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PubMed1996

A male-specific role for SOX9 in vertebrate sex determination.

Mutation analyses of patients with campomelic dysplasia, a bone dysmorphology and XY sex reversal syndrome, indicate that the SRY-related gene SOX9 is involved in both skeletal development and sex determination. To clarify the role SOX9 plays in vertebrate sex determination, we have investigated its expression during gonad development in mouse and chicken embryos. In the mouse, high levels of Sox9 mRNA were found in male (XY) but not female (XX) genital ridges, and were localised to the sex cords of the developing testis. Purified fetal germ cells lacked Sox9 expression, indicating that Sox9 expression is specific to the Sertoli cell lineage. Sex specificity of SOX9 protein expression was confirmed using a polyclonal antiserum. The timing and cell-type specificity of Sox9 expression suggests that Sox9 may be directly regulated by SRY. Male-specific expression of cSOX9 mRNA during the sex determination period was also observed in chicken genital ridges. The conservation of sexually dimorphic expression in two vertebrate classes which have significant differences in their sex determination mechanisms, points to a fundamental role for SOX9 in testis determination in vertebrates. Sox9 expression was maintained in the mouse testis during fetal and adult life, but no expression was seen at any stage by in situ hybridisation in the developing ovary. Male-specific expression was also observed in the cells surrounding the Müllerian ducts and in the epididymis, and expression in both sexes was detected in the developing collecting ducts of the metanephric kidney. These results suggest that SOX9 may have a wider role in the development of the genitourinary system.

Animals↗
PubMed1983

Corpus luteum formation in the fetus.

A well-developed corpus luteum was found at autopsy in a premature infant who died 26 hours post partum. Intrauterine pituitary-gonadal development and regulation are briefly reviewed and a possible mechanism of intrauterine fetal ovulation is presented.

Adult↗
PubMed1999

Identification of genes expressed in human primordial germ cells at the time of entry of the female germ line into meiosis.

In mammals, primordial germ cells (PGCs) are first observed in the extraembryonic mesoderm from where they migrate through the hindgut and its mesentery to the genital ridge to colonize the developing gonads. Soon after reaching the gonads, the female PGCs enter meiosis, while the male PGCs are arrested in mitosis and enter meiosis postnatally. To gain an insight into the molecular events controlling human germ cell development, we determined specific profiles of gene expression using cDNA prepared from PGCs isolated from male and female fetal gonads at 10 weeks gestation, when female PGCs start to enter meiosis. The identity of the isolated PGCs, and the cDNA molecules prepared from them, was confirmed respectively, by alkaline phosphatase staining and by the presence of transcripts of OCT4, a marker gene for PGCs and pluripotent stem cells in mice. Using differential display to compare the profiles of gene expression of male and female germ cells with each other and with that of a whole 10 week old fetus, we have identified eight transcripts differentially expressed in male and/or female germ cells. Among these transcripts, we have identified a member of the olfactory receptor gene family, which contains genes known to be germline-specific in the dog and possibly associated with chemotactic function. Another transcript is common to a previously isolated sequence from the human testis and we have extended this sequence towards the 5' end for partial characterization. The germline-specific sequences also include two novel sequences not represented in the databases. These findings are highly encouraging for the elucidation of the genetic programming of male and female germ line development.

Alkaline Phosphatase↗
PubMed1999

Reproductive condition and behavior in relation to plasma levels of gonadal steroids in the spiny damselfish Acanthochromis polyacanthus.

Gonadal condition and plasma levels of gonadal steroids were measured in relation to behavior in the biparental brood-protecting spiny damselfish Acanthochromis polyacanthus. Fish were captured by SCUBA divers from natural populations on Australia's Great Barrier Reef and immediately bled underwater, following diver or video observation of precapture behaviour. In winter (July), most fish were nonterritorial, with a low proportion of mature males, or vitellogenic females present. In spring (November), most fish were territorial with broods of young at varying stages of maturity, and all stages of gonadal development were represented. Territorial males were larger than nonterritorial fish, but territorial fish that had large (older) young (the end of the brooding phase) had lower condition factors than fish at other stages. Males of all gonad stages had a high proportion of spermatozoa in the testis, but this was higher in November than in July. Ovaries of females commonly had several classes of developing follicles present, although fish that were brooding large young had regressed ovaries with a high incidence of atresia. Plasma levels of testosterone (T) and 11-ketotestosterone were elevated in males of advanced gonadal maturity, and also in relation to recent or imminent spawning behaviour, but there were no changes in plasma 17, 20beta-dihydroxy-4-pregnen-3-one (17,20betaP), which was near assay detection limits at all times. Females had elevated T and 17beta-estradiol (E2) in association with vitellogenesis and elevated T in relation to spawning activity in some fish, but as in males, 17,20betaP levels were low and unchanging. Territorial females without young had lower cortisol levels than nonterritorial fish, or females protecting young. The results confirm the importance of elevated androgens to spawning activity in territorial male fish, but not females where endocrine activity is more closely related to stage of ovarian development. Extended brooding appears to inhibit vitellogenesis, perhaps via a stress-related mechanism.

Animals↗
PubMed1995

Testicular steroid biosynthesis in a boy with a large cell calcifying Sertoli cell tumor producing prepubertal gynecomastia.

A study of a large cell calcifying Sertoli cell tumor of the testis associated with bilateral gynecomastia in an 8-year-old boy is presented. Macroscopically, the two testes showed multiple, large, and hard calcified nodules. Histology revealed clusters or cords of tumor cells with foci of calcifications as well as evidences, in the adjacent testicular parenchyma, of initiation of gonadal development, such as early signs of spermatogenesis and sparse Leydig cell differentiation. In vivo, serum hormone studies showed gonadotropin-independent gonadal activity. After orchidectomy two macroscopically distinct fractions of the removed testes, tumoral and extratumoral, were processed separately for cell isolation and culture. The secretion of testosterone, androstenedione, and 17-hydroxyprogesterone to the medium on day 6 of culture showed that steroidogenesis in cells of the extratumoral fraction was more active than in the tumoral fraction. On the other hand, tumoral fraction cells showed much higher aromatase activity than extratumoral cells. Furthermore, conditioned medium of tumoral fraction cells was able to stimulate testosterone secretion when it was added to subcultures of testicular cells isolated from a control subject. It is postulated that tumoral cells might have stimulated neighboring interstitial cells to differentiate into Leydig cells and to secrete androgens, which in turn might have been aromatized to estrogens by tumoral cells.

Adult↗
PubMed1996

Cellular distribution of EGF, TGFalpha and their receptor during postnatal development and spermatogenesis of the boar testis.

The epidermal growth factor (EGF), the transforming growth factor alpha (TGFalpha) and the epidermal growth factor receptor (EGFr) have been immunolocalized, (i) during the testicular postnatal development (i.e. at the perinatal, prepubertal and adult periods), and (ii) during the seminiferous epithelium cycle in the different germ cell types. While TGFalpha was essentially observed in somatic cells, specifically in perinatal Leydig cells and in mature Sertoli cells, EGF was localized both in germ cells and in somatic cells with a preferential tubular expression. Furthermore, identification of EGFr in different testicular cell types indicates that during postnatal development and spermatogenesis, testicular cells are potentially responsive to EGF in that they express EGFr. Indeed, in the course of the gonadal development, the EGFr distribution was evidenced both in somatic and germ cells with a specific germ cell pattern depending upon the seminiferous epithelium cycle. A predominant EGFr staining was evidenced during the meiotic process and the spermiogenesis. Together, the present data are in favor of the involvement of the TGFalpha/EGF system in the local control of testicular cells during development and particularly of its potential direct implication in crucial steps of spermatogenesis such as meiosis and spermiogenesis.

Aging↗
PubMed2005

Endocrine correlates of the breeding asynchrony between two Corsican populations of blue tits (Parus caeruleus).

Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the first results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy different oak habitats and are separated by only 25 km. Despite their close proximity, they show a one-month difference in onset of egg laying, even after controlling for altitude. This micro-geographic difference in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum song activity during the egg-laying stage while maximal testosterone levels and testes sizes were reached 2-3 weeks before egg laying. The rate of development of the reproductive system in males was much faster in the earlier population, in spite of a similar onset of gonad development and song activity for the two study populations. No change in the volume of the song-control nuclei (HVC and RA) could be detected during the study period. Development of brain nuclei was completed 2-3 months before the beginning of intense sexual activity.

Animals↗
PubMed2002

A nuclear export signal within the high mobility group domain regulates the nucleocytoplasmic translocation of SOX9 during sexual determination.

In mammals, male sex determination starts when the Y chromosome Sry gene is expressed within the undetermined male gonad. One of the earliest effect of Sry expression is to induce up-regulation of Sox9 gene expression in the developing gonad. SOX9, like SRY, contains a high mobility group domain and is sufficient to induce testis differentiation in transgenic XX mice. Before sexual differentiation, SOX9 protein is initially found in the cytoplasm of undifferentiated gonads from both sexes. At the time of testis differentiation and anti-Müllerian hormone expression, it becomes localized to the nuclear compartment in males whereas it is down-regulated in females. In this report, we used NIH 3T3 cells as a model to examine the regulation of SOX9 nucleo-cytoplasmic shuttling. SOX9-transfected cells expressed nuclear and cytoplasmic SOX9 whereas transfected cells treated with the nuclear export inhibitor leptomycin B, displayed an exclusive nuclear localization of SOX9. By using SOX9 deletion constructs in green fluorescent protein fusion proteins, we identified a functional nuclear export signal sequence between amino acids 134 and 147 of SOX9 high mobility group box. More strikingly, we show that inhibiting nuclear export with leptomycin B in mouse XX gonads cultured in vitro induced a sex reversal phenotype characterized by nuclear SOX9 and anti-Müllerian hormone expression. These results indicate that SOX9 nuclear export signal is essential for SOX9 sex-specific subcellular localization and could be part of a regulatory switch repressing (in females) or triggering (in males) male-specific sexual differentiation.

3T3 Cells↗
PubMed1999

Gonadal stage-dependent effects of gonadal steroids on gonadotropin II secretion in the Atlantic croaker (Micropogonias undulatus).

Involvement of gonadal steroids in the control of gonadotropin II (GTH II) (homologous to LH) secretion was investigated in the Atlantic croaker (Micropogonias undulatus) using gonadectomy (Gx) and steroid replacement paradigms. Gonadectomy in males and females during the late gonadal recrudescence phase elicited significant increases in the gonadotropin response to stimulation by an LHRH analog (LHRHa), without altering basal GTH II secretion. Slow-release silicone elastomer implants of testosterone or estradiol significantly inhibited LHRHa-induced GTH II secretion in gonad-intact and Gx males, and in Gx females, whereas 5alpha-dihydrotestosterone, a nonaromatizable androgen, was ineffective. Pretreatment of fish with an aromatase inhibitor, 1,4, 6-androstatrien-3,17-dione, 2 days before the administration of testosterone implants, completely blocked the negative effect of testosterone on LHRHa-induced GTH II secretion in males, but only partially restored it in females. This suggests that the negative feedback of testosterone in males is primarily mediated by its conversion to estradiol at the level of the hypothalamus and/or pituitary gland, while in females the androgen may also exert a direct inhibitory effect on GTH II secretion, probably mediated via an androgen receptor. In addition, estradiol and testosterone exerted positive effects on basal and LHRHa-induced GTH II secretion during the early-recrudescence phase of the gonadal cycle. The steroids switched to a negative effect on LHRHa-induced GTH II secretion once the fish had fully developed gonads, possibly as a mechanism that prevents a precocious surge in GTH II secretion and final gamete maturation until gametogenesis is complete and the environmental conditions are appropriate for spawning.

Animals↗
PubMed2002

Friend of GATA (FOG)-1 and FOG-2 differentially repress the GATA-dependent activity of multiple gonadal promoters.

The GATA transcription factors are crucial regulators of cell-specific gene expression in many tissues. GATA proteins are abundantly expressed in gonads of several species. In vertebrates, GATA factors are expressed from the onset of gonadal development and are later found in multiple cell lineages of both the testis and ovary. GATA factors activate transcription of several gonadal genes including the hormone-encoding genes Müllerian inhibiting substance (MIS) and inhibin alpha and genes involved in steroidogenesis like P450 aromatase (Cyp 19) and steroidogenic acute regulatory protein. GATA factors also contribute to cell-specific gonadal gene expression through cooperative interactions with other transcription factors such as the orphan nuclear receptor steroidogenic factor-1. GATA transcriptional activity is also modulated by two multitype zinc finger proteins called the Friend of GATA (FOG) proteins, which were cloned as GATA-specific cofactors. The FOG proteins (FOG-1 and FOG-2) can act as either enhancers or repressors of GATA transcriptional activity, depending on the cell and promoter context. We now report that the FOG proteins are coexpressed with GATA factors in testicular cells in which they differentially repress the promoter activities of several GATA-dependent target genes. These findings implicate the FOG proteins in the regulation of GATA-dependent gene transcription in the gonads.

Animals↗
PubMed1995

Anti-müllerian hormone and anti-müllerian hormone type II receptor messenger ribonucleic acid expression during postnatal testis development and in the adult testis of the rat.

Anti-müllerian hormone (AMH) induces degeneration of the müllerian ducts during male sex differentiation and may have additional functions concerning gonadal development. In the immature rat testis, there is a marked developmental increase in AMH type II receptor (AMHRII) messenger RNA (mRNA) expression in Sertoli cells, concomitant with the initiation of spermatogenesis. AMHRII mRNA is also expressed at a high level in Sertoli cells in adult rats. To obtain information about the possible functions of AMH in the testis, we investigated the postnatal expression patterns of the genes encoding AMH and AMHRII in the rat testis in more detail. Using RNase protection assays, AMH and AMHRII mRNA expression was measured in total RNA preparations from testes or testicular tubule segments isolated from control rats and from rats that had received various treatments. The testicular level of AMHRII mRNA was found to be much higher than that of AMH mRNA in adult rats. AMH mRNA was detected at a maximal level at stage VII of the spermatogenic cycle and at a low level at the other stages. AMHRII mRNA increases from stage XIII, is highest at stages VI and VII, and then rapidly declines at stage VIII to almost undetectable levels at stages IX-XII. It was found that the increase in testicular AMHRII mRNA expression during the first 3 weeks of postnatal development also occurs in sterile rats (prenatally irradiated), and hence, is independent of the presence or absence of germ cells. Yet, the total testicular level of AMHRII mRNA was decreased in sterile adult rats (prenatally irradiated or experimental cryptorchidism), as compared with intact control rats. However, treatment of adult rats with methoxyacetic acid or hydroxyurea, which resulted in partial germ cell depletion, had no effect on total testicular AMHRII mRNA expression. We conclude that a combination of multiple spermatogenic cycle events, possibly involving changes of Sertoli cell structure and/or Sertoli cell-basal membrane interactions, regulate autocrine AMH action on Sertoli cells, in particular at stage VII of the spermatogenic cycle.

Age Factors↗
PubMed1987

Complete and incomplete Drash syndrome: a clinicopathologic study of five cases of a dysontogenetic-neoplastic complex.

Drash syndrome is a complex disorder characterized by abnormal renal function, abnormal sexual differentiation with predisposition to developing gonadal neoplasms, and nephroblastoma. The authors report five cases with various manifestations of this syndrome. Dysgenetic gonads and abnormal sexual differentiation were present in all patients; two had unilateral and two bilateral gonadoblastomas; in addition, one of the latter had a juvenile granulosa cell tumor. Renal failure was present in all patients. One patient had bilateral Wilms' tumor, and one patient had a metanephric hamartoma. Each element of the triad in this syndrome is analyzed with regard to possible pathogenetic mechanisms and current models of carcinogenesis. Cases with complete forms of the syndrome reported in the literature are reviewed. Patients with incomplete forms of the syndrome must be followed carefully because other elements of this complex may become manifest.

Child, Preschool↗
PubMed1993

Control of testicular cycles in the song sparrow, Melospiza melodia melodia: interaction of photoperiod and an endogenous program?

Adult male song sparrows, Melospiza melodia melodia, underwent testicular development accompanied by increases in plasma levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) regardless of photoperiods tested. Although gonadal development progressed rapidly in birds exposed to long days, males subjected to short day lengths also showed testicular growth between 90 and 200 days. Onset of photorefractoriness during exposure to continual long days was highly variable among individuals. Short days were not required to regain photosensitivity, and thus spontaneous testicular recrudescence occurred in birds held on long days for prolonged periods. However, cycles of testicular mass, length of cloacal protuberance, and prebasic-type molt in birds held on continuous long days became dissociated and were erratic. It males held on short days were exposed to 1 long day (18L 6D) and then returned to short days, a rapid increase in testicular mass and plasma levels of LH and FSH followed. The effect of 1 long day was greater if males had been exposed to short days for 2 months or longer. Thus, although short days were not absolutely required for dissipating photorefractoriness, they apparently accelerate the process. Female song sparrows showed a similar response to 1 long day. Input from changing day length was also important for triggering testicular regression. Male song sparrows held on 16L 8D for 10 months showed no signs of prebasic molt or testicular regression. When half of the males in this group were then exposed to 14L 10D (a shorter day length but still photostimulatory in spring), there were rapid declines in testis mass and FSH levels. These results are consistent with the phenomenon of "relative photorefractoriness," in which decreased day length results in gonadal regression despite the fact that similar day lengths would have been photostimulatory earlier in spring. It is suggested that song sparrows have "programs" of gonadal activity and molt that are not usually expressed in captivity as part of a complete cycle. The annual change in day length may act to drive the cycle, as continual environmental input for entraining endogenous programs to exactly 1 year and for scheduling the correct temporal sequence of events. Such a combination of continual environmental input and endogenous rhythms may be widespread.

Animals↗
PubMed2006

Xenopus laevis is a potential alternative model animal species to study reproductive toxicity of phytoestrogens.

This study investigated effects of phytoestrogen quercetin on the gonadal development in Xenopus laevis. X. laevis at Nieuwkoop and Faber stage 46/47 were exposed to 50, 100 and 200 microg/L quercetin till 1 month postmetamorphosis. Gonads from frogs at 1 and 3 months postmetamorphosis were examined in gross morphology and histology. The highest dose of quercetin as well as estradiol (E2) significantly increased the percentages of phenotypic females. Exposure to quercetin at all doses induced abnormal testes with certain ovarian characteristics to some degree in gross morphology, including ovotestes. The abnormality rate exceeded 10% in each quercetin treatment. Histologic examination revealed that some abnormal testes exhibited intersexuality with testicular structure and ovarian structure or oocytes interspersed in testicular structure at 1 month postmetamorphosis. At 3 months postmetamorphosis, testicular abnormalities were more obvious, such as necrosis or apoptosis of spermatogonia, occurrence of developed or undeveloped oocytes, delay of the development of seminiferous tubes without or less late stage spermatocytes. The results have shown that quercetin cannot only feminize but also impair testicular development of X. laevis, i.e. X. laevis is sensitive to phytoestrogen. It is suggested that X. laevis might be an alternative model species to study reproductive toxicity of phytoestrogens.

Animals↗
PubMed2006

Tandem-repeated Zebrafish zp3 genes possess oocyte-specific promoters and are insensitive to estrogen induction.

Zona pellucida (Zp) proteins are glycoproteins in fish chorion and are encoded by multiple gene families, including zp1, zp2, zp3, and potentially other zp genes. Expression of zp genes in teleosts is either in the liver under the induction of estrogen or in the ovaries. In the present study, we isolated and characterized a zebrafish zp3 genomic clone and found three tandem-repeated zp3 genes with high sequence identities. We estimated that there were 10-15 zp2 and 17-21 zp3 genes in a haploid genome. We also found some variant zp2 and zp3 subfamilies, and each subfamily may have multiple members. These zp2 and zp3 genes are distributed in several different chromosomes. Ontogenetic expression of zp2 and zp3 mRNAs was first detected at 3 wk postfertilization, which was about 5 wk earlier than initial vtg1 expression, indicating that ovary development was earlier than vitellogenesis. Both zp2 and zp3 mRNAs were expressed specifically in early-growing oocytes and are insensitive to estrogen induction. Because zp3 genes are organized in tandem repeats, to investigate whether an individual zp3 promoter is capable of driving oocyte-specific expression, green fluorescence protein (gfp)-transgenic zebrafish were developed by using a 3.8-kb zp3 5' upstream region, and we found that the gfp reporter gene was faithfully expressed in developing oocytes in zp3:gfp transgenic females. Thus, the new transgenic line not only provided a convenient living marker for monitoring female gonad development, but also demonstrated that a single zp3 gene promoter is sufficient for oocyte-specific transcription.

Amino Acid Sequence↗
PubMed2002

Ontogeny and distribution of gonadotropin-releasing hormone (GnRH) neuronal systems in the brain of the cichlid fish Cichlasoma dimerus.

Using immunocytochemistry we have described the distribution and ontogeny of three distinct gonadotropin-releasing hormone (GnRH) neural systems, emphasizing the analysis during the period of sex differentiation in the South American cichlid fish Cichlasoma dimerus. In the forebrain a group of neurones immunoreactive to salmon GnRH that formed clusters in the nucleus olfacto retinalis (NOR), was located at the junction of the olfactory bulb and the telencephalon. These neurones differentiated 3 days after fertilization from the olfactory placodes. GnRH immunoreactive neurones along the olfactory nerves through the rostrobasal olfactory bulb were observed on day 4 and at the NOR on day 10. A group of neurones immunoreactive to chicken GnRH II was seen in the dorsal midbrain tegmentum. They originate from the ventricular ependyma between days 5 and 6. These neurones remained close to blood vessels throughout development. Between days 22 and 30 a group of neurones immunoreactive to seabream GnRH was detected in the anterior basal preoptic area. GnRH innervation of the pituitary was detected after the differentiation of preoptic neurones and in coincidence with gonadal differentiation. We hypothesize that the GnRH neural systems have three distinct embryonic origins. Furthermore, we show that the NOR and the midbrain GnRH neurones might have functions other than gonadal development, whereas the preoptic GnRH neurones in C. dimerus might be associated with gonadal sex differentiation.

Animals↗
PubMed1975

Effect of steroids on definitive localization of primordial germ cells in the chick embryo.

It has been suggested that PGCs are attracted to developing gonads by a chemotactic-like agent secreted by the gonads and that this agent might be steroidal in nature. This study was undertaken to ascertain whether specific exogenous steroid hormones exert an influence on germ cell colonization of the gonads, by enhancing, inhibiting or otherwise interfering with it. Testosterone cypionate in cottonseed oil, crystalline testosterone propionate, estrone in aqueous suspension and crystalline estradiol-17beta were adminstered to chick embryos at 33 hours incubation. Normally developed embryos, those receiving cottonseed oil (vehicle for testosterone cypionate) and those receiving cholesterol served as controls. A decrease in the number of germ cells in the gonadal area at five days of incubation occurred in all groups receiving the androgens and estrogens. However, in only one group (that receiving testosterone cypionate) was this decrease found to be significant. The mean number of germ cells found in the cottonseed oil controls and the cholesterol controls closely paralleled that of the normally developed controls. Normal asymmetry in the distribution of the germ cells favoring the left side in the chick was not affected in any of the groups; however, the percentage distribution of the germ cells between the right and left gonads at this early stage appeared to be affected.

Androgens↗
PubMed1987

Effects of long-term exposure to cythion on the reproduction of the teleost fish, Channa punctatus (Bloch).

The chronic toxic effects of an organophosphorus pesticide on some aspects of the physiology of reproduction in a teleost fish, Channa punctatus, are described in this investigation. Fish exposed to 2.0 mg litre(-1) of commercial cythion continuously for 6 months, from January (resting phase) to June (spawning phase), exhibited a significant inhibition of gonadal development and gonadosomatic index. These changes were correlated with less active, and a reduced number of, pituitary gonadotrophs, and biochemical changes in the gonads and liver. The immature oocytes of the experimental fish exhibited cytoplasmic proteinaceous 'inclusion bodies', which ultimately led to their degeneration. The results suggest that cythion may act directly on the gonads and/or through the pituitary-gonadal axis, in this species.

Journal Article↗