Cisplatin- and cyclophosphamide-induced primordial follicle depletion is caused by direct damage to oocytes

It is well established that DNA-damaging chemotherapies can cause infertility and ovarian endocrine failure by depleting the ovarian reserve of primordial follicles. Currently, no effective pharmacological therapies exist for the preservation of long-term fertility and ovarian function in female cancer patients, due to a limited understanding of the mechanisms of chemotherapy-induced follicle depletion. This study investigated the cellular targets, molecular mechanisms, and temporal course of ovarian reserve depletion following treatment with commonly used chemotherapeutic drugs. Adult female C57BL/6 mice were injected i.p. with saline, cisplatin (5mg/kg), or cyclophosphamide (300mg/kg); ovaries were harvested after 8 or 24 hours. Follicle counts showed depletion of all follicular stages 24 hours after administration of cisplatin or cyclophosphamide. Eight hours post-treatment, H2A histone family member X (γH2AX) immunofluorescence showed DNA double-stranded breaks at all follicular stages, including within primordial follicle oocytes. This staining was resolving by 24 hours, indicating that primordial follicle oocytes begin to undergo either apoptosis or repair in this timeframe. γH2AX-positive follicles were further examined to identify the specific cell types damaged. In primordial, transitional, and primary follicles, only oocytes sustained DNA damage, whereas in secondary and antral follicles, only somatic cells were affected. TUNEL staining confirmed that apoptosis occurs in these targeted cell types. Whilst multi-drug and multi-dose regimens were not examined, this study conclusively shows that cyclophosphamide and cisplatin cause direct damage to primordial follicle oocytes, which then undergo apoptosis. Therefore, future pharmacological strategies to prevent chemotherapy-induced infertility in females must specifically prevent primordial follicle oocyte death.

The primordial follicle reserve is not renewed after chemical or γ-irradiation mediated depletion

Reports indicate that germ-line stem cells present in adult mice can rapidly generate new oocytes and contribute to the primordial follicle reserve following conditions of ovotoxic stress. We further investigated the hypothesis that adult mice have the capacity to generate new oocytes by monitoring primordial follicle numbers throughout postnatal life and following depletion of the primordial follicle reserve by exposure to doxorubicin (DXR), trichostatin A (TSA), or whole-body γ-irradiation. We show that primordial follicle number remains stable in adult C57BL/6 mice between the ages of 25 and 100 days. However, within 2 days of treatment with DXR or TSA, primordial follicle numbers had declined to 65 and 51% respectively (P<0.05-0.01 when compared to untreated controls), with no restoration of follicle numbers evident after 7 days for either treatment. Furthermore, ovaries from mice subjected to sterilizing doses of γ-irradiation (0.45 or 4.5 Gy) revealed complete ablation of all primordial follicles 5 days after treatment, with no indication of follicular renewal. We conclude that neo-folliculogenesis does not occur following chemical or γ-irradiation mediated depletion of the primordial follicle reserve.

168. TGFβ 2-BETAGLYCAN REGULATE FOETAL TESTIS DEVELOPMENT IN VITRO

Betaglycan is a co-receptor for the TGFβ superfamily, known to modulate TGFβ binding in target cells. We have previously found that betaglycan null murine testes at 12.5-13.5 dpc display poorly delineated seminiferous cords and disrupted Leydig cell development (1). Both TGFβs and inhibins are expressed by the fetal testis and it is currently unclear which regulate its development. We tested the hypothesis that loss of betaglycan compromises the functions of TGFβ2 in the differentiating fetal testis as TGFβ2 is known to bind poorly to its type II receptor in the absence of betaglycan. We tested the effect of TGFβ2 on betaglycan wildtype and null foetal gonad/mesonephros complexes using hanging drop or agar block culture methods. From each embryo, one gonad acted as a control; the other was treated. Gonads were cultured in the presence or absence of TGFβ2 (2.5-5 ng/mL) for 48 hours (n =3 pairs). In both culture methods, development in the absence of exogenous growth factor recapitulated normal cord development in wildtype testis and the disrupted cord phenotype in null testes. TGFβ2-treated cultures, 13.5 dpc wildtype mouse testes displayed a 14-35% reduction in total area compared to untreated cultures. Null testes exhibited significantly smaller reductions in gonadal area (2-13%; P < 0.01), indicating that betaglycan null testes exhibit reduced sensitivity to TGFβ2-mediated growth inhibition. However, preliminary observations suggest that TGFβ2 treatment partly rescued cord formation in two of three betaglycan knockout testes in vitro, with testis morphology confirmed by laminin and AMH immunostaining. These data support the notion that TGFβ2 acts via betaglycan to regulate cord development during foetal testis development. Supported by the New Investigator NHMRC (AUS) grant #550915 to MS, JKF Fellowship (#441101, #550915, #338516;#241000) and Victorian Government infrastructure funds. (1) Sarraj et al., 2010. Biol Reprod; 82(1): 153–62.

Estrogen signaling in the regulation of female reproductive functions

Estrogens influence fertility and infertility in animals. This chapter reviews the use of estrogen as a contraceptive through the regulation of its production and action. It is concluded that the use of specific agonists and antagonists of estrogen action that avoid the global and unwanted side effects of estrogen offers new potential methods of contraception.

132. ACTIVIN A HAS A STIMULATORY EFFECT IN VITRO ON EARLY FOLLICLE DEVELOPMENT IN RAT OVARIES

Activins are dimers of inhibin β subunits and are growth and differentiation factors belonging to the transforming growth factor-β (TGF-β) superfamily (1). Both βA and βB subunits are highly expressed in rat granulosa cells, while theca cells express little or no β subunit mRNAs (2). Oocytes lack expression of either subunit (3, 4). Activin is suggested to facilitate the responsiveness of granulosa cells to FSH (5). We hypothesized that activin, with or without FSH, could enhance the transition from the primordial to later preantral stages of follicle development. In two independent experiments, day 4 rat ovaries (n = 3 from different rats per treatment) were randomly assigned and cultured (6, 7) for 10 days in DMEM/Hams F-12 media with either no additives, FSH (100 ng/mL), activin A (50 ng/mL), or both. Day 4 fresh ovaries were also used as controls. Media and treatments were refreshed every alternate day. Ovaries were fixed andsectioned, or placed into Ultraspec for RNA extraction and real-time PCR analysis. Follicle numbers were counted as described previously (7). The proportion of atretic follicles (TUNEL staining) was determined in 3 randomly selected sections per ovary. Primordial follicles in all treatment groups were approximately 20% of those in Day 4 fresh ovaries. Primary follicles increased significantly (P < 0.05) only in the combined treatment group, where preantral follicles increased significantly (P < 0.0001) only when treated with activin A alone. Activin A alone decreased the proportion of atretic follicles in the primary and preantral classes, where the combined treatment increased the proportion of atretic preantral follicles. Real-time analysis revealed that expression levels of follistatin, FSH receptor and activin βA and βB subunits were all expressed at significantly higher levels in the Activin A-only treated group (P < 0.05). In summary, there was no effect on primordial follicle activation by any treatment. Activin alone had a stimulatory effect in vitro on subsequent folliculogenesis, but in the presence of FSH its effect was counteracted shown by an increase in atresia. Reasons for an increase in atretic preantral follicles in the combined treatment group are unclear. These studies support a stimulatory role for activin A in early follicle development and confirm the in vivo effects of activin on folliculogenesis (4). NHMRC program grant # 494802 and Fellowship (# 441101) provided financial support. (1) Vale W et al. 1986. Nature 321: 776–779.(2) Meunier H et al. 1988. Proc Natl Acad Sci USA 85: 547–251.(3) Roberts V et al. 1993. Journal of Clinical Endocrinology & Metabolism 7: 1402–1410.(4) Sidis Y et al. 1998. Biology of Reproduction 59(4): 807–812.(5) Drummond A et al. 2002. Endocrinology 143 (4): 1423–1433.(6) Nilsson E et al. 2001. Molecular and Cellular Endocrinology 182 (2): 145–155.(7) Rosairo D et al. 2008. Reproduction 136: 799–809.

127. PUMA MEDIATES GERM CELL DEATH DURING OVARIAN DEVELOPMENT AND DETERMINES INITIAL PRIMORDIAL FOLLICLE NUMBER IN MICE

The proteins that control the number of primordial follicles initially established within the ovary are largely unknown. Here we investigated the hypothesis that PUMA, a pro-apoptotic protein belonging to the Bcl-2 family, regulates germ cell death during ovarian development and thereby determines the number of primordial follicles that make up the ovarian reserve. Ovaries were obtained from embryonic day 17.5 (E17.5) and post-natal day 10 (PN10) wild-type (wt) and puma–/– mice and subjected to morphological, molecular and stereological characterisation (n = 3-6 mice/genotype/age). At E17.5, ovaries were densely populated with germ cells and early meiotic oocytes. Immunostaining for MVH and PCNA confirmed the identity of germ cells and proliferating germ cells, respectively. Pyknotic nuclei and TUNEL positive germ cells were rarely detected, suggesting that cell death was uncommon at this age. At PN10, primordial follicle assembly was complete for both genotypes, as confirmed morphologically and by immunostaining for oocyte markers GCNA and MSY2. The number of germ cells in E17.5 wt and puma–/– ovaries was comparable (p=0.81, See Table 1). However, PN10 puma–/– ovaries contained significantly more primordial follicles than wt ovaries (P < 0.001, See Table 1), revealing an over-endowment of primordial follicles in the absence of PUMA. These data show that PUMA regulates the developmentally programmed death of germ cells between E17.5 and PN10 in the mouse and thereby determines the number of primordial follicles that make up the initial ovarian reserve. This work was supported by the NHMRC (Program Grants #494802 and #257502, Fellowships JKF (#441101), KJH (#494836), CLS (#406675), AS (#461299)); the Leukemia and Lymphoma Society (New York; SCOR grant#7015), the National Cancer Institute (NIH, US; CA80188 and CA43540) and Victorian Government Infrastructure Funds.

A randomized controlled trial of treatment options for troublesome uterine bleeding in Implanon users

BACKGROUND

Pilot data have indicated that both doxycycline alone and mifepristone combined with ethinyl estradiol (EE) are effective in stopping episodes of bleeding in Implanon users with troublesome bleeding. We compared four treatments against a placebo in Implanon users and tested whether repeated treatment improved subsequent bleeding patterns.

METHOD

Implanon users aged 18-45 years were randomized to treatment with (i) mifepristone 25 mg given twice on day 1 followed by 4 days of EE 20 microg; (ii) doxycycline 100 mg twice daily for 5 days; (iii) mifepristone 25 mg given twice on day 1 plus doxycycline 100 mg twice daily for 5 days; (iv) doxycycline 100 mg twice daily with EE 20 microg daily; and (v) placebo twice daily for 5 days. The primary end-point was the number of days of bleeding/spotting immediately following initiation of the first 5-day course of each therapy, compared with placebo.

RESULTS

There were 204 women assigned to treatment. Mifepristone in combination with either EE or doxycycline was significantly more effective in stopping an episode of bleeding (mean 4.0 days (CI 3.5-4.6) and 4.4 days (CI 3.8-5.2), respectively) than doxycycline alone or in combination with EE, or placebo (6.4 days (CI 4.4-9.2), 6.4 days (CI 4.8-8.6) and 6.4 days (CL 5.1-8.0), respectively).

CONCLUSION

Mifepristone combined with either EE or doxycycline was significantly more effective than placebo in terminating an episode of bleeding in Implanon users. However there was no improvement in subsequent bleeding patterns.

TRIAL REGISTRATION NUMBER

ACTR # 012605000206628.

122. REGULATION OF GDF-9 AND GDF-9B BY FSH IN PREANTRAL FOLLICLE CULTURES

GDF-9 and -9B (BMP-15) are oocyte-derived members of the TGF-β superfamily. In the mouse ovary, the absence of GDF-9 leads to an arrest of follicle development at the primary/preantral stage. As a result GDF9 deficient mice are infertile1 because follicle development does not reach a stage where ovulation and oocyte release can occur. In contrast, GDF-9B knockout mice are subfertile2. GDF-9 was shown to act via TGFβRI and BMPRII and GDF-9B via BMPRIB and BMPRII. We have much to learn about what regulates the production of GDF-9, GDF-9B and the expression of its receptors. These studies investigated whether FSH, an important mediator of folliculogenesis, plays a role in this regulation. Preantral follicles (110–135 µm in diameter) were isolated from 18 day old C57BL/6 mice using fine needles. Follicles were cultured (30–35 per well) for 7 days with varying doses of FSH (0–100ng/ml). RNA was extracted, reverse transcribed and real time PCR was carried out with primer sets for GDF-9, GDF-9B, TGFβRI, BMPRII and GAPDH. Immunohistochemistry was conducted on sections of formalin-fixed 18 day old mouse ovary using antisera directed at TGFβRI and BMPRII. GDF-9 and GDF-9B mRNAs were downregulated by FSH treatment (compared to untreated control). There was no effect of FSH on the expression of either receptor. TGFβRI and BMPRII receptor proteins were localised to the cytoplasm of oocytes and granulosa cells in 18 day old mouse ovary. Both were mostly localised to secondary follicles, lighter TGFβRI staining was found in less mature follicles. Receptors for GDF9 signalling were both present consistent with direct effects of GDF9 on ovarian function. GDF9B might also have an effect although it remains to be seen if the type 1 receptor is localised to the mouse ovary. Further studies are required to investigate receptor regulation.

123. ACTIVIN A AND OVARIAN FOLLICLE DEVELOPMENT

A significant developmental stage in ovarian folliculogenesis is the acquisition of gonadotropin sensitivity by ovarian follicles. Activin has previously been suggested to be involved in the responsiveness of granulosa cells to FSH (1). Therefore, the role of activin was investigated using a ‘physiological’ culture system to determine if pathways exist to transduce activin signals within the postnatal rat ovary. Organ cultures with day 4 whole ovaries were employed in order to assess the potential impact of Activin A on follicle growth and transition from the primordial through to the primary and later preantral stages of development. Ovaries were isolated and cultured for 10 days with the addition of supplemented DMEM/Hams F-12 media (2)and either FSH (100ng/ml), Activin A (50ng/ml), or a combination of the two. Media and treatments were refreshed every alternate day. At the end of the culture period, ovaries were fixed and sectioned, or placed immediately into Ultraspec for RNA extraction for future real-time PCR. Sections were used for morphological assessment and ovarian follicle counting of primordial, primary and preantral follicles. An evaluation of atresia by the detection of apoptotic cells was undertaken using terminal deoxynucleotidyl transferase (TdT) mediated dUTP-biotin nick-end labeling (TUNEL). Primary follicle numbers increased significantly (P<0.05) in the combined treatment group whereas, preantral follicle numbers increased significantly (P<0.0001) when treated with Activin A alone. This is consistent with a morphological appraisal of atresia where a decrease in atresia was found in primordial and primary follicles, supporting the primary follicle development data and Activin A treatment alone resulted in more healthy primary and preantral follicles than atretic ones. Therefore, a stimulatory role for Activin A both in the presence of FSH (primary follicle development) or alone (preantral follicle development) has resulted in more follicles making the transition from the primordial to primary stages, as well as to the later preantral stages.

513. LOSS OF BETAGLYCAN DISRUPTS SOMATIC CELL DIFFERENTIATION IN THE FETAL MOUSE OVARY

Betaglycan (TGFBR3) is an accessory receptor that modulates the activities of members of the TGF-beta superfamily of growth factors which regulate many aspects of reproductive biology. We reported the presence of betaglycan on somatic and germ cells in fetal murine ovary from 12.5 dpc [1]. However, the role of this receptor in early ovarian development is poorly understood. We hypothesised that, given its expression pattern, betaglycan could serve as a TGFb accessory receptor on both oogonia and somatic cells during early ovarian development. In the current study, we examined the Tgfbr3 (betaglycan) null and wildtype ovary from 11.5–14.5 dpc. During this window of development, no overt morphological phenotype was detected, and cell proliferation (PCNA immunostaining) and apoptosis (active caspase 3 immunostaining) were unchanged in the null ovary. To determine whether somatic and/or germ cell markers were altered in the absence of betaglycan, quantitative real time PCR analysis was conducted using total RNA derived from 11.5–14.5 dpc betaglycan wildtype, heterozygous, and null ovaries (n=3 at each age/genotype). From 12.5 dpc, genes associated with the differentiation of the female somatic lineages Wnt4, Fst, Bmp2 were significantly decreased in the null ovary by 30%–50% (P<0.05) while germ cell markers (Oct4, Mvh) showed no significant changes compared to wildtype ovary. Genes associated with the testis-differentiation pathway (e.g. Sox9, Cyp11a1, Cyp17a1, Hsd3b, Insl3, Dhh) were not aberrantly expressed in betaglycan null or heterozygous ovary, with expression levels very low to undetectable. Collectively, these data suggest that while betaglycan does not appear to play a key role in establishing the structure of the ovary, loss of this receptor results in a disruption to the differentiation of ovarian somatic cells.

The nature and role of pregnancy-associated antigens and the endocrinology of early pregnancy in the ewe

Depite descriptions of many of the physiological events of early pregnancy in the ewe, the way in which the immunological and endocrine adjustments are brought about is not well understood. Obviously, specific effects--for example, maintenance of the corpus luteum--are brought about by the presence of a conceptus in the uterus. This has led to a search for substances produced by the conceptus or induced by the presence of the conceptus in the uterus which could be involved in establishing pregnancy. This paper describes the presence in sheep of substances associated with pregnancy and discusses the origin and characterization of these substances and their role in ovine pregnancy.

209. The absence of betaglycan affects Sox9 m RNA expression at the time of sex determination in a mouse model

Betaglycan is a co-receptor that binds both TGF-β and inhibin, and thereby acts as a modulator of the activities of multiple members of the TGF-β superfamily. We have previously shown that the murine betaglycan gene is expressed in somatic cells within the interstitium of the fetal testis from 12.5 dpc-16.5 dpc. Betaglycan protein was predominantly localised to the interstitial cells surrounding the developing seminiferous cords which stained positive for Cyp11a (p450 Scc), a Leydig cell marker. In order to determine the impact of this receptor on fetal Leydig cell biology, RNA was extracted from two independently collected sets of betaglycan knockout and wildtype male and female gonads at 12.5 dpc and 13.5 dpc (n = 4 gonad pairs/set), and quantitative real time PCR was performed to determine changes in the expression levels of key genes involved in fetal Leydig cell differentiation and function. This analysis revealed that the levels of mRNA expression of SF1, Cyp11a and Cyp17a1 were downregulated between 12.5–13.5 dpc in the betaglycan knockout embryos compared with wildtype embryos immediately after the time of sex determination. Interestingly, the expression level of the key Sertoli cell marker SRY-(sex determining region Y)-box 9 (Sox9) was transiently decreased at 12.5 dpc by 50% in the knockout testis in comparison with that of the wildtype testis. No significant change was found one day later at 13.5 dpc. Our data show that betaglycan is predominantly expressed in the fetal Leydig cells of the murine testis and that the presence of this receptor is required for normal fetal Leydig cell differentiation. Furthermore, the transient downregulation of Sox9 expression in null testis suggests that Sertoli cell differentiation may also be affected in betaglycan knockout mice, and that this defect may precede the defect in Leydig cell development. Supported by: the NHMRC Australia (RegKeys 338516; 241000).

266. Loss of betaglycan expression contributes to malignant properties of human granulosa tumour cells

Betaglycan is a type III TGF-β receptor that binds to both inhibin and TGF-β with high affinity and determines cellular sensitivity to these ligands. Previous studies have suggested that betaglycan acts as a tumour suppressor in certain human epithelial cancers. However, the roles of betaglycan in ovarian granulosa cell tumours (GCTs) are poorly understood. The objective of this study was to determine whether human GCTs exhibit betaglycan expression, and if so, what impact this receptor has on tumour biology. Real-time PCR was used to quantify betaglycan transcripts in human GCTs (n = 18) and normal premenopausal ovaries (n = 11). This analysis established that GCTs exhibited a significant 2-fold reduction in mean betaglycan mRNA levels as compared with the normal ovary (P < 0.05). Similarly, two human GCT cell lines, the KGN and COV434, exhibited low betaglycan expression and poor responsiveness to TGF-β and inhibin in luciferase reporter assays. Stable transfection of GCT cell lines with a wildtype betaglycan (WT-BG) expression plasmid conveyed ligand responsiveness. FACS analysis was used to examine cell cycle progression and cell death in the GCT cell lines. This analysis revealed that WT-BG had no effect on the number of cells cycling or undergoing apoptosis. However, WT-BG significantly increased the adhesion of COV434 (P < 0.05) and KGN (P < 0.0001) cells to collagen IV and fibronectin, decreased cellular invasion through Matrigel COV434 (50%) and KGN (75%), and inhibited wound healing COV434 (70%) and KGN (80%). Collectively, the data establish that betaglycan is an important regulator of granulosa cell biology and suggest that a deficiency in betaglycan contributes to the pathogenesis of granulosa cell cancer. The work further suggests a role for betaglycan in the prevention of tumour invasion, possibly by increasing the adhesion of granulosa cells to matrix components. Supported by: the NHMRC of Australia (RegKeys 338516; 241000; 441101; 388904).

270. TGF-β and ovarian follicle development

The role TGF-β plays in ovarian follicular growth and differentiation was investigated using a ‘physiological' culture system. TGF- β ligand and receptors are present in the rat ovary from 4 days after birth. Therefore we established organ cultures with these ovaries in order to assess the potential impact of TGF- β1 on follicle growth and transition from the primordial through to the primary and preantral stages of development. Whole ovaries were isolated and cultured for 10 days on floating filters with the addition of supplemented DMEM/Hams F-12 media and either FSH (100ng/mL), TGF- β1 (10ng/mL), or a combination of the two. Media as well as treatments were refreshed every second day. At the end of the culture period, ovaries were fixed in 10% formalin, embedded in paraffin and sectioned at 5µm. Sections were used for morphological assessment and ovarian follicle counting with three serial sections mounted/slide and every alternate slide used for counting of primordial, primary and preantral follicles. An evaluation of atresia by the detection of apoptotic cells was undertaken using terminal deoxynucleotidyl transferase (TdT) mediated dUTP-biotin nick-end labelling (TUNEL) via the ApopTag® Peroxidase in situ apoptosis detection kit. Results gathered from this study show preantral follicle numbers declined significantly when treated with the combination of FSH and TGF- β1, consistent with our morphological appraisal of atresia where the combined treatment appeared to produce more apoptotic follicles than healthy follicles, suggesting an increase in atretic primary and preantral follicles. These preliminary findings suggest an inhibitory role for TGF- β1 in the presence of FSH, resulting in fewer follicles making the transition from the primary to the preantral stage. Further studies are required to test the effects of other TGF-β superfamily members on follicle transition in vitro. Supported by the NHMRC of Australia (Regkeys 241000, 441101, 465415, 198705)

255. Hormonal manipulation on the phenotype of ArKO female mice

Gonadotrophins and steroid hormones are vital in controlling the cyclical pattern of ovarian follicular development essential for fertility. Previous studies have shown that ArKO (aromatase knockout) female mice are infertile due to the absence of oestrogen, elevated levels of circulating gonadotrophins and testosterone and folliculogenic disruption. Therefore, the aim of this study was to determine the effects of E2 (oestradiol-17β) replacement, Acyline (GnRH antagonist) and Flutamide (anti-androgen) treatment on ArKO female mice. WT and ArKO female mice (C57B6/J129; 16 weeks old; n = 6–8/grp) were assigned into three main groups: group 1 - received either E2 (0.05 mg) pellet or placebo, group 2 - received either a single s.c. injection of acyline (1.5 mg/kg/week) or placebo and group 3 – received either flutamide (25 mg) pellet or placebo for 3 weeks. Mice were subjected to daily vaginal smears. The ovaries and uterine horns were collected and weighed. One ovary and the uterine horns were fixed in formalin for histological assessment, while the other ovary was snap frozen in Ultraspec solution for RNA isolation and gene expression studies. Serum was collected for hormone measurements. All female ArKO mice exhibited an abnormal cycle that alternated between diestrus and early oestrus. E2 replacement restored the oestrus cycle in ArKO female mice but acyline and flutamide treatment did not. Histologically, hemorrhagic cystic follicles were present in all placebo, acyline and flutamide treated ArKO ovaries, however, E2 replacement improved the ovarian and uterine phenotypes. E2 replacement and acyline treatment also led to a decrease in serum gonadotropin levels in ArKO mice. In summary, E2 replacement could reverse the abnormal reproductive phenotype of the ArKO female mice. This study suggests that the reproductive phenotype of the ArKO female mouse is due to the direct effect of oestrogen and not due to the elevated circulating levels of gonadotrophins and testosterone. Supported by NH&MRC (Regkeys 241000, 338510 and 198705)

267. A role for transforming growth factor-β 1 (TGF-β1) during the establishment of folliculogenesis

A group of structurally related proteins, known as the transforming growth factor-β (TGF- β) superfamily, have been implicated in the local regulation of ovarian function. It is unclear what role TGF-β1–3 plays in folliculogenesis during the period after birth in the rat. We investigated whether the TGF-β ligands and their receptors were present during this period of development and the effects of TGF-β1 on granulosa cell function (proliferation, apoptosis, steroidogenesis). Ovaries from rats 4, 8 and 12 days of age were isolated and RNA extracted and reverse transcribed for real-time PCR. The expression of the TGF-β ligands and TGFβRI and TGFβRII were measured. Granulosa cells isolated from DES treated immature rats were treated with FSH (100ng/mL) and TGF-β1 (1 or 10ng/mL) for 2hr, n = 4 replicates. The RNA was extracted and prepared for RT–PCR. The expression of cyclin D2, FKHR, SCC, 3βHSD and StAR were measured. TGFβRI and TGFβRII proteins were localised to postnatal rat ovary by immunohistochemistry. TGF-β1–3, TGFβRI and TGFβRII were present in rat ovaries as early as 4 days after birth. Expression of TGF-β1 mRNA increased 2-fold between day 4 and 12. TGF-β2 and TGF-β3 mRNAs declined between day 4 and 8 and remained low at day 12. The type I and II TGF-β receptors were differentially regulated with TGFβRI expression high at day 4, declining at day 8. In contrast, TGFβRII appeared to be ubiquitously expressed. Cyclin D2 mRNA expression was enhanced in the presence of both TGF-β1 and FSH, whereas FKHR mRNA expression declined. TGF-β1 had no impact on the steroidogenic mRNAs. TGFβRI and TGFβRII proteins were localised to the cytoplasm of oocytes, granulosa cells and theca cells. These studies indicate that TGF-β1 can exert effects on ovarian folliculogenesis as it is established during the postnatal period. Proliferation and apoptosis appear to be targets of TGF-β1 action. Supported by the NHMRC of Australia (Regkeys 241000, 198705, 441101 & 465415)

Human embryo: a biological definition

This paper defines a human embryo from a biological standpoint that takes into account emerging technologies in reproductive science. The paper does not consider legal, moral, religious or social views. As the definition of a human embryo must reflect the multifactorial processes of development, an approach has been adopted which combines recognition of observed events with potential for further development. This acknowledges that fertilization and development are not static processes, and as such embryo status can only be defined by observation of specific markers. The following biological definition of 'human embryo' is proposed. A human embryo is a discrete entity that has arisen from either: the first mitotic division when fertilization of a human oocyte by a human sperm is complete or any other process that initiates organized development of a biological entity with a human nuclear genome or altered human nuclear genome that has the potential to develop up to, or beyond, the stage at which the primitive streak appears, and has not yet reached 8 weeks of development since the first mitotic division.

Quantification of healthy follicles in the neonatal and adult mouse ovary: evidence for maintenance of primordial follicle supply

Proliferation and partial meiotic maturation of germ cells in fetal ovaries is believed to establish a finite, non-renewable pool of primordial follicles at birth. The supply of primordial follicles in postnatal life should be depleted during folliculogenesis, either undergoing atresia or surviving to ovulation. Recent studies of mouse ovaries propose that intra- and extraovarian germline stem cells replenish oocytes and form new primordial follicles. We quantified all healthy follicles in C57BL/6 mouse ovaries from day 1 to 200 using unbiased stereological methods, immunolabelling of oocyte meiosis (germ cell nuclear antigen (GCNA)) and ovarian cell proliferation (proliferating cell nuclear antigen (PCNA)) and electronmicroscopy. Day 1 ovaries contained 7924+/-1564 (s.e.m.) oocytes or primordial follicles, declining on day 7 to 1987+/-203, with 200-800 oocytes ejected from individual ovaries on that day and day 12. Discarded oocytes and those subjacent to the surface epithelium were GCNA-positive indicating their incomplete meiotic maturation. From day 7 to 100 mean numbers of primordial follicles per ovary were not significantly depleted but declined at 200 days to 254+/-71. Mean numbers of all healthy follicles per ovary were not significantly different from day 7 to 100 (range 2332+/-349-3007+/-322). Primordial follicle oocytes were PCNA-negative. Occasional unidentified cells were PCNA-positive with mitotic figures observed in the cortex of day 1 and 12 ovaries. Although we found no evidence for ovarian germline stem cells, our data support the hypothesis of postnatal follicle renewal in postnatal and adult ovaries of C57BL/6 mice.

A pilot study to assess the effect of three short-term treatments on frequent and/or prolonged bleeding compared to placebo in women using Implanon

BACKGROUND

The major side-effect of progestogen-only contraception is disruption of menstrual bleeding patterns, which can lead to a high incidence of early discontinuation. The aim of this study was to compare three treatments with placebo on the duration and recurrence of frequent and/or prolonged bleeding in Implanon users.

METHOD

Women between the ages of 18 and 45 years, who had used Implanon for > or =3 months and were experiencing prolonged or frequent bleeding patterns, were recruited at four Australian sites. Subjects were randomized to treatment using computer-generated random number table if they met the World Health Organization criteria for prolonged and/or frequent bleeding in the previous 90 days [Belsey, E.M., Pinol, A.P.Y. and Taskforce on Long-Acting Systemic Agents for Fertility Regulation, World Health Organization (1997) Contraception 55,57-65]. Treatments were: (1) mifepristone 25 mg given twice on day 1 followed by 4 days of twice daily placebo; (2) mifepristone 25 mg given twice on day 1 followed by 4 days of ethinyl estradiol (EE) 20 microg in the morning and placebo at night; (3) doxycycline 100 mg twice daily for 5 days; and (4) placebo twice daily for 5 days. Analysis was by intention to treat. The primary endpoint was the number of days of bleeding and spotting immediately following initiation of the 5 day course of each active therapy compared with placebo.

RESULTS

A total of 179 women was assigned to treatment. Both mifepristone in combination with EE and doxycycline alone were significantly more effective in stopping an episode of bleeding {mean 4. 3 days [confidence interval (CI) 3.5-5.2], and 4.8 days (CI 3.9-5.8) respectively} than mifepristone alone or placebo [5.9 days (CI 4.8-7.2) and 7.5 days (CI 6.1-9.1) respectively]. No effect on subsequent bleeding patterns was observed in any treatment group.

CONCLUSION

Both mifepristone plus EE and doxycycline alone were significantly more effective than placebo in terminating an episode of bleeding in women with prolonged and/or frequent bleeding using Implanon. We believe that the observed reduction in the number of bleeding days by almost 50% compared to placebo in both the mifepristone combination group and the doxycycline group demonstrates a clinically significant improvement in bleeding patterns and that further trials are needed to compare different combinations of therapy as well as multiple dosing regimens in order to establish which is the most effective treatment option. The effect of repeat administration or combinations of these preparations on long-term bleeding patterns requires further investigation.

HtrA3, a serine protease possessing an IGF-binding domain, is selectively expressed at the maternal-fetal interface during placentation in the mouse

Hemochorial placentation involves highly regulated interactions between fetal- and maternal-derived cells. HtrA3, a novel serine protease containing an insulin-like growth factor (IGF) binding domain, was previously shown to increase during early pregnancy in the mouse uterus, being dramatically upregulated post-implantation. The present study examined the regulation of HtrA3 gene in the mouse uterus from post-implantation to late gestation. Both mRNA and protein of HtrA3 were localized specifically in the maternal decidua. In contrast, HtrA3 expression was below detection in trophoblasts, including the giant cells that are in direct contact with the decidua. This pattern persisted from the early stages of placentation to near term. The level of decidual HtrA3 mRNA and its protein gradually decreased as the placenta matured. In the decidua, only the maternal decidual cells, but not blood vessels or uterine NK cells that are present in large numbers, were positive for HtrA3. The specific localization of a protease possessing an IGF-binding domain at the maternal-fetal interface suggests that HtrA3 plays a critical role in mediating maternal decidual remodelling and maintenance, likely in association with the IGF system, in placental development and function.

259. Reproductive phenotype of the female aromatase overexpressing mouse

Aromatase, the product of the Cyp 19 gene, converts androgens to estrogens. The role of estrogens within the ovary has recently been revisited; using the aromatase knockout (ArKO) mouse, we investigated the effect of estrogen deficiency on ovarian function. We now have an aromatase overexpressing (AROM+) female mouse model with elevated levels of estrogens. These mice were fertile and bred with FVB/N wildtype (WT) males, the AROM+ male being infertile. In this study we characterised the reproductive phenotype of the female AROM+ mouse. 5 WT and 10 AROM+ mice, 22–27 weeks of age were used in the study. The mice were subject to vaginal smears and killed during estrus. The ovaries, uterine horns and gonadal fat were collected and weighed. One ovary and the uterine horns were fixed in formalin for histological assessment, while the other ovary was snap frozen in Ultraspec solution for RNA isolation and gene expression studies. Serum was collected for hormone measurements. All AROM+ mice exhibited an abnormal pattern of cycling that in general, alternated between estrus and post-estrus. AROM+ mice were significantly heavier than their WT counterparts (WT 35.28 ± 2.89 g v. AROM+ 43.38 ± 2.11 g, P < 0.05). Ovarian, uterine and gonadal fat pad weights were not significantly different between the 2 groups (ovary: WT 17.4 ± 1.14 mg v. AROM+ 17.9 ± 0.06 mg; uterine horns: WT 89.7 ± 11.40 mg v. AROM+ 92.1 ± 6.64 mg; gonadal fat pads: WT 2.47 ± 0.62 g v. AROM+ 3.46±0.26 g). Histological, gene expression and hormone analyses are in progress. Our preliminary analyses indicated no significant effect of excess estrogen on ovarian, uterine and gonadal fat pad weights, despite the AROM+ mice being heavier. It remains to be determined as to whether the ovaries and uterine horns are histologically normal. Supported by the NHMRC (Regkeys 241000, 338510, 198705)

118. Regulation of inhibin binding and action via betaglycan expression in mouse Leydig-like TM3 cells

The actions of inhibin and transforming growth factor (TGF)-β2 are enhanced when their respective target cells express the TGF-β/inhibin co-receptor, betaglycan. In the present studies, we investigated the effects of multiple members of the TGF-β superfamily on betaglycan expression, and examined the consequences of such regulation for inhibin binding, and inhibin and TGF-β actions in mouse Leydig-like TM3 cells. Isoforms of activin (A and B), TGF-β (1 and 2) and BMP (2, 6 and 7) each suppressed the level of betaglycan mRNA in TM3 cells to 43–46%, 26–39% and 50–71% of control, respectively, during overnight treatment. Subsequent inhibin A binding was suppressed to 72–77%, 35–36% and 66–70% of control, respectively, with IC50s of 0.07–0.7, 0.05–0.5 and 0.4–0.6 nM, respectively. The effects of inhibiting betaglycan expression by TM3 cells on their responses to inhibin and TGF-β2 were examined by transfecting cells with a promoter construct that contains three copies of the activin-responsive sequence of the GnRHR promoter (3XpGRAS-PRL-lux) either alone or in the presence of small (21 bp) duplex siRNAs corresponding to the betaglycan gene. Activin A (0.5 nM) stimulated 3XpGRAS-PRL-lux expression 3–4 fold over control in TM3 cells, and inhibin dose-dependently abolished this stimulation, with no interference from the control siRNA (against BF-1 forkhead-like protein). However, inhibin suppression of activin-stimulated activity was antagonized in cells co-transfected with betaglycan siRNA. TGF-β (1 and 2) stimulated 3XpGRAS-PRL-lux expression 5–8 fold over control, and the action of TGF-β2, but not TGF-β1, was attenuated by the betaglycan siRNA. In summary, activin, TGF-β and BMP isoforms inhibit betaglycan expression by Leydig-like TM3 cells, and inhibin A binding is commensurately reduced. The ‘knock-down’ of betaglycan expression by specific siRNA inhibits TM3 responses to inhibin and TGF-β2. Whether the inhibition of betaglycan expression by activin, TGF-β and BMP has similar consequences for inhibin and/or TGF-β2 action is yet to be determined. These studies raise the possibility that multiple members of the TGF-β superfamily participate in cross-talk via the inhibin/TGF-β co-receptor, betaglycan. Funded by the NH&MRC of Australia (RegKey 241000 & 198705).

218.FGF9 stimulates ovarian progesterone production

FGF9, a member of the fibroblast growth factor family (FGF), is known to be a male sex-determining factor involved in testicular cord formation (1). FGF9 knockout males are sex-reversed (2). However, nothing is known about FGF9's role in folliculogenesis because these mice die at birth (2). We previously reported the presence of FGF9 mRNA and protein in the immature rat ovary (3). In these studies we investigated: (1) the presence of FGF9 receptors (FGFR3) on granulosa cells (GC); and (2) the impact of FGF9 on GC progesterone production. GC isolated from 21 day old diethylstilboestrol (DES)-treated rats were cultured for either 2 hours (RNA) or 2 days (progesterone) in McCoys 5C with FGF9 (0.1-50ng/ml) � FSH (100ng/ml). Progesterone was measured in conditioned media by radioimmunoassay. RNA was extracted from the granulosa cells and reverse-transcribed for PCR. Specific primers for P450 side chain cleavage (SCC) amplified a 329�bp cDNA fragment. GAPDH was used for data normalisation. The FGF9 receptor FGFR3, was immunolocalised on formalin-fixed, paraffin-embedded sections of immature rat ovary. FGFR3 protein was localised only to GC of the ovary. Progesterone production by cultured GC was significantly elevated by FGF9, consistent with the presence of FGFR3. Relative to a maximally stimulating dose of FSH, FGF9 increased progesterone production 10- fold. In preliminary studies, FGF9 increased the expression of P450 SCC mRNA by cultured GC revealing a mechanism by which FGF9 increases progesterone production. These data suggest a role for FGF9 not just in testicular formation, but in the regulation of ovarian steroidogenesis. Supported by the NH&MRC of Australia (Regkey 241000 & 198705). (1) Cotinot et al. (2002) Semin. Reprod. Med. 20, 157. (2) Colvin et al. (2001) Cell 104, 875. (3) Drummond et al. (2003) SRB Abstract 90.

125. Differential regulation of inhibin binding via betaglycan expression in several mouse cell lines

Inhibin A, a member of the transforming growth factor (TGF)-β superfamily, binds to mouse adrenocortical (AC), Leydig (TM3) and Sertoli (TM4) cell lines with high affinity via at least eight membrane protein species, two of which are forms of betaglycan. Inhibin A has been proposed to inhibit the actions of activin and BMP by sequestering their type II receptors in high affinity complexes with betaglycan (1). We previously found that BMPs appear to counteract inhibin action in AC cells by selectively suppressing the expression of endogenous betaglycan, consequently reducing inhibin binding. In the present studies, we have examined how factors that stimulate betaglycan expression in other systems modify the binding of radiolabelled inhibin A at the surface of AC, TM3 and TM4 cells. AC, TM3 and TM4 cells were treated overnight with glucocorticoid, membrane-permeable cAMP analogue or retinoic acid, after which the levels of betaglycan mRNA, corrected for GAPDH content, were measured using real-time RT-PCR, and [125I]inhibin A binding was determined. Treatment of AC cell cultures with 8Br-cAMP (1�mM), glucocorticoid (RU28362, 100�nM) or retinoic acid (30�mM) increased betaglycan mRNA levels 120-150%, and increased subsequent inhibin A binding to 146���12, 132���13 and 125���18% of control (mean���SD, n = 6–12). The glucocorticoid and cAMP treatments also increased inhibin binding to TM3 and TM4 cells by similar amounts, but retinoic acid was less effective. Affinity labelled protein species of deduced sizes 115 and >170�kDa, consistent in size with betaglycan forms, were the primary target for stimulation by these agents, whereas species of 65 and 75�kDa were selectively increased by retinoic acid in the AC cells. In summary, glucocorticoids, retinoids and hormones that stimulate cAMP production may increase the expression of betaglycan in inhibin target cells, increase their binding of inhibin, and thereby promote inhibin action. These studies confirm that betaglycan is a primary determinant of inhibin binding and action. The protein species other than betaglycan that are selectively upregulated by retinoic acid in AC cells are yet to be identified. Funded by the NH&MRC of Australia (RegKey 241000 & 198705). (1) Wiater & Vale (2003) J. Biol. Chem. 278, 7934.

158. Effects of phytoestrogens on the ovarian and pituitary phenotypes of oestrogen deficient female aromatase knockout mice

Phytoestrogens can induce both estrogen agonistic and antagonistic effects, depending on the tissue, estrogen receptor content and endogenous levels of estrogen. Dietary phytoestrogens are promoted as alternatives to synthetic estrogens for hormone replacement therapy, however their effects on the reproductive axis have not been exhaustively studied in vivo. Female aromatase knockout mouse (ArKO) mice are estrogen-free, and anovulatory with a block in folliculogenesis, hemorrhagic cysts and development of Sertoli cells within their ovaries. We evaluated the ArKO mouse as a model to test the effects of phytoestrogen-supplemented diets on the reproductive organ weights, ovarian morphology, gonadotropin levels and the transcript levels of ovarian somatic cell and steroidogenic markers. The extent to which phytoestrogens either as soyfree or soymeal diet or genistein added to a soyfree diet, exert estrogenic effects varied with the type of phytoestrogen and the parameter being tested. The genistein diet significantly increased uterine and ovarian weights of ArKO compared to wildtype mice, whilst both the soy, and to a larger extent the genistein diet, improved ovarian morphology compared to the soyfree diet. Transformation to morphological Sertoli cells in ArKO mice was decreased by both phytoestrogen diets, whilst the gene expression of Sertoli cell markers was not affected. The soy diet increased both LH and FSH in both genotypes compared to animals on the soyfree diet. The genistein diet reduced FSH levels in ArKO mice, correlating with increased ovarian inhibin subunit expression. In conclusion, phytoestrogens are estrogenic in ArKO mice. Specifically, they can affect serum gonadotropin levels, and offset the development of Sertoli cells and hemorrhagic cysts within the ovaries, depending on the type of dietary phytoestrogen. Further studies are required to determine the effective doses and treatment regimes for phytoestrogens as endocrine modulators. Supported by NH&MRC Reg Key#198705.

202.Estrogen actions on follicle formation and early follicle development

Estradiol 17 beta (E2) effects late follicular development whilst primordial follicle formation and early activation are thought to be independent of E2. To test this hypothesis we compared numbers of primordial and primary follicles in wildtype and E2 deficient ArKO mice, and the immunohistochemical staining or mRNA expression of Mullerian inhibiting substance (MIS), Wilms tumour 1 (WT-1), and growth differentiation factor (GDF9), known to effect early follicular differentiation. Proliferating cell nuclear antigen (PCNA) staining was a marker of proliferative index. The effects of E2 replacement for 3 wk in 7 wk old ArKO and wildtype mice on these parameters were also tested. We used unbiased, assumption-free stereological methods for quantification of early follicular numbers in the mouse ovary (1). ArKO mice had reduced numbers of primordial and primary follicles compared to wildtype (63%, p<0.001 and 60%, p=0.062 of Wt respectively). This reduction was not corrected by E2 treatment, suggesting that E2 effects the initial formation or activation of primordial follicles. There was a significant increase in the diameters of the oocytes in primordial follicles of ArKO mice compared to wildtype. There were no differences in the immunostaining of MIS, WT-1 and PCNA in primordial and primary follicles between wildtype and ArKO mice. The only difference was as a consequence of Sertoli and Leydig cells in ovaries of ArKO mice. GDF9 mRNA expression was markedly increased in ArKO ovaries. E2 treatment restored the ovarian follicular morphology, and consequently the immunostaining patterns, but had no effect on early follicle numbers. In conclusion, E2 has a role in controlling the size of the oocyte and primordial follicle pools in mice. Supported by NH&MRC RegKey #241000 and 198705. (1) Britt and Myers (2004) Reproduction 127,:569–580.

Estrogen actions in the ovary revisited

Estrogens are synonymous with fertility and infertility in mammals. Our knowledge of the biological actions of estrogens, however, is incomplete. Three recent developments have thrown new light on the actions of estrogens in mammalian reproduction that will lead to a greater understanding of their functions. They are (a) the identification of a second estrogen receptor, called ERbeta, (b) the identification of ligand-specific ER coactivators and (c) mouse models with targeted disruption of the genes encoding both ER and the aromatase enzyme. These models provide for the first time animals which are either unable to respond to endogenous or exogenous estrogens (ER 'knockouts'), or can respond to exogenous estrogen but do not make endogenous estrogen (aromatase 'knockout' or ArKO). Furthermore, the ArKO mouse has provided a model to study the effects on the ovary of exogenous estrogens of plant and synthetic origin that are of clinical relevance. The data show that estrogens are essential for fertility but not for survival after birth or for the formation of the reproductive tract. This commentary focuses on the roles of estrogen in folliculogenesis and in the maintenance of the ovarian somatic cell phenotype in the mouse. We also hypothesize that the ERalpha and ERbeta may subserve the proliferative and differentiative actions of estrogen, respectively, within a follicle. In summary, estrogen is obligatory for normal folliculogenesis beyond the antral stage and for the maintenance of the female phenotype of the somatic cells within the ovaries. This clearly demonstrates a major role for sex steroids in somatic cell differentiation in the gonads of eutherian mammals and challenges the central paradigm that the ovary is the default gonad, arising due to the absence of testicular defining signals. Evidence is also provided for the plasticity of the adult female gonad. Understanding the mechanisms of estrogen actions will provide an insight into the regulation of reproductive disorders afflicting women today, notably ovarian dysfunction and the menopause.

A potential molecular mechanism for regulating pre-mRNA splicing of implantation-related genes through unique uterine expression of splicing factor SC35 in women and rhesus monkeys

Splicing factor SC35 is an essential component of the spliceosome, the cellular apparatus that removes introns from pre-mRNA to provide alternatively spliced isoforms. Many proteins associated with development of uterine receptivity and embryo implantation are present as isoforms, the tissue-specific expression of which may be regulated through alternative splicing. SC35 was identified as being increased at implantation sites during early pregnancy in mice. However, the present study has demonstrated that SC35 is present in human and rhesus monkey endometrium, that the protein is increased during the secretory phase of the oestrous cycle compared with the proliferative phase in both these primates and that it is present in a distinct pattern within the nucleus of both epithelial and stromal cells, as well as in cells of the vasculature. Both the intensity of immunoreactive protein and the proportion of cells that stain for SC35 alter with the phase of the oestrous cycle. A very precise expression pattern of SC35 (both protein and mRNA) was seen during early placentation in rhesus monkeys. At implantation sites between day 24 and day 35 of early pregnancy, SC35 was expressed strongly in cytotrophoblasts within the trophoblastic shell, in syncytiotrophoblast at the periphery of the cell column and in both cytotrophoblast and syncytiotrophoblast in the floating villi. In the adjacent maternal decidua, expression of SC35 was weak. These results indicate a role for SC35 in preparation of a receptive uterus, in the provision of secreted proteins to support blastocyst development and in trophoblast invasion.

The road to ovulation: the role of oestrogens

Oestrogens have been known for many years to have a direct influence on folliculogenesis. Oestradiol-17beta (E2) and its analogues have both proliferative and differentiative effects on somatic cells of follicles. Nevertheless, definitive proof of an obligatory role for oestrogen in folliculogenesis and elucidation of the mechanisms subserving its different actions in follicular cells remains elusive. Several recent developments permit a re-examination of the roles and actions of E2 in the follicle. They are: (i) the discovery of a second form of the oestrogen receptor, ERbeta; (ii) the advent of genetically modified mice with deletions in the ERalpha (alphaERKO) ERbeta (BERKO) and the double ER deletions (alphabetaERKO); and (iii) a mouse model of oestrogen deficiency (ArKO) by targeted disruption of the cyp 19 gene encoding the aromatase enzyme. Recent information derived from these models is reviewed to re-assess the roles and actions of oestrogens in follicular dynamics and the phenotypic differentiation of ovarian somatic cells in the ovary. The data demonstrate that oestrogen is obligatory for normal folliculogenesis and that the phenotype of the ovarian somatic cells depends on the steroid milieu. The ArKO mouse provides a model to test the roles of the respective ERs in proliferation and differentiation using specific agonists and antagonists, and to study regulation of the differentiation of ovarian and testicular somatic cells.

Recruitment and development of the follicle; the roles of the transforming growth factor-beta superfamily

Peripheral endocrine hormones and local paracrine and autocrine factors contribute, in a coordinated fashion, to the processes of recruitment, development or atresia, selection and ovulation of follicles. Among the local ovarian factors, there is growing evidence from genetic and experimental data that many members of the transforming growth factor (TGFbeta) superfamily have a biological role to play in folliculogenesis. These members include activin, inhibin, TGFbeta, BMP, GDF9 and perhaps MIS. In this review, we discuss the potential roles of the TGFbeta superfamily members, in particular activin, during folliculogenesis. Since the actions of these factors are determined by ligand availability, receptor expression and modulation of their signal transduction pathways, we also collate information on the expression of their signalling components in the follicle. We conclude that the TGFbeta superfamily signalling pathways, in particular activin's pathway, reside in the ovary. Furthermore, follistatin and beta-glycan-components of the accessory binding protein system that modifies activin action-are also present in follicles. In the post-natal rat ovary, the changes in receptor/Smad expression coincide with granulosa cell proliferation and antrum formation. We hypothesise that these pathway components are expressed in a temporal and cell-specific manner to meet the changing demands of cells during follicular development. The analysis of the components of the signal transduction pathways of the TGFbeta family members in populations of defined follicles and the identification of activated pathways in individually stimulated follicles should help clarify the roles of the TGFbeta members in folliculogenesis.

Genes involved in implantation

The endometrium is normally a hostile environment for an embryo, except for a short phase in each reproductive cycle known as the 'window of receptivity'. The precise molecular events involved in this transformation are not well understood. Application of state-of-the-art techniques of the 1990s has identified some of the genes involved, which are reviewed here. Mice with a null mutation in either the gene for leukemia inhibitory factor or the interleukin-11 receptor alpha chain are infertile, owing in both cases to a failure of embryo implantation. Both of these genes are expressed in the human endometrium with patterns suggesting a role in human fertility. The technique of RNA differential display has been applied to a comparison of the expression of genes at implantation sites v. inter-implantation sites in the mouse uterus on the first day of implantation, and has defined additional genes whose products may be important for this process. Among these are the calcium-binding protein D9K, the monoclonal non-specific suppressor factor beta, and the splicing factor SC35. The major challenge is to determine whether manipulation of such genes can increase or decrease endometrial receptivity in humans.

The ovarian phenotype of the aromatase knockout (ArKO) mouse

Targeted disruption of exon 9 of the cyp19 gene gives rise to a non-functional aromatase enzyme incapable of converting androgens to oestrogens. The aromatase knockout (ArKO) mouse is, thus, characterised by a dysfunctional pituitary-gonadal axis, which manifests in non-detectable levels of oestrogen in serum. These mice also exhibit elevated levels of circulating gonadotrophins (luteinising hormone (LH) and follicle stimulating hormone (FSH)) and testosterone. The ArKO mouse is infertile due to folliculogenic disruption and a failure to ovulate. The age-dependent ovarian phenotype revealed a block in follicular development at the antral stage and a complete absence of corpora lutea. By 21-23 weeks of age haemorrhagic cystic follicles were present and by 1 year there were abnormal follicles, an absence of secondary and antral follicles and atretic primary follicles. Interstitial tissue remodelling was extensive and exemplified by an increase in collagen deposition and an influx of macrophages, coincident with the loss of follicles. In mice, maintained on a soy-free and, thus, phytoestrogen-free diet, the ovarian phenotype was accelerated and exacerbated. In conclusion, the ovarian phenotype of the ArKO mouse can be attributed to the altered hormonal environment brought about by the absence of aromatase and the failure of androgens to be converted to oestrogens in the presence of elevated gonadotropins.

Kallikrein gene expression in the gonadotrophin-stimulated rat ovary

The kallikreins (KLKs) are a highly conserved multi-gene family of serine proteases that are expressed in a wide variety of tissues and act on a diverse range of substrates. KLK-like enzyme activity has variously been reported to increase or decrease during the period leading up to ovulation in the equine chorionic gonadotrophin (eCG)primed, human chorionic gonadotrophin (hCG)-stimulated immature rat ovary. These earlier studies, which used biochemical assays to detect enzyme activity, lacked the specificity and sensitivity necessary to characterise conclusively the activity of the individual KLK gene family members. In this study, we have used a gene-specific RT-PCR/Southern hybridisation strategy to delineate the expression patterns of six of the individual KLK genes expressed in the rat ovary (rKLK1-3 and rKLK7-9). We have identified three broad patterns of expression in the eCG/hCG-stimulated ovary in which there is either a post-eCG increase/pre-ovulatory decrease in rKLK expression (rKLK1, rKLK3), a peri-ovulatory decrease in expression (rKLK2, rKLK8) or a relatively unchanged pattern of expression (rKLK7, rKLK9). In addition to clarifying the earlier biochemical studies, these findings support a differential role for the individual KLKs in the ovulatory process.

Production and actions of inhibin and activin during folliculogenesis in the rat

Evidence to enhance the premise that inhibin and activin are local regulators of ovarian folliculogenesis is presented in this review. Granulosa cells (GC) have been identified as the source of inhibin/activin in the ovary on the basis of mRNA and protein localisation and the measurement of the inhibin forms in GC conditioned media. Expression of the subunit mRNAs changed with follicular development, being maximal in the ovaries of 8-day-old rats, where secondary follicles predominate. The expression of beta subunit mRNAs by GC isolated from diethylstilboestrol (DES)-treated immature rats, was reduced in the absence of any change in alpha subunit mRNA expression. Dimeric inhibin-A, -B and free alpha subunit were produced by ovarian cell cultures prepared from 4- to 12-day-old rats. Inhibin-A production by these cultures was responsive to FSH and TGF-beta, with preantral follicles of day 8 ovaries exerting effects so profound that the inhibin A/alpha subunit ratio increased, most likely due to a stimulation of beta(A) subunit production. In contrast, inhibin-B was not stimulated by TGF-beta until day 8 and FSH until day 12. Fractionation of GC conditioned media revealed a prominence of free alpha subunit and inhibin-A, but little inhibin-B, suggesting that inhibin-B production declines with follicular development. Activin receptor types I and II, Smads 1-8 and betaglycan (beta-glycan) mRNAs were present in the rat ovary and showed distinct patterns of expression between postnatal days 4 and 12. Oocytes and GC localised activin receptor, Smad and beta-glycan proteins, with beta-glycan also present in theca cells (TC). These data indicate that activin/TGF-beta signalling machinery and factors which influence these pathways, are present in the postnatal rat ovary. Our hypothesis that inhibin and activin play important and changing autocrine/paracrine roles in the growth and differentiation of follicles, including the oocyte, has been supported by these studies.

Inhibin binding sites and proteins in pituitary, gonadal, adrenal and bone cells

Activin signals via complexes of type I (50-55 kDa) and II (70-75 kDa) activin receptors, but the mechanism of inhibin action is unclear. Proposed models range from an anti-activin action at the type II activin receptor to independent actions involving putative inhibin receptors. Two membrane-embedded proteoglycans, betaglycan and p120, have recently been implicated in inhibin binding, but neither appears to be a signalling receptor. The present studies on primary cultures of rat pituitary and adrenal cells, and several murine and human cell lines were undertaken to characterise inhibin binding to its physiological targets. High affinity binding of inhibin to the primary cultures and several of the cell lines, like that previously described for ovine pituitary cells, was saturable and reversible. Scatchard analysis revealed two classes of binding sites (K(d) of 40-400 and 500-5000 pM, respectively). Affinity labelling identified [125I]inhibin binding proteins with apparent molecular weights of 41, 74, 114 and >170 kDa in all cell types that displayed high affinity, high capacity binding of inhibin. Additional labelling of a 124 kDa species was evident in gonadal TM3 and TM4 cell lines. In several cases, activin (> or =20 nM) competed poorly or not at all for binding to these proteins. The 74, 114 and >170 kDa inhibin binding proteins in TM3 and TM4 cells were immunoprecipitated by an anti-betaglycan antiserum. These three proteins correspond in size to the activin receptor type II and the core protein and glycosylated forms of betaglycan, respectively, that have been proposed to mediate anti-activin actions of inhibin, but the identity of the 74 kDa species is yet to be confirmed. Studies of [125I]inhibin binding kinetics and competition for affinity labelling of individual binding proteins in several cell lines suggest these three species and the 41 and 124 kDa proteins form a high affinity inhibin binding complex. In summary, common patterns of inhibin binding and affinity labelling were observed in inhibin target cells. Novel inhibin binding proteins of around 41 and 124 kDa were implicated in the high affinity binding of inhibin to cells from several sources.

Roles of activin and its signal transduction mechanisms in reproductive tissues

Activins were identified initially as gonadal proteins having a stimulating effect on FSH production by the pituitary gland. Strong evidence has accumulated that activins are important regulating factors for many reproductive processes. Activin may have paracrine or autocrine roles rather than solely an endocrine action on FSH secretion. Activins together with their signalling molecules must be shown to be produced locally in a particular tissue to provide support for their paracrine or autocrine action in that tissue. The discovery of the activin receptors, the intracellular signalling mediators (Smads) and some transcription co-factors involved in activin responses has helped to unravel the activin-transforming growth factor beta signalling mechanism. However, few reports have clearly demonstrated the presence of all of the activin signalling molecules in reproductive tissues, despite the important roles of activin in these tissues. Several activin receptor types and Smad molecules have been identified, indicating either a redundancy in signalling molecules or different signalling pathways. At present, it is not clear which particular subset of these signalling molecules is important in reproductive processes. The aim of this review is to collate the information available on activin actions, as well as on the signalling molecules, to understand how activins may transduce their paracrine or autocrine signals in reproductive tissues.

Effect of immunization against the alpha N (alphaN) and alpha C (alphaC) peptides of the alpha43 subunit of inhibin on antral follicular growth and atresia and the patterns of gonadotrophin secretion in ewes

The aims of this study were to investigate the role of inhibin in the distribution of healthy and atretic antral follicles and the secretion patterns of gonadotrophins. Ewes were actively immunized against either alphaN or alphaC of the inhibin alpha subunit with a primary injection and three booster injections. The control ewes received adjuvant only. The ovaries were removed either before or at 24 h after hCG administration in a synchronized follicular phase 48 h after removal of intravaginal progesterone pessaries. Morphological observations were made on every fifth section of the complete ovary (one per ewe) stained with haematoxylin and eosin. The mean number of corpora lutea observed per ewe with corpora lutea was not significantly different in ewes immunized against alphaN (2.4; alphaN-immunized ewes) or alphaC (2.6; alphaC-immunized ewes), and control (2.4) ewes, although some corpora lutea appeared cystic in the immunized ovaries. Compared with luteal phase concentrations, mean basal FSH concentrations in the early follicular phase were significantly increased in the alphaC-immunized ewes, similar in alphaN-immunized ewes and reduced in control ewes. No differences were observed in any of the LH parameters. Before hCG treatment, healthy antral follicles > 1 mm in diameter were not observed in any of the 52 follicles in the aC-immunized ewes and were observed in one of 37 follicles from alphaN-immunized ewes compared with 19 of 28 follicles in control ewes (P < 0.0001). For healthy antral follicles < 1 mm in diameter, there were 72 of 85 follicles in the alphaC-immunized ewes, 79 of 81 follicles in the alphaN-immunized ewes and 81 of 82 follicles in the control ewes. Similar results were obtained in healthy antral follicles < 1 mm in diameter at 24 h after hCG administration. In contrast to the control ewes, no healthy preovulatory follicles (> 6 mm in diameter) were observed in alphaN- and alphaC-immunized ewes either before or 24 h after hCG administration. Two newly formed corpora lutea from alphaC-immunized ovaries contained retained oocytes compared with none in control and alphaN-immunized ovaries. In conclusion, immunization against alphaN and alphaC may result in disruption of the normal processes of antral follicular growth and maturation independent of the concentrations of FSH and LH.

Identification of specific inhibin A-binding proteins on mouse Leydig (TM3) and sertoli (TM4) cell lines

The binding of human inhibin A to cell surface binding proteins of mouse Leydig (TM3) and Sertoli (TM4) cell lines was investigated. Scatchard analysis identified two classes of inhibin A-binding sites on TM3 (K(d(1)) = 85 pM and 4,160 sites/cell; K(d(2)) = 520 pM and 12,500 sites/cell) and TM4 (K(d(1)) = 61 pM and 2,620 sites/cell; K(d(2)) = 520 pM and 10,400 sites/cell) cells. Compared with inhibin A, inhibin B only partially competed [(125)I]inhibin A binding (6-8%), whereas activin A competed weakly (<0.01%). Chemical cross-linking of [(125)I]inhibin A to both cell lines identified five [(125)I]inhibin A binding complexes with apparent molecular masses of 70, 95, 145, 155, and more than 200 kDa. Inhibin A displacement of [(125)I]inhibin A from each of these cross-linked species (ED(50) = 60-110 pM) closely resembled displacement from intact TM3 (ED(50) = 97 +/- 32 pM) and TM4 (ED(50) = 75 +/- 28 pM) cells, suggesting that all of these proteins are involved in the high affinity inhibin A binding complex. Immunoprecipitation of iodinated inhibin A complexed to TM3 and TM4 cells with an antibody against human betaglycan identified protein complexes of more than 200, 145, and 95 kDa. It is concluded that the high affinity binding complex for inhibin A found in these cell lines consists of betaglycan and several proteins of unknown identity and may represent the putative inhibin receptor complex.

Uterine expression of alternatively spliced mRNAs of mouse splicing factor SC35 during early pregnancy

RNA differential display was applied to identify genes critical for the establishment of pregnancy in the mouse. One of the gene fragments identified was homologous to human SC35 splicing factor; the mouse counterpart had not then been cloned. To obtain the full cDNA sequence of the mouse gene, a cDNA library was screened and four positive clones were fully analysed. Sequencing analysis indicated that we had cloned alternatively spliced mRNA species of mouse SC35 splicing factor. A map of splicing structure for this gene's pre-mRNA was then proposed and region-specific mRNA species were tested on Northern blots. This analysis indicated that the overall expression level of SC35 mRNA was much higher in implantation sites than in inter-implantation sites in the mouse uterus during early pregnancy. The expression of alternatively spliced mRNAs for SC35 was differently regulated both during early pregnancy and by steroid hormones. Embryo-derived factors were also implicated in the up-regulation of SC35 mRNA at implantation sites. These results demonstrate, for the first time, that an essential splicing factor is regulated in a complex manner during implantation in the mouse uterus. Hence, its correct regulation could be important for the success of pregnancy.

Inhibin and activin subunits are differentially expressed in endometrial cells and leukocytes during the menstrual cycle, in early pregnancy and in women using progestin-only contraception

Inhibins and activins are dimeric hormones which share common subunits and which have diverse endocrine and paracrine roles in regulating reproductive function. Endometrial expression of inhibin alpha, ssA and ssB subunits was examined by immunohistochemistry and in-situ hybridization, across the menstrual cycle and in early pregnancy. All three subunits were found to be expressed in endometrium, primarily by glandular epithelium in the early stages of the cycle. Following the onset of decidualization, expression of alpha, ssA and ssB subunits was up-regulated in decidualized stromal cells. A marked down-regulation of alpha subunit was detected in glandular epithelium, whilst expression of ssA and ssB subunits was maintained. This pattern was consistent in decidua from early pregnancy and additionally in endometrium from women using progestin-only contraceptives, either subdermal implants (Norplant((R))) or levonorgestrel-releasing intrauterine systems (Lng-IUS). Immunostaining was also observed for both ssA and ssB subunits in subpopulations of endometrial leukocytes, identified to be distinct subsets of macrophages, neutrophils and mast cells. Potential paracrine roles for activins may be envisaged in facilitating tissue remodelling during decidualization, in tissue repair following menstruation, and additionally in modulating premenstrual inflammatory events.

Temporal and hormonal regulation of inhibin protein and subunit mRNA expression by post-natal and immature rat ovaries

The contribution of specific follicle populations to dimeric inhibin production and inhibin subunit mRNA expression by the rat ovary has been investigated in two model systems, granulosa cells isolated from 25-day-old diethylstilboestrol (DES)-treated rats and post-natal rat ovaries, dispersed in culture or whole ovaries, using specific two-site immunoassays and 'real time' PCR. Media from FSH-stimulated granulosa cell cultures fractionated by gel filtration and RP-high performance liquid chromatography revealed two predominant peaks of alpha subunit activity which were attributed to alpha subunit and 31 k dimeric inhibin-A. The corresponding inhibin-B levels were low. FSH stimulation did not alter the ratio of inhibin-A:alpha subunit produced by granulosa cells. All three inhibin subunit mRNAs were expressed by granulosa cells, with eight-fold more alpha subunit mRNA relative to either of the beta subunits. Administration of DES to immature rats prior to the isolation of granulosa cells from the ovary led to beta(A) and beta(B) mRNA expression being down-regulated in the absence of any significant change in alpha subunit expression by the granulosa cells. Inhibin-A, -B and -alpha subunit were produced by basal and stimulated cultures of ovarian cells prepared from 4-, 8- and 12-day-old rats, indicating that primary, preantral and antral follicles contribute to total inhibin production. Consistent with these results, follicles within these ovaries expressed all three inhibin subunit mRNAs, with maximal expression observed in the ovaries of 8-day-old rats. The appearance of antral follicles in the ovary at day 12 led to a decline in the mRNA levels of each of the subunits but was most evident for the beta subunits. There was a profound influence of secondary preantral follicles on dimeric inhibin-A production, with FSH stimulation increasing inhibin-A relative to alpha subunit levels in cultures of ovarian cells prepared from 8-day-old rats. Thus, preantral follicles exposed to FSH contribute significantly to beta(A) subunit production by the ovary. In contrast, primary and preantral follicles did not produce inhibin-B in response to FSH stimulation. Transforming growth factor-beta (TGF-beta) enhanced, in a time-dependent manner, the production of the inhibin forms by ovarian cells in culture, although inhibin-B production was not responsive until day 8. The simultaneous treatment of ovarian cell cultures with FSH and TGF-beta elicited the greatest increases in production of all the inhibin forms. In summary, ovaries of 4-, 8- and 12-day-old rats expressed inhibin subunit mRNAs and produced dimeric inhibin-A and -B and free alpha subunit. Preantral follicles (day-8 ovarian cell cultures) were particularly sensitive to stimulation by FSH and TGF-beta and had a substantial capacity for inhibin production. The production of oestrogen by follicles may be instrumental in regulating inhibin production given that beta subunit mRNA expression was down-regulated by DES. The mechanisms by which inhibin-A and inhibin-B are individually regulated are likely to be similar during the post-natal period, when folliculogenesis is being established, and diverge thereafter, when inhibin-A becomes the predominant form in the fully differentiated ovary.

An age-related ovarian phenotype in mice with targeted disruption of the Cyp 19 (aromatase) gene

With the development of a mouse model of estrogen insufficiency due to targeted disruption of the aromatase gene [the aromatase knockout (ArKO) mouse], a new opportunity exists to examine the role of estrogen in ovarian follicular development. Ovaries and serum were collected from wild-type, heterozygous, and ArKO mice at 10-12 and 21-23 weeks and 1 yr of age. The ovaries were assessed histologically and stereologically, with primary, secondary, and antral follicles and corpora lutea counted. The uteri were hypoestrogenic, and serum levels of LH and FSH in ArKO females were elevated above those in heterozygote and wild-type animals at all ages studied. Although estrogen was not a prerequisite for reinitiation of follicle growth, there was a block of follicular development, and no corpora lutea were present in ArKO ovaries. Thus, the ArKO mouse was infertile as a consequence of disrupted folliculogenesis and a failure to ovulate. Hemorrhagic cystic follicles were present by 21-23 weeks of age. The ovarian phenotype degenerated with age, such that by 1 yr there were no secondary or antral follicles, and the primary follicles present were atretic. Extensive interstitial tissue remodeling occurred, exemplified by an influx of macrophages and collagen deposition, coincident with the loss of follicles. In conclusion, the ovarian environment in ArKO mice does not allow the characteristic development of follicles that culminates in ovulation and demonstrates an in vivo requirement of estrogen for normal ovarian function in the mouse.

The roles of activins, inhibins and estrogen in early committed follicles

The hypothesis that activin and inhibin are autocrine/paracrine mediators of ovarian folliculogenesis has a solid basis. In mouse and rat models, granulosa cells (GC) of committed follicles express mRNA and protein for the activin/inhibin subunits and mRNA for the activin receptors (type I and II). Dimeric inhibin-A and -B are produced by postnatal ovarian cell dispersates and (GC) in culture. Similar levels of inhibin-A and -B are produced by postnatal ovarian cells, but thereafter as the ovary develops, inhibin-A becomes the predominant form. Activin was more effective than transforming growth factor-beta (TGF-beta) in enhancing follicle stimulating hormone (FSH)-stimulated inhibin production by ovarian cells. Evidence for a local regulatory role of estrogen in the ovary is also accumulating. Murine models of estrogen receptor (ERalpha or ERbeta) disruption produce mice with abnormal ovarian phenotypes. Female mice, which lack the capacity to produce estrogen (ArKO mice), have arrested folliculogenesis, no corpora lutea, elevated levels of luteinising hormone (LH), FSH and testosterone and are infertile. These data are consistent with autocrine/paracrine actions of activin in the early growth of committed follicles and estrogen in follicular maturation.

Identification of monoclonal nonspecific suppressor factor beta (mNSFbeta) as one of the genes differentially expressed at implantation sites compared to interimplantation sites in the mouse uterus

Successful implantation requires synchronous development of and active dialogue between the maternal endometrium and the implanting blastocyst. While it is well established that appropriate maternal steroid hormones are essential for endometrial preparation for implantation, the molecular events at the actual site of implantation are still little understood. The aims of our studies were to identify genes explicitly expressed or repressed at the sites of implantation by utilising RNA differential display (DDPCR), and to establish the roles of these genes in the implantation process in a mouse model. Ten bands unique in implantation sites compared to interimplantation sites were identified by DDPCR and subsequently confirmed by Northern blotting. One of these bands contained a cDNA fragment that was highly homologous to mouse monoclonal nonspecific suppressor factor beta (MNSFbeta) or Fau. The full cDNA sequence of this gene, obtained by screening a lambdagt11 cDNA library, was essentially the same as MNSFbeta, except that it had much longer 5' untranslated region. Interestingly, both Northern and immunohistochemical analysis showed that the expression of this gene was much lower in implantation sites compared to interimplantation sites on day 4.5 of pregnancy, when embryos first attach to the uterus and initiate implantation, and on day 5.5, when implantation has advanced. These results suggest a role for MNSF during implantation and early pregnancy, possibly through regulating the proliferation and/or differentiation of uterine stromal cells. It may also be involved in the selective production of TH2-type cytokines in implantation sites to regulate the immune system at the maternal-fetal interface.

Complex regulation of calcium-binding protein D9k (calbindin-D(9k)) in the mouse uterus during early pregnancy and at the site of embryo implantation

Establishment of receptive endometrium is essential for implantation. Our aim was to identify and characterize genes uniquely regulated at the sites of implantation in mouse uterus by RNA differential display polymerase chain reaction (DDPCR). One of the gene fragments identified was 86% homologous to rat calcium-binding protein D9k (calbindin-D(9k)); the mouse counterpart had not then been cloned, but subsequently an mRNA sequence of mouse calbindin-D(9k) became available in GenBank (accession number: AF028071). This sequence is 99% homologous to the DDPCR-derived gene tag but has a shorter 3' end. Reverse transcription-polymerase chain reaction (RT-PCR) was performed using the sequence of 3' end of the DDPCR product and the 5' end of AF028071, and a full cDNA was obtained. This gene was primarily up-regulated by progesterone, but not by estrogen. It was further increased by the combination of the two steroids. Expression of calbindin-D(9k) was overall increased in the uterus during early pregnancy, but the level was significantly lower in implantation compared to interimplantation sites on Days 4.5 and 5.5 of pregnancy, becoming barely detectable in both sites after Day 6.5. In situ hybridization localized this mRNA predominantly in the luminal epithelium of the pregnant uterus. The complex regulation of calbindin-D(9k) in mouse uterus suggests an important role for this protein during pregnancy.

[Inhibin and ovarian cancer]

Previous observations from our laboratory have demonstrated that the levels of immunoreactive inhibin (ir-inh) are elevated in almost all patients with granulosa cell tumors and in the majority of postmenopausal women with mucinous ovarian cancers. The present report confirms these findings in a larger group of post-menopausal women. Immunohistochemistry for the inhibin alpha. beta A and beta B sununits shows predominantly epithelial staining in granulosa cell tumors and in the majority of mucinous cancers. Serous cystadenocarcinomas also frequently show positive staining. Studies seeking to identify G alpha i-2 or FSH receptor mutations have provided negative results in contrast to other reports. Further studies of the roles of the inhibin-related family of peptides in ovarian cancer diagnosis and monitoring are clearly indicated.