects of EDs on the thyroid system of amphibians can be assessed by a single animal model (Xenopus laevis), whereas the various types of reproduction need comparative studies to investigate whether general endocrine principles do exist among several species of anurans and urodeles. Thus, at least one anuran and one urodelean model are needed to determine ED interference with reproduction.

Long-term perspectives for 46,XY patients affected by complete androgen insensitivity syndrome or congenital micropenis.

Controversy concerning optimal treatment for individuals affected by syndromes of abnormal sex differentiation can best be resolved with knowledge about long-term medical, surgical, and psychosexual outcomes of patients. Follow-up information has recently been gathered on older cohorts of the following patient groups: (1) those affected by complete androgen insensitivity syndrome (CAIS) raised female and (2) those affected by congenital micropenis raised male or female. As a group, women with CAIS were satisfied with their female gender and sexual function. However, a need for better patient education was identified for this specific population. Most patients with congenital micropenis, whether raised male or female, were satisfied with their gender. Regardless of sex of rearing, dissatisfaction with the appearance and function of the genitalia as judged by both physicians and subjects was evident. For patients with congenital micropenis, male sex of rearing was concluded to be optimal because genital reconstructive surgery is not required with this choice.

Contribution of domestic animals to the identification of new genes involved in sex determination.

Among farm animals, two species present an intersex condition at a relatively high frequency: pig and goat. Both are known to contain XX sex-reversed individuals which are genetically female but with a true hermaphrodite or male phenotype. It has been clearly demonstrated that the SRY gene is not involved in these phenotypes. Consequently, autosomal or X-linked mutations in the sex-determining pathway may explain these sex-reversed phenotypes. A mutation referred to as "polled" has been characterized in goats by the suppression of horn formation and abnormal sexual differentiation. The Polled Intersex Syndrome locus (PIS) was initially located in the distal region of goat chromosome 1. The homologous human region has been precisely identified as an HSA 3q23 DNA segment containing the Blepharophimosis Ptosis Epicanthus locus (BPES), a syndrome combining Premature Ovarian Failure (POF) and an excess of epidermis of the eyelids. In order to isolate genes involved in pig intersexuality, a similar genetic approach was attempted in pigs using genome scanning of resource families. Genetic analyses suggest that pig intersexuality is controlled multigenically. Parallel to this work, gonads of fetal intersex animals have been studied during development by light and electron microscopy. The development of testicular tissue and reduction of germ cell number by apoptosis, which simultaneously occurs as soon as 50 days post coïtum, also suggests that several separate genes could be involved in pig intersexuality.

Recent advances in the molecular genetics of congenital and acquired primary adrenocortical failure.

IntroductionIn recent years there have been many advances in ourunderstanding of the molecular pathogenesis of both congenitaland acquired adrenocortical failure (autoimmune or otherwise).As well as providing some fascinating insights into adrenalgland development and steroid hormone biosynthesis, therecognition of these various distinct disorders, either at aclinical or molecular genetic level, often has implications forthe management of the patient and their immediate family. In thispaper, we review the salient clinical and molecular features of thevarious causes of primary adrenocortical failure (Table 1).Genetics of autoimmune Addison’s diseaseAutoimmune Addison’s disease (AAD) is a chronic disorder ofthe adrenal gland, characterized by insufficiency of adrenocor-tical hormones due to autoimmune destruction of steroidogenicadrenocortical cells (Oelkers, 1996). The cytochrome P450enzymes involved in steroidogenesis, including 21-hydroxylase(Baumann-Antczak et al., 1992; Winqvist et al., 1992), 17-hydroxylase (Krohn et al., 1992) and side chain cleavageenzyme (Winqvist et al., 1993) have been identified as primaryautoantigens in AAD. With the overall decrease in theprevalence of tuberculosis, AAD has emerged as the mostcommon cause of primary adrenal failure in developedcountries (Nerup, 1974; Kong & Jeffcoate, 1994). Nevertheless,AAD is a relatively rare endocrinopathy; recent epidemiologi-cal studies showing an estimated prevalence in the generalEuropean population of about 100 per million (Kong J Laureti et al., 1999).The results of human leucocyte antigen (HLA) typing, takentogether with the clinical heterogeneity of presentation anddifferent modes of inheritance, have suggested distinctpathogenic bases for different forms of AAD. Thus, AADmay occur in isolation, as a manifestation of the autoimmunepolyendocrinopathy type 1 syndrome (APS1), or as part of theautoimmune polyendocrinopathy type 2 (APS2) syndrome(Table 1) (Spinner et al., 1968; Neufeld et al., 1981; Maclaren& Riley, 1986).Autoimmune polyendocrinopathy type 1 syndrome: amonogenic autoimmune disorderIn the autoimmune polyendocrinopathy type 1 (APS1)syndrome, which is also known as the autoimmune poly-endocrinopathy, candidiasis and ectodermal dystrophy(APECED) syndrome, AAD occurs in association withautoimmune hypoparathyroidism, chronic mucocutaneous can-didiasis and other organ-specific autoimmune disorders. Theseinclude type 1 diabetes, primary gonadal failure, perniciousanaemia, chronic active hepatitis and hypothyroidism (Neufeldet al., 1981; Ahonen et al., 1990). The age of onset of AAD inAPS1 is typically between 11 and 15years, although othermanifestations of APS1 (e.g. hypoparathyroidism and candi-diasis) are likely to present at an earlier age. APS1 is amonogenic disorder with autosomal recessive inheritance,affecting both sexes with equal prevalence (Ahonen, 1985),and is rare in most populations. However, because of foundereffects, it is relatively common in the Finnish population andIranian Jews with estimated prevalences of 1/25000 and 1/9000, respectively (Ahonen, 1985; Zlotogora & Shapiro, 1992).Initial genetic studies of APS1 focused on HLA, and noassociation of this disorder with any specific HLA haplotypehas been found (Neufeld et al., 1981; Maclaren & Riley, 1986;Aaltonen et al., 1993; Huang et al., 1996). The gene underlyingAPS1 was subsequently localized on chromosome 21q22 bylinkage analysis (Aaltonen et al., 1994) and identified bypositional cloning (Finnish-German APECED consortium,1997; Nagamine et al., 1997). This gene, designated auto-immune regulator-1 (AIRE-1), encodes a 545 amino acidprotein that has two plant homeodomain (PHD)-type zinc-finger motifs, suggesting a role as a transcription factor(Finnish-German APECED consortium, 1997; Nagamine etal., 1997). AIRE-1 mRNA is expressed in lymphoid tissuesincluding thymus, lymph node and spleen, and possibly also inother tissues including the adrenal cortex (Finnish-GermanAPECED consortium, 1997; Nagamine et al., 1997), whichsuggests that it may have an important role in the developmentof a normal immune response.

Gonadoblastoma, Testicular and Prostate Cancers, and the TSPY Gene

The role of the Y chromosome in oncogenesis of human cancers has been somewhat controversial. Both gain and loss of the Y chromosome in different leukemia, lymphoma, and solid tumors have been reported (Abeliovich et al. 1994; Brothman 1997; Dave et al. 1996; Geburek et al. 1997; Jackson-Cook et al. 1996; Kirk et al. 1994; Konig et al. 1994; Mertens et al. 1997; Riske et al. 1994; Watanabe et al. 1996). Conceivably, both oncogenes and tumor-suppressor genes exist on this chromosome, and they may act at different points during tumorigenesis, particularly for cancers of male-specific organs, such as the testis and the prostate.

Cross genotype sex hormone treatment in two cases of hypogonadal osteoporosis.

Sex hormone deficiency is the most common cause of bone loss. Reduced bone mass and an increased risk for osteoporotic fractures have been described in hypogonadal subjects of both sexes. We present here the results of treating two patients showing abnormal sexual differentiation (an XX male and an XY female), who suffered from bone loss related to sex hormone deficiency, with cross genotype sex hormones. Patient 1 was an asymptomatic 39-yr-old XY female with complete androgen insensitivity. Her testes had been removed, and she later discontinued estrogen treatment. Patient 2, a 37-yr-old XX male, had congenital adrenal hyperplasia, which led to a masculine phenotype. He was ovariectomized and reared as a male. He was treated with glucocorticoids but refused androgen treatment for many years. We treated both patients with phenotypically matched sex hormones (patient 1 received conjugated estrogens 1.25 mg/day, and patient 2 received 250 mg testosterone every 4 weeks) and followed their bone mineral density (BMD) using dual-energy X-ray absorptiometry, urine calcium, and hydroxyproline excretion. Before treatment both patients had low sex hormones and highly elevated gonadotropins. As a result of treatment urine hydroxyproline excretion decreased from 45 and 26.7 mg/g creatinine to 15 and 15.9 mg/g creatinine in patients 1 and 2 respectively. In patient 1, lumbar BMD rose from 0.912gr/cm2 to 0.976gr/cm2 and femoral neck BMD rose from 0.716gr/cm2 to 0.836gr/cm2 after 4 years of treatment. In patient 2, lumbar BMD rose from 0.717gr/cm2 to 0.815gr/cm2 and the femoral neck BMD rose from 0.509gr/cm2 to 0.635gr/cm2 after 27 months of treatment. Phenotypically-matched sex hormone therapy in patients with abnormal sexual differentiation is essential not only to maintain external appearance but also for the preservation of bone mass.

Latent effects of pesticides and toxic substances on sexual differentiation of rodents.

In humans and rodents, exposure to hormonally active chemicals during sex differentiation can produce morphological pseudohermaphrodism (Schardein, 1993; Gray, 1992). For example, hormonally active drugs like DES (estrogenic), Danazol (androgenic), and progestins cause urogenital malformations in the reproductive tracts of humans and rodents. The current discussion will present new information on the effects of toxic chemicals and pesticides that act on reproductive development via novel mechanisms, including germ cell toxicity, antiandrogenicity, and Ah-receptor binding. Information will be presented that describes how exposure during critical stages of life to synthetic chemicals present in our environment, such as benzidine-based dyes, antiandrogenic fungicides, 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), and PCB congener 169, result in abnormal rodent sex differentiation. In rodents, perinatal exposure to fetal germ cell toxicants reduced the reproductive potential of female, and permanently reduced sperm production in male progeny. Phenotypic sex differentiation, however, was unaffected by these germ cell toxicants. In contrast, antiandrogenic drugs and fungicides induced profound alterations in phenotypic sex differentiation. Effects such as hypospadias, ectopic testes, vaginal pouches, agenesis of the ventral prostate, and nipple retention in male rats were observed commonly. Although these antiandrogens induced no permanent effects in female progeny, another class of chemicals, the Ah-receptor mediated toxicants, did reduce fertility in both male and female rat offspring. Cauda epididymal sperm numbers were reduced permanently in TCDD-exposed male rat and hamster progeny, and female progeny displayed malformations of the external genitalia. Other toxicants produced dramatic alterations of sex differentiation (uterus unicornis, agenesis of the vas and epididymis, and undescended testes), via mechanisms that have not been characterized yet. Since these adult/pubertal alterations resulted from gestational and/or neonatal exposures, future studies should include a comprehensive assessment of reproductive function after perinatal exposure because the developing animal is extremely sensitive to toxicants during sex differentiation, and many of the effects are difficult to detect until late in life.

Evidence of hypothalamic involvement in the mechanism of transplacental carinogenesis by diethylstilbestrol

Disruption of hypothalamic sex differentiation in the fetus is one hypothesis to explain female reproductive system anomalies and cancer arising from prenatal exposure to diethylstilbestrol (DES). To further test this hypothesis, breeding performance and behavior were monitored in a colony of mice exposed prenatally to DES, using a schedule previously shown to produce anomalies and cancer of the female reproductive system. Fertility decreased with age more rapidly in DES-exposed females than in control females. DES-exposed females were less accepting of the male than control females. These observations support the hypothesis of abnormal hypothalamic sex differentiation as a basic mechanism in DES transplacental carcinogenesis.