Different Stages Of Folliculogenesis Research Articles

P-522 Impact of TGFß/BMP/SMAD Pathway on Premature Ovarian Insuffiency (POI)

Abstract Study question Is TGFß/BMP/SMAD pathway altered in women with POI and can results be detected from peripheral blood samples? Summary answer The TGFß/BMP/SMAD pathway mRNA-expression-alterations are detectable in leukocytes of women with Premature Ovarian Insufficiency (POI) paving the way to use it as predictive tool. What is known already A proper ovarian function relies on a complex system of signalling molecules including several BMP/TGFß-superfamily-members expressed in the ovary at different stages of folliculogenesis acting via two types of Serine/Threonine Kinase receptors. The downstream located SMAD proteins are classified into three subclasses according to their function as activated R-SMADs1,2,3,4,9, common-partner SMAD4 or inhibitory SMADs6,7. Mutations in BMPR2 and its ligands have been shown to be related to POI. Recently neurologic studies demonstrated that FMRP(Fragile-X-Mental-Retardation-1-Protein) represses BMPR2 and its gene FMR1(Fragile X Mental-Retardation-1) is one major regulator of follicular development and the most frequent genetic cause of POI if premutated. Study design, size, duration RT-q-PCR was performed to measure the mRNA-levels of SMAD 1,3,4,5, BMPR2 and FMR1. cDNA was synthesized using RNA obtained from leucocytes of patients with POI and of the control group with a normal ovarian reserve. 163 patients diagnosed with POI and 51 women in the control group were recruited between 2008 and 2022 at Heidelberg University’s Women’s Hospital. Participants/materials, setting, methods Blood samples were drawn from every participant to extract leucocyte-RNA and synthesize non-specific cDNA. RT-q-PCR was performed with TaqMan reagents to quantify relative mRNA-expression levels of SMAD 1,3,4, 5, BMPR2 and FMR1. Statistical analysis was performed with Microsoft Excel and GraphPad Prism 10 using the 2–ΔΔCt method and Mann-Whitney-Test. Statistical significance was set to p = 0.05. Main results and the role of chance In our investigation, we observed a consistent and statistically significant decrease in the expression levels of all tested SMADs—SMAD1, SMAD3, SMAD4, and SMAD5—in leukocytes of women diagnosed with POI compared to unaffected controls. The p-values amounted to p < 0.0001 for SMAD1, p = 0.0340 for SMAD3, p < 0.0001 for SMAD4, and p = 0.0076 for SMAD5. However, we did not identify notable differences in the expression levels of FMR1 and BMPR2 between the two groups. These results suggest an alteration in the regulation of the activated downstream elements SMAD 1, 3, and 5 and their common partner SMAD4 in women with POI, emphasizing its potential role as a contributing factor to diminished ovarian function. These effects seem to be independent of BMPR2 and FMR1 and regulated by other receptors and or ligands. Limitations, reasons for caution Our data are limited to mRNA-levels. So further experiments including protein-level and their phosphorylation-status are needed to receive an overall assessment of its impact on ovarian damage. It’s worth noting that the study is concentrated on leukocytes as potential diagnostic tool and results should be cross-checked in ovarian-tissue and cells. Wider implications of the findings The identified alteration in TGFß/BMP/SMAD pathway gene expression in women with POI suggest a role in ovarian damage. Lower expression levels in the aforementioned mRNAs could serve as a potential predictive biomarker for POI risks and putatively used in consultations of women prior to fertility treatment and/or preservation. Trial registration number not applicable

Anti-Müllerian hormone induces autophagy to preserve the primordial follicle pool in mice.

The reserve pool of primordial follicles (PMFs) is finely regulated by molecules implicated in follicular growth or PMF survival. Anti-Müllerian hormone (AMH), produced by granulosa cells of growing follicles, is known for its inhibitory role in the initiation of PMF growth. We observed in a recent invivo study that injection of AMH into mice seemed to induce an activation of autophagy. Furthermore, injection of AMH into mice activates the transcription factor FOXO3A which is also known for its implication in autophagy regulation. Many studies highlighted the key role of autophagy in the ovary at different stages of folliculogenesis, particularly in PMF survival. Through an invitro approach with organotypic cultures of prepubertal mouse ovaries, treated or not with AMH, we aimed to understand the link among AMH, autophagy, and FOXO3A transcription factor. Autophagy and FOXO3A phosphorylation were analyzed by western blot. The expression of genes involved in autophagy was quantified by RT-qPCR. In our invitro model, we confirmed the decrease in FOXO3A phosphorylation and the induction of autophagy in ovaries incubated with AMH. AMH also induces the expression of genes involved in autophagy. Interestingly, most of these genes are known to be FOXO3A target genes. In conclusion, we have identified a new role for AMH, namely the induction of autophagy, probably through FOXO3A activation. Thus, AMH protects the ovarian reserve not only by inhibiting the growth of PMFs but also by enabling their survival through activation of autophagy.

Role of glucose metabolism and signaling pathways at different stages of ovarian folliculogenesis

The female ovaries are critical for follicle growth and development in the process known as “folliculogenesis”. This complex process is regulated by various factors, among which the microenvironment around follicles appears to be crucial. According to previous studies, folliculogenesis is an energy-demanding process. In fact, well-balanced follicular energy metabolism is associated with ovarian function and female fertility. Consequently, glucose metabolism has been widely described as the main source of energy during folliculogenesis. Generally, the follicular glucose metabolism profiles change dynamically during follicular development. Metabolic abnormalities during folliculogenesis are associated with aging, primary ovarian insufficiency, and polycystic ovary syndrome, thereby leading to subfertility and infertility in females. The signaling pathways in follicles appear to form a link between glucose metabolism and folliculogenesis. Therefore, a better understanding of glucose metabolism dynamics at different stages of folliculogenesis and the associated signaling pathways will provide potential implications for follicle developmental competence. This review aimed to describe variations in glucose metabolism at different stages of folliculogenesis, provide new insights into glucose metabolic disorder-related diseases, and specifically discuss two major signaling pathways that regulate glucose metabolism during folliculogenesis: phosphatidylinositol 3-kinase, protein kinase B (PI3K-PKB/AKT), and AMP-activated protein kinase (AMPK) signaling pathways.

First detailed description of follicle development in a chimaeroid, the American elephant fish Callorhinchus callorhynchus

Chimaerods represent an enigmatic lineage of cartilaginous fishes and the least studied group within Chondrichthyans. They have a widespread global distribution with a high degree of endemism. In addition, this group has been considered among the least threatened species of Chondrichthyans, but also the most data-deficient group, with biological information lacking for most species. This study represents the first microanatomical, histological, and ultrastructural description of the different stages of folliculogenesis in Callorhinchus callorhynchus, and the first ultrastructural study about this topic within chimaeroids. Specimens of different maturity stages were collected from landings of the commercial fleet operating in San Matías Gulf, Argentina. Folliculogenesis shows some differences compared to other elasmobranchs. Oogonia were present in immature and mature females. Atretic follicles of different sizes were present in mature female ovaries. There is a significant difference between the macroscopic (∼10 mm) and microscopic (∼ 2 mm) follicular size at the beginning of vitellogenesis. There is no evidence of an epigonal organ. The results are discussed in a physiological and reproductive context. This study provides valuable information that will contribute to the understanding of the reproductive biology of the chimaeroids species and its potential for fishery exploitation recovery.

Identification of Biomarkers for Predicting Ovarian Reserve of Primordial Follicle via Transcriptomic Analysis.

Ovarian reserve (OR) is mainly determined by the number of primordial follicles in the ovary and continuously depleted until ovarian senescence. With the development of assisted reproductive technology such as ovarian tissue cryopreservation and autotransplantation, growing demand has arisen for objective assessment of OR at the histological level. However, no specific biomarkers of OR can be used effectively in clinic nowadays. Herein, bulk RNA-seq datasets of the murine ovary with the biological ovarian age (BOA) dynamic changes and single-cell RNA-seq datasets of follicles at different stages of folliculogenesis were obtained from the GEO database to identify gene signature correlated to the primordial follicle pool. The correlations between gene signature expression and OR were also validated in several comparative OR models. The results showed that genes including Lhx8, Nobox, Sohlh1, Tbpl2, Stk31, and Padi6 were highly correlated to the OR of the primordial follicle pool, suggesting that these genes might be used as biomarkers for predicting OR at the histological level.

Expression and characterisation of Fmr1 splice variants during folliculogenesis in the rat.

The FMR1 gene consists of 17 exons and codes for the FMRP protein. FMR1 is involved in four genetic disorders depending on the CGG repeats length in its 5'UTR: the full mutation is responsible for the Fragile X syndrome while the premutation is associated with the Fragile X-associated Tremor/Ataxia Syndrome, Fragile X-associated Primary Ovarian Insufficiency (FXPOI) and Fragile X-associated neuropsychiatric disorders. FMR1 presents multiple isoforms resulting from skipping of exons 12 and 14 and the use of alternative splice sites in exons 15 and 17. To investigate the expression of Fmr1 splicing variants during folliculogenesis in the rat. We used preantral, early antral and preovulatory follicles to isolate RNA and characterise, by fluorescent PCR followed by sequencing, all the isoforms present in the different follicular stages. We identified two isoforms resulting from splicing of exon 12, six isoforms resulting from splicing of exon 14 and 15 and one isoform for exon 17. The expression levels of the isoforms vary within each follicular stage but not between different stages of folliculogenesis. Importantly, we identify for the first time in rat, an isoform that contains exon 12 and two isoforms, one that includes and one that excludes exon 14 and use the third acceptor site in exon 15. Characterisation of the different FMR1 variants expressed during folliculogenesis will help to understand the potential distinct cellular roles of each of them and the possible implication in the development of FXPOI.

Newly Identified Regulators of Ovarian Folliculogenesis and Ovulation.

Each follicle represents the basic functional unit of the ovary. From its very initial stage of development, the follicle consists of an oocyte surrounded by somatic cells. The oocyte grows and matures to become fertilizable and the somatic cells proliferate and differentiate into the major suppliers of steroid sex hormones as well as generators of other local regulators. The process by which a follicle forms, proceeds through several growing stages, develops to eventually release the mature oocyte, and turns into a corpus luteum (CL) is known as “folliculogenesis”. The task of this review is to define the different stages of folliculogenesis culminating at ovulation and CL formation, and to summarize the most recent information regarding the newly identified factors that regulate the specific stages of this highly intricated process. This information comprises of either novel regulators involved in ovarian biology, such as Ube2i, Phoenixin/GPR73, C1QTNF, and α-SNAP, or recently identified members of signaling pathways previously reported in this context, namely PKB/Akt, HIPPO, and Notch.

Expression of FOXL2 and RSPO1 in Hen Ovarian Follicles and Implication of Exogenous Leptin in Modulating Their mRNA Expression in In Vitro Cultured Granulosa Cells.

Simple SummaryIn highly efficient laying hens, such as in commercial layer lines, the development of follicles is mainly characterized by an organized follicular hierarchy. Leptin has been implicated in the modulation of female reproduction in vertebrate animals. Forkhead box L2 (FOXL2) and R-spondin1 (RSPO1) have also been implicated in the regulation of ovarian functions and the development of follicles. In this study, using a laying hen model, we observed abundant mRNA expression of FOXL2 and RSPO1 in small (prehierarchical) and large (hierarchical) follicles, respectively. FOXL2 mRNA expression was stable in granulosa cells harvested from 3–5 mm to F4 follicles, and exhibited a significantly higher expression in large hierarchical follicles. However, theca cells exhibited a significantly higher mRNA expression of RSPO1 in F4 to F1 follicles. In subsequent experiment, we observed that 100 ng/mL leptin significantly modulated FOXL2 and RSPO1 expression in cultured granulosa cells harvested from large hierarchical and small prehierarchical follicles. These findings reasonably suggest that FOXL2 and RSPO1 genes may have a role in modulating the ovarian mechanisms, possibly affecting follicle growth and selection in laying hens. In addition, we demonstrated that leptin administration to granulosa cells in vitro modulated FOXL2 and RSPO1 expression, suggesting an implication of leptin in the follicular development and steroidogenesis in laying hens. However, further focused studies are warranted to improve our understanding of the exact roles played by these genes in follicle development and selection in laying hens.In this study, using a laying hen model, we determined the expression of FOXL2 and RSPO1 in different central and peripheral tissue and ovarian follicles at different stages of development. At the same time, mRNA expression of both genes in granulosa and theca cells harvested from follicles at different stages of folliculogenesis was also evaluated. Finally, we assessed the effect of leptin treatment on expression of FOXL2 and RSPO1 in in vitro cultured granulosa cells harvested from 1–5 mm to F3–F1 follicles. Our RT-qPCR results revealed that a comparatively higher expression of FOXL2 and RSPO1 was observed in ovary, hypothalamus, and pituitary. Abundant mRNA expression of FOXL2 was observed in small prehierarchical follicles (1–1.9 and 2–2.9 mm follicles; p < 0.05), whereas mRNA expression of RSPO1 showed an increasing trend in large hierarchical follicles (F5–F1), and its abundant expression was observed in post-ovulatory follicles. FOXL2 mRNA expression was stable in granulosa cells harvested from 3–5 mm to F4 follicles, and exhibited a significantly higher expression in large hierarchical follicles. Conversely, relatively low mRNA expression of FOXL2 was observed in theca cells. RSPO1 mRNA expression was relatively lower in granulosa cells; however, theca cells exhibited a significantly higher mRNA expression of RSPO1 in F4 to F1 follicles. In the next experiment, we treated the in vitro cultured granulosa cells with different concentrations (1, 10, 100, and 1000 ng/mL) of exogenous leptin. Compared to the control group, a significant increase in the expression of FOXL2 was observed in groups treated with 1, 10, and 100 ng/mL leptin, whereas expression of RSPO1 was increased in all leptin-treated groups. When treated with 100 ng/mL leptin, FOXL2 and RSPO1 expression was upregulated in cultured granulosa cells harvested from both large hierarchical (F3–F1) and small prehierarchical follicles (1–5 mm). Based on these findings and evidence from mainstream literature, we envisage that FOXL2 and RSPO1 genes (in connection with hypothalamic-hypophysis axis) and leptin (via modulation of FOXL2 and RSPO1 expression) might have significant physiological roles, at least in part, in modulating the ovarian mechanisms, such as follicle development, selection, and steroidogenesis in laying hens.

Effects of varying dietary levels of &lt;i&gt;Carica papaya&lt;/i&gt; seed meal powder (PSM) on growth and histology of gonads in &lt;i&gt;Oreochromis niloticus&lt;/i&gt; larvae

Sex control in tilapia should provide an invaluable benefit to aquaculture. The effects of different dietary levels of papaya carica seed meal powder on growth and gonad histology in Oreochromis niloticus larvae were studied to prevent early maturity and uncontrolled spawning. Four (4) dietary level of seed meal powder, varying from 0 g.Kg –1 as a control; 1 g.Kg –1 ; 2 g.Kg –1 to 3 g.Kg –1 were each tested in triplicate. The diet were isonitrogenous and were fed to twelve (12) experimental groups of 110 larvae weighing 0.019 g at a feeding rate of 4% body weight, three times a day for 30 days with the experimental diet and then after fed with the basal diet for other 60 days of the experiment. At the end of the experiment, 24 fish from all replicates were randomly sampled, slaughtered and dissected to remove testicles and ovaries. Testicular and ovarian sampleswere fixed in 10% buffered formalin for 24 h before the histological process. After 90 days of experiment, fish weight increased from 0.019 g ± 0.09 to 32.47g ± 0.02; 30.40g ± 0.05; 34.68 g ± 0.07 and 33.83 g ± 0.09 respectively for C. papaya dosage of 0; 1; 2 and 3, respectively. In fish treated with 0 and 1 g.Kg -1 of PSM, the testes showed different stages of spermatogenesis with germ cells moving up to the spermatozoa. Similarly, the ovaries showed follicles at different stages of folliculogenesis up to vitellogenesis. The main lesional changes observed concerned the testicles of fish fed with 2 and 3 g.Kg -1 PSM with in particular the scarcity of germ cells and spermatozoa. For females, the only observations concern vitellogenesis which are important for treatment doses of 0 and 1 g.Kg -1 , while they decrease in the group treated with 3 g.Kg -1 . © 2019 International Formulae Group. All rights reserved Keywords: Papaya seed meal powder, Performances, Gonads histology, Oreochromis niloticus

Histological and immunohistochemical evaluation of granulosa cells during different stages of folliculogenesis in bovine ovaries.

Bovine granulosa cells (GC) vary in their morphological aspect during different stages of folliculogenesis. In this study, 10 morphologically normal bovine ovaries were collected to study the structural aspects of different stages of GC using intermediate filament protein antibodies including cytokeratin AE1/AE3 (AE1/AE3), vimentin, nectin-4 and desmin. Hormonal immunolocalization was assessed using the immunomarkers anti-Müllerian hormone (AMH) and inhibin alpha. In addition, tumour markers and proliferation markers using c-erbB-2 oncoprotein and proliferating cell nuclear antigen, respectively, were investigated. The immunolabelling of AE1/AE3 in GC was strongest in the early follicle stage and gradually decreased when reaching the Graafian follicle stage. Its immunolabelling increased again as the stage progressed from stage I to stage III. The immunolabelling of inhibin alpha was inversely proportional to that of AE1/AE3 in the developing ovarian follicles as their immunolabelling is opposite to each other during folliculogenesis. AMH was immunopositive in almost all GC stages in different intensities and percentages, except for some negative staining in the atretic IV follicles. The atretic IV follicle is a unique type of atretic follicle that shows Call-Exner body formation, which was mainly found in older cows in this study. The distinct patterns of immunoreactivity for various types of immunomarkers in the different GC stages will play an important role in diagnostic assistance of various follicle conditions, including cystic ovaries and GC tumours.

Expression dynamics of the serotonergic system components in granulosa cells of the developing ovarian follicle and after luteinization

Regulation of the growth and development of female sex cells is one of the conservative functions of serotonin, but their specific mechanisms remain undisclosed yet. Molecular-genetic study of the presence of all components of the serotonergic system and dynamics of their expression in granulosa cells at different stages of folliculogenesis and in corpus luteum was carried out by reverse transcription with PCR and real-time PCR. Transcripts of enzymes tryptophan hydroxylase Tph1, aromatic amino acids decarboxylase Ddc and monoamine oxidase Maoa, membrane serotonin transporter Sert and vesicular monoamine transporter Vmat2, as well as serotonin receptors Htrlb, Htrld, Htr2a, Htr2b, Htr5b and Htr7 are detected in probes investigated. A quantitative study revealed that the expression of Vmat2, Htrlb, and Htr7 genes is greater in the early stages of folliculogenesis, whereas the expression of the Vmatl gene grows by the late stages of follicular development. The relative quantity of the mRNA of the Ddc, Maoa, Vmatl and Htrlb genes increases during luteinization, while the expression of the Vmat2 and Htr7 genes, on the contrary, decreases. The presence of expression of key components of the serotonergic system and its dynamics allow as to suggest that they are involved in serotonergic regulation of folliculogenesis, as well as luteinization.

Effects of vitrification and transplantation on follicular development and expression of EphrinB1 and PDGFA in mouse ovaries

The aim of this study was to assess the follicular development and the patterns of EphrinB1 and PDGFA immunostaining in vitrified mouse ovarian tissue (OT) with and without transplantation. Histological evaluation was performed on fresh and vitrified OTs, whether transplanted or not. RT-PCR was performed on fresh and vitrified ovarian samples (OSs) and vitrified OS graft. Vitrification alone did not significantly reduce the normal primordial, primary, and secondary follicles except antral ones (p > 0.05). However, transplantation decreased all the follicle types. The EphrinB1 immunoexpression showed high intensity in all follicular types in vitrified OT and the significant increased was detected in secondary and antral follicles (p < 0.05). PDGFA protein immunoexpression of primordial and primary follicles was decreased in vitrified OT (p < 0.05). However, the lowest immunoexpression of EphrinB1 and PDGFA was detected after transplantation (p < 0.05). The levels of ephrinb1 and pdgfa mRNA expressions in vitrified OS and vitrified OS grafts were found as comparable to the fresh OS. In conclusion, vitrification has no detrimental effect on the follicles at the different developmental stages, majority of ovarian follicular loss takes place after transplantation rather than vitrification. Overall, vitrification and grafting do not change the ephrinb1 and pdgfa gene expressions. In addition, EphrinB1 and PDGFA are expressed during different stages of folliculogenesis in a different manner in fresh, vitrified, or grafted OTs. Vitrification and/or grafting appear to affect the follicular expression of EphrinB1 and PDGFA. These findings suggest that these proteins could have several functions related to the development of follicles and angiogenesis after transplantation.

Mouse Double Minute 2 Actively Suppresses p53 Activity in Oocytes during Mouse Folliculogenesis

The p53 signaling network is indispensible in cellular stress responses and tumor suppression. Negative regulations of p53 by mouse double minute 2 (MDM2) and its homolog MDM4 are an integrated component of the network and have been implicated in regulating the stress responses and the maintenance of normal development and homeostasis of multiple somatic cell lineages. However, the regulatory role of MDM2 on p53 and stress responses in female germ cells remains undetermined. Here, we used the Cre-loxP system to delete Mdm2 in oocytes at different stages of folliculogenesis in mice. Mdm2 deletion resulted in a clear p53 nuclear accumulation in the oocytes and impeded fertilities with early follicular loss in mice, resembling human premature ovarian failure phenotypes. These phenotypes were fully rescued by concurrent deletion of p53 in mice. In addition, Nutlin-3, a small molecule compound that inhibited the binding of MDM2 to p53, also promoted p53-dependent oocyte death. Although cancer therapeutic agents 5-fluorouracil and doxorubicin could not induce a robust p53 activation in the wild-type oocytes, they induced p53 nuclear accumulation in the Mdm2 and Mdm4 double heterozygous oocytes. These results demonstrated a critical prosurvival role for MDM2 in the oocytes. Moreover, they suggested a more tightened and rigorous regulatory mode for the MDM2/MDM4-p53 network in female germ cells under stress situations.

Meta-analysis of gene expression profiles in granulosa cells during folliculogenesis

Folliculogenesis involves coordinated profound changes in different follicular compartments and significant modifications of their gene expression patterns, particularly in granulosa cells. Huge datasets have accumulated from the analyses of granulosa cell transcriptomic signatures in predefined physiological contexts using different technological platforms. However, no comprehensive overview of folliculogenesis is available. This would require integration of datasets from numerous individual studies. A prerequisite for such integration would be the use of comparable platforms and experimental conditions. The EmbryoGENE program was created to study bovine granulosa cell transcriptomics under different physiological conditions using the same platform. Based on the data thus generated so far, we present here an interactive web interface called GranulosaIMAGE (Integrative Meta-Analysis of Gene Expression), which provides dynamic expression profiles of any gene of interest and all isoforms thereof in granulosa cells at different stages of folliculogenesis. GranulosaIMAGE features two kinds of expression profiles: gene expression kinetics during bovine folliculogenesis from small (6 mm) to pre-ovulatory follicles under different hormonal and physiological conditions and expression profiles of granulosa cells of dominant follicles from post-partum cows in different metabolic states. This article provides selected examples of expression patterns along with suggestions for users to access and generate their own patterns using GranulosaIMAGE. The possibility of analysing gene expression dynamics during the late stages of folliculogenesis in a mono-ovulatory species such as bovine should provide a new and enriched perspective on ovarian physiology.

Expression and localization of Smad2 and Smad4 proteins in the porcine ovary

The objective of the present study was to investigate the temporal and spatial expression of Smad2 and Smad4 proteins, the downstream signaling molecules of the transforming growth factor beta (TGF-β) superfamily, in the porcine ovary. Cellular localization of Smad2 and Smad4 proteins was examined using immunohistochemistry. The specificity of the antibodies was examined using Western blot assay. Western blot analyses demonstrated that 52kDa Smad2 and 60kDa Smad4 proteins were expressed in the porcine ovary. Immunohistochemistry revealed that Smad2 and Smad4 were widely expressed in the porcine ovary, mainly localized in the oocyte, granulosa and thecal cells at different stages of folliculogenesis. Within the primordial and primary follicles, Smad2 and Smad4 showed strong staining in oocytes and follicular cells. In the antral follicle, strong staining was observed in oocytes, granulosa and theca cells. These findings suggest that Smad2 and Smad4 may be a key regulator of follicular development and growth of oocytes in the porcine ovary.

The regulation and assessment of follicular growth

Folliculogenesis is the process by which waves of small primordial follicles possessing immature oocytes are recruited to undergo development into large antral follicles, with one then being selected for ovulation of a fully competent oocyte. Folliculogenesis can be divided into three stages: follicle recruitment, selection and ovulation, and has two phases: the initial gonadotrophin-independent phase and the later gonadotrophin-dependent phase. It involves an elaborate array of biochemical signalling factors, both stimulatory and inhibitory, and the regulation of follicle growth relies on these being tightly controlled. Their increasing understanding allows reproductive biologists to attempt manipulation of folliculogenesis, which can be useful in clinical areas such as assisted reproduction and contraception. The rising average age of childbearing in many developed countries is bringing an additional focus on the importance of assessing a woman's non-growing follicular pool; i.e. her ovarian reserve. This review examines the important regulatory players in the different stages of folliculogenesis and describes some of the currently available measures of ovarian reserve.

Establishment and validation of a model for non-luteinized human mural granulosa cell culture

Cell culture techniques of human mural granulosa cells (MGCs) serve as a major in vitro tool. However, the use of luteinized MGCs has major limitations due to their luteinized state. Our aim was to establish a standardized protocol for the culture of MGCs as a model for different stages of folliculogenesis. We showed that early-non-luteinized, preovulatory-non-luteinized and luteal-MGCs have distinct gene expression pattern. After 4days of incubation of luteinized-MGCs, ovulatory genes mRNA’s achieve expression levels similar to the early non-luteinized follicles. FSH stimulation for 48h of these 4days cultured MGCs showed ovulatory genes mRNA’s expression similar to the pre-ovulatory non-luteinized follicles. These FSH-stimulated cells responded to hCG stimulation in a pattern similar to the response of pre-ovulatory follicles.This novel model may provide a standardized research tool for delineation of the molecular processes occurring during the latter stages of follicular development in the human ovary.

Forkhead transcription factors in ovarian function

Since the discovery of the conserved forkhead (Fkh) DNA binding domain more than 20 years ago, members of the Fkh or forkhead box (FOX) family of transcription factors have been shown to act as important regulators of numerous developmental and homeostatic processes. The human genome contains 44 Fkh genes, several of which have recently been reported to be essential for female fertility. In this review, we highlight the roles of specific FOX proteins in ovarian folliculogenesis and present our current understanding of their molecular function. In particular, we describe what we have learned from loss-of-function studies using mouse models as well as human genetics and illustrate how different stages of folliculogenesis, both in oocytes and in somatic granulosa and theca cells, are regulated by FOXC1, FOXL2, and FOXO subfamily members.

Stage-specific mice ovarian somatic cell is involved in primordial folliculogenesis

Although recent studies have shown that female germ cells can be produced from stem-cell lines in mice, whether these germ cells can interact with ovarian somatic cells (OSCs) to form primordial follicles (PFs) is still unclear. Here, we found after the PF pool is established, Irx3 and FoxL2 which were extensively expressed in the OSCs of the perinatal mouse decreased. Additionally, during primordial folliculogenesis, down-regulation of FoxL2 prevents OSCs invading germ cell cysts. Therefore, we investigated whether OSCs at different stages of folliculogenesis were able to reconstitute PFs with fetal ovarian germ cells in vitro. In this system, neither OSCs at the post-PF pool-establishment stage nor OSCs from normal or doxorubicin-treated adult mice were able to reconstitute PFs. Mice eliminated most of pre-existing PFs failed to exhibit any spontaneous regeneration of PFs. Our results suggest that OSCs can only support physiological primordial folliculogenesis during the prenatal period. OSCs lose the ability to form PFs after the establishment of the PF pool may be another reason why the PF pool is non-renewable in most adult mammals.

415. Increased expression of an androgen receptor regulated gene, kit ligand, in polycystic ovaries

Polycystic ovaries (PCO) are induced by pathological or pharmacological female androgen excess, but the role of the androgen receptor (AR) in the pathogenesis of PCO is unknown. We therefore tested the hypothesis that PCO have increased expression of AR or kit ligand (KITL), a cytokine that was recently identified as a candidate AR-regulated gene in the ovary (1). Immunohistochemical analysis of AR and KITL expression was performed on archival paraffin-embedded sections of 8 morphologically normal and 8 polycystic ovaries from women under the age of 40 years. Stained sections were scanned with a NanoZoomer Digital Pathology System and immunoreactivity was qualitatively assessed using a 0-3+ scale, where 3+ represents the most intense staining. Electronic images of follicles at different stages of folliculogenesis were assessed by two independent observers who were blinded to the morphology of the source ovary. Each individual ovary contributed a minimum of 1 follicle per size class and a minimum of 10 follicles per size class were analysed. AR immunoreactivity was present in granulosa cells at all stages of folliculogenesis, in thecal cells of large antral follicles, and in the ovarian stroma. Staining intensity for AR did not differ between normal and polycystic ovaries. KITL expression, summarised in Table 1, was found to be significantly elevated in the oocytes of primordial and primary follicles and in the granulosa cells of follicles at all stages of folliculogenesis. These results show that AR expression is normal in PCO but expression of an AR-regulated gene is increased, potentially due to an excess of androgen hormone that is characteristic of women with PCO. Based on the roles of KITL established by murine studies, increased expression of KITL could explain many of the features of PCO including follicle excess, hyperthecosis and abnormal androgen secretion.