Transcriptional profiling of five isolated size-matched stages of human preantral follicles

Human platelet lysate improves the growth and survival of cultured human pre-antral follicles

RESEARCH QUESTION

How do platelet-rich plasma products like human platelet lysate (HPL) and umbilical cord plasma (UCP) affect the growth and survival of isolated human pre-antral follicles in vitro?

DESIGN

Human pre-antral follicles (n = 724; mean diameter: 75 µm; range: 46-237 µm) were isolated from ovarian medulla donated by 14 patients undergoing unilateral oophorectomy for ovarian tissue cryopreservation. Follicles were encapsulated in 0.5% alginate and cultured for 8 days in media supplemented with 5% fetal bovine serum (FBS) (n = 171), 2.5% human serum albumin (HSA) (n = 159), 5% HPL (n = 223) or 5% UCP (n = 171).

RESULTS

The survival probability was significantly higher in the group supplemented with HPL (80%) compared with the other three groups: FBS (54%, P < 0.001); HSA (63%, P = 0.004) and UCP (29%, P < 0.001). Surviving follicles in the UCP group had less defined follicular membranes and decompacted granulosa cell layers. The median growth of surviving follicles was significantly (P < 0.001) larger in the HPL group (73 µm) compared with any of the other three groups: HSA (43 μm); FBS (40 μm) UCP (54 μm). A descriptive analysis of follicular secretion of anti-Müllerian hormone and oestradiol did not reveal any difference between the groups. The detectability of follicular genes was high for AR (100%), AMHR2 (100%) and FSHR (76%), whereas few follicles expressed LHR (20%).

CONCLUSION

Human platelet lysate significantly improved survival and growth of cultured human pre-antral follicles compared with FBS, HSA and UCP. The use of HPL is a valuable improvement to culture human pre-antral follicles but further studies will have to prove whether the superiority of HPL translates into better quality oocytes.

Expression of genes and enzymes involved in ovarian steroidogenesis in relation to human follicular development

Introduction

Granulosa cells (GCs) and theca cells (TCs) play a pivotal role in human ovarian steroidogenesis, facilitating the conversion of cholesterol into sex steroids that regulate normal reproductive function. This study aims to explore the expression patterns of key enzymes that govern human ovarian steroidogenesis throughout follicle development, employing both genomic and immunological methodologies.

Methods

Follicles and GCs obtained from women undergoing ovarian tissue cryopreservation (OTC) and in vitro fertilisation treatment were utilized. Gene expression data were obtained from a Chinese study using RNA sequencing and from microarray data generated in our laboratory to comprehensively analyse gene expression profiles across distinct stages of follicular development. To corroborate the localisation of key enzymes within GCs and TCs, immunohistochemistry analyses utilizing colourimetric and fluorescent techniques were conducted.

Results

Steroidogenesis-related enzymes displayed low gene expression levels during early follicle development. However, a notable upregulation of HSD3B2 was observed in GCs as follicles progressed to the antral/preovulatory stage, confirmed consistently using both microarray and RNA sequencing methodologies. Furthermore, immunohistochemical analyses effectively demonstrated that HSD3B2 were not only expressed in GCs, but co-localised with CYP17A1 within a specific subset of TCs surrounding human small antral follicles. Contributing to an enhanced progesterone production during the second half of the follicular phase was a significant upregulation of CYB5A in both microarray and RNA-seq datasets as follicles transition from the antral stage to the pre-ovulatory stage. Moreover, an augmented expression of DHCR24 and LDLR in both types of data, along with HMGCR expression expression in the microarray data, indicates increased substrate availability for ovarian steroidogenesis.

Discussion

This study confirms and extends that GCs gradually augment expression of HSD3B2 thereby enhancing their capacity for progesterone synthesis as follicles reach the size of selection at around 10 mm in diameter. This is supported by the expression CYB5A and possibly augmented availability of steroid precursors. A subset of TCs exhibit concurrent expression of CYP17A1 and HSD3B2, collectively contributing to the synthesis of 17-hydroxyprogesterone. These data significantly enhance our understanding of the dynamic regulation of progesterone throughout the process of follicular development.

Follicle outcomes in human ovarian tissue: effect of freezing, culture, and grafting

OBJECTIVE

To study the effect of freezing, in vitro culture (IVC) and grafting to chorioallantoic membrane (CAM) on follicle outcomes in human ovarian tissue.

DESIGN

An experimental study.

SETTING

University-based research laboratory.

PATIENTS

Fresh and cryopreserved ovarian tissue from 10 patients was donated to research with their consent and institutional review board approval.

INTERVENTIONS

Fresh and frozen-thawed ovarian cortical pieces were in vitro-cultured and compared (fresh-IVC vs FT-IVC). The FT-IVC fragments were then examined against fragments grafted to CAM (FT-CAM). After both IVC and CAM grafting, ovarian cortical pieces (4×2×1 mm³) were analyzed on days 0, 1, and 6.

MAIN OUTCOME MEASURES

Follicle analyses included histology (count and classification) and immunohistochemistry (Ki67 [proliferation], caspase-3 [apoptosis], 1A and 1B light chain 3B [autophagy], p-Akt, FOXO1, and p-rpS6 [PI3K activation]). Droplet digital polymerase chain reaction further explored expression of PI3K pathway- and oocyte-related genes in tissue sections.

RESULTS

No major differences were detected between fresh-IVC and FT-IVC tissues in any conducted analyses. Although a significant drop was observed in primordial follicle (PF) proportions in the fresh-IVC and FT-IVC groups (d0 vs. d6, P<.002), they held steady in the FT-CAM group (d0 vs. d6, P>.05). The PF rates were also significantly higher in the FT-CAM group than the FT-IVC group on d6 (P=.02). Importantly, avian erythrocytes were already present in 30% of implants from d1. Apoptotic and autophagic follicle rates increased during IVC (P<.008), but remained significantly lower in the FT-CAM group (P<.01), confirming superior follicle preservation in CAM-grafted tissue. Upregulation of the PI3K/FOXO pathway was established in the IVC groups, demonstrating PF activation, whereas significant pathway downregulation was detected in the FT-CAM group (P<.03). The droplet digital polymerase chain reaction tests confirmed oocyte growth during IVC and follicle autophagy in all groups; however, the PI3K pathway appeared to be differentially modulated in tissues and follicles.

CONCLUSIONS

In vitro culture induces PF depletion with no additional impact of freezing. Grafting to CAM preserves the PF pool by curbing follicle activation, apoptosis, and autophagy, probably thanks to rapid graft revascularization and/or the circulating embryonic antimüllerian hormone. These findings highlight the importance of enhancing neoangiogenesis in ovarian grafts and investigating the potential benefits of administering antimüllerian hormone to prevent PF burnout.

Investigation of the role of X chromosome inactivation and androgen receptor CAG repeat polymorphisms in patients with recurrent pregnancy loss: a prospective case-control study

BACKGROUND

Previous research has revealed that skewed X chromosome inactivation (SXCI) and androgen receptor (AR) CAG polymorphisms are associated with increased risk of recurrent pregnancy loss (RPL); however, the results are conflicting, and the underlying mechanisms remain unclear. This study investigated the role of SXCI and AR CAG polymorphisms in patients with RPL and explored whether the underlying mechanisms were related to the ovarian reserve and preimplantation embryo aneuploidy.

METHODS

This was a prospective case-control study carried out in a tertiary hospital-based reproductive medicine center. An external validation RPL cohort was recruited during the study period. Data on baseline and cycle characteristics were collected. X-chromosome inactivation (XCI) was measured using a human AR assay. AR polymorphisms were assessed using quantitative fluorescent polymerase chain reactions and direct sequencing. Blastocysts of the patients with RPL were tested by single nucleotide polymorphism microarray based preimplantation genetic testing for aneuploidy.

RESULTS

In total, 131 patients with idiopathic RPL and 126 controls were included for the case-control study. Patients with RPL exhibited a significantly more skewed XCI distribution pattern (67.71 ± 10.50 vs. 64.22 ± 10.62, p = 0.011), as well as significantly shorter bi-allelic mean (18.56 ± 1.97 vs. 19.34 ± 2.38, p = 0.005) and X-weighted bi-allelic mean (18.46 ± 2.02 vs. 19.38 ± 2.53, p = 0.001) of AR CAG repeats. Multivariate logistic regression models indicated that CAG repeat < 20, SXCI, and duration of stimulation were independently associated with the risk of RPL. However, SXCI and AR CAG polymorphisms were not associated with ovarian reserve or preimplantation embryo aneuploidy in the RPL group, and the same results were attained in a separate validation cohort of 363 patients with RPL.

CONCLUSION

SXCI and AR CAG polymorphisms are related to RPL; however, these two factors do not lead to RPL by affecting the ovarian reserve or increasing embryo aneuploidy. The roles of SXCI and AR CAG in RPL may involve other mechanisms that require further investigation.

TRIAL REGISTRATION

NCT02504281, https://www.

CLINICALTRIALS

gov (Date of registration, 21/07/2015; date of enrolment of the first subject, 30/07/2015).

In vitro growth (IVG) of human ovarian follicles in frozen thawed ovarian cortex tissue culture supplemented with follicular fluid under hypoxic conditions

Background

Despite its clinical success rates, transplantation after ovarian tissue cryopreservation (OTC) remains a matter of concern. Certain cancer subtypes may lead to the transfer of malignant cells when transplantation of affected ovarian tissue is conducted. IVG and subsequent isolation of vital follicles obtained from frozen thawed ovarian tissue for further in vitro maturation (IVM) would expand current fertility protection techniques while reducing the risk of retransplanting malignant cells.

Methods

A total of 216 cortical biopsies from 3 patients were included in this study in 4 treatment groups. After freezing, thawing and 8 days of hypoxic tissue culture supplemented with different concentrations of human follicular fluid (HuFF) and follicle-stimulating hormone (FSH), follicles were isolated enzymatically and stained with calcein to determine follicular viability. Numbers and size of vital follicles were assessed by fluorescence microscopy (Ti2, Nikon) and specified by computer assisted, semi-automated measurement (NIS software, Nikon). To estimate the effect of in vitro culture on apoptosis, tissue sections were stained for nicked DNA (TUNEL) prior and after tissue culture.

Results

Analysing 3025 vital follicles, we observed significant differences [P < 0.01] regarding follicle size when hypoxic tissue culture was supplemented with HuFF compared with the control group on day 1, individual follicles reached sizes > 100 µm.

Conclusions

The results implicate that HuFF contains valuable factors contributing to significant IVG of follicles in human ovarian tissue and could be regarded as an additional tool in personalized fertility restoration prior to retransplantation of ovarian tissue.

Regulation of antral follicular growth by an interplay between gonadotropins and their receptors

Knowledge of the growth and maturation of human antral follicles is based mainly on concepts and deductions from clinical observations and animal models. To date, new experimental approaches and in vitro data contributed to a deep comprehension of gonadotropin receptors' functioning and may provide new insights into the mechanisms regulating still unclear physiological events. Among these, the production of androgen in the absence of proper LH levels, the programming of follicular atresia and dominance are some of the most intriguing. Starting from evolutionary issues at the basis of the gonadotropin receptor signal specificity, we draw a new hypothesis explaining the molecular mechanisms of the antral follicular growth, based on the modulation of endocrine signals by receptor-receptor interactions. The "heteromer hypothesis" explains how opposite death and life signals are delivered by gonadotropin receptors and other membrane partners, mediating steroidogenesis, apoptotic events, and the maturation of the dominant follicle.

Transcriptomic profiling of neonatal mouse granulosa cells reveals new insights into primordial follicle activation†

The dormant population of ovarian primordial follicles is determined at birth and serves as the reservoir for future female fertility. Yet our understanding of the molecular, biochemical, and cellular processes underpinning primordial follicle activation remains limited. The survival of primordial follicles relies on the correct complement and morphology of granulosa cells, which provide signaling factors essential for oocyte and follicular survival. To investigate the contribution of granulosa cells in the primordial-to-primary follicle transition, gene expression profiles of granulosa cells undergoing early differentiation were assessed in a murine model. Ovaries from C57Bl/6 mice were enzymatically dissociated at time-points spanning the initial wave of primordial follicle activation. Post-natal day (PND) 1 ovaries yielded primordial granulosa cells, and PND4 ovaries yielded a mixed population of primordial and primary granulosa cells. The comparative transcriptome of granulosa cells at these time-points was generated via Illumina NextSeq 500 system, which identified 131 significantly differentially expressed transcripts. The differential expression of eight of the transcripts was confirmed by RT-qPCR. Following biological network mapping via Ingenuity Pathway Analysis, the functional expression of the protein products of three of the differentially expressed genes, namely FRZB, POD1, and ZFX, was investigated with in-situ immunolocalization in PND4 mouse ovaries was investigated. Finally, evidence was provided that Wnt pathway antagonist, secreted frizzled-related protein 3 (FRZB), interacts with a suppressor of primordial follicle activation WNT3A and may be involved in promoting primordial follicle activation. This study highlights the dynamic changes in gene expression of granulosa cells during primordial follicle activation and provides evidence for a renewed focus into the Wnt signaling pathway’s role in primordial follicle activation.

Ovarian tissue damage after grafting: systematic review of strategies to improve follicle outcomes

Frozen-thawed human ovarian tissue endures large-scale follicle loss in the early post-grafting period, characterized by hypoxia lasting around 7 days. Tissue revascularization occurs progressively through new vessel invasion from the host and neoangiogenesis from the graft. Such reoxygenation kinetics lead to further potential damage caused by oxidative stress. The aim of the present manuscript is to provide a systematic review of proangiogenic growth factors, hormones and various antioxidants administered in the event of ovarian tissue transplantation to protect the follicle pool from depletion by boosting revascularization or decreasing oxidative stress. Although almost all investigated studies revealed an advantage in terms of revascularization and reduction in oxidative stress, far fewer demonstrated a positive impact on follicle survival. As the cascade of events driven by ischaemia after transplantation is a complex process involving numerous players, it appears that acting on specific molecular mechanisms, such as concentrations of proangiogenic growth factors, is not enough to significantly mitigate tissue damage. Strategies exploiting the activated tissue response to ischaemia for tissue healing and remodelling purposes, such as the use of antiapoptotic drugs and adult stem cells, are also discussed in the present review, since they yielded promising results in terms of follicle pool protection.

Notch signaling pathway in cumulus cells reflecting zygote and embryo quality in polycystic ovary syndrome

PURPOSE

The present study aimed to explore the associations between the expression pattern of molecules in the Notch pathway in the cumulus cells of polycystic ovary syndrome (PCOS) patients and the quality of zygotes and embryos.

METHODS

A total of 200 cumulus complexes surrounding mature oocytes were obtained from 40 patients with and without PCOS undergoing intracytoplasmic sperm injection (ICSI). The expressions of Notch-1, Notch-2, and Notch-3 genes were examined by Reverse Transcription Q-PCR assay. Moreover, immunocytochemistry was performed for the expressions of Jagged-1 and Jagged-2 proteins. The correlations between the Notch receptors and their ligand expressions and the qualities of the zygote and embryo were investigated.

RESULTS

The expression levels of Notch-2, Notch-3, Jagged-1, and Jagged-2 were significantly lower in patients with PCOS than in normal women (p < 0.05), while Notch-1 showed no meaningful difference between the groups. A positive correlation was found between Notch-1 and embryo quality. Furthermore, only Notch-2 and Jagged-2 marginally correlated with zygote quality.

CONCLUSION

The data of the present study indicated that evaluating the molecules in the Notch pathway in PCOS patients' cumulus cells provides a novel approach to predict the zygote and embryo quality. However, further studies on a larger population are needed to validate this finding.

Exosomal miR-27 negatively regulates ROS production and promotes granulosa cells apoptosis by targeting SPRY2 in OHSS

Ovarian hyperstimulation syndrome (OHSS) is one of the most dangerous iatrogenic complications in controlled ovarian hyperstimulation (COH). The exact molecular mechanism that induces OHSS remains unclear. In recent years, accumulating evidence found that exosomal miRNAs participate in many diseases of reproductive system. However, the specific role of miRNAs, particularly the follicular fluid-derived exosomal miRNAs in OHSS remains controversial. To identify differentially expressed follicular fluid exosomal miRNAs from OHSS and non-OHSS patients, the analysis based on miRNA-sequence was conducted. The levels of 291 miRNAs were significantly differed in exosomes from OHSS patients compared with normal control, and exosomal miR-27 was one of the most significantly down-regulated miRNAs in the OHSS group. By using MiR-27 mimic, we found it could increase ROS stress and apoptosis by down-regulating the expression of p-ERK/Nrf2 pathway by negatively regulating SPRY2. These data demonstrate that exosomal miRNAs are differentially expressed in follicular fluid between patients with and without OHSS, and follicular fluid exosomal miR-27 may involve in the pathological process of OHSS development.

A role for orphan nuclear receptor liver receptor homolog-1 (LRH-1, NR5A2) in primordial follicle activation

Liver receptor homolog-1 (NR5A2) is expressed specifically in granulosa cells of developing ovarian follicles where it regulates the late stages of follicle development and ovulation. To establish its effects earlier in the trajectory of follicular development, NR5A2 was depleted from granulosa cells of murine primordial and primary follicles. Follicle populations were enumerated in neonates at postnatal day 4 (PND4) coinciding with the end of the formation of the primordial follicle pool. The frequency of primordial follicles in PND4 conditional knockout (cKO) ovaries was greater and primary follicles were substantially fewer relative to control (CON) counterparts. Ten-day in vitro culture of PND4 ovaries recapitulated in vivo findings and indicated that CON mice developed primary follicles in the ovarian medulla to a greater extent than did cKO animals. Two subsets of primordial follicles were observed in wildtype ovaries: one that expressed NR5A2 and the second in which the transcript was absent. Neither expressed the mitotic marker. KI-67, indicating their developmental quiescence. RNA sequencing on PND4 demonstrated that loss of NR5A2 induced changes in 432 transcripts, including quiescence markers, inhibitors of follicle activation, and regulators of cellular migration and epithelial-to-mesenchymal transition. These experiments suggest that NR5A2 expression poises primordial follicles for entry into the developing pool.

Functional Gene Expression Differentiation of the Notch Signaling Pathway in Female Reproductive Tract Tissues-A Comprehensive Review With Analysis

The Notch pathway involves evolutionarily conserved signaling regulating the development of the female tract organs such as breast, ovary, cervix, and uterine endometrium. A great number of studies revealed Notch aberrancies in association with their carcinogenesis and disease progression, the management of which is still challenging. The present study is a comprehensive review of the available literature on Notch signaling during the normal development and carcinogenesis of the female tract organs. The review has been enriched with our analyses of the TCGA data including breast, cervical, ovarian, and endometrial carcinomas concerning the effects of Notch signaling at two levels: the core components and downstream effectors, hence filling the lack of global overview of Notch-driven carcinogenesis and disease progression. Phenotype heterogeneity regarding Notch signaling was projected in two uniform manifold approximation and projection algorithm dimensions, preceded by the principal component analysis step reducing the data burden. Additionally, overall and disease-free survival analyses were performed with the optimal cutpoint determination by Evaluate Cutpoints software to establish the character of particular Notch components in tumorigenesis. In addition to the review, we demonstrated separate models of the examined cancers of the Notch pathway and its targets, although expression profiles of all normal tissues were much more similar to each other than to its cancerous compartments. Such Notch-driven cancerous differentiation resulted in a case of opposite association with DFS and OS. As a consequence, target genes also show very distinct profiles including genes associated with cell proliferation and differentiation, energy metabolism, or the EMT. In conclusion, the observed Notch associations with the female tract malignancies resulted from differential expression of target genes. This may influence a future analysis to search for new therapeutic targets based on specific Notch pathway profiles.

Insulin-like growth factor 2 is produced by antral follicles and promotes preantral follicle development in macaques†

Insulin-like growth factors (IGFs) are known for their involvement in endocrine and paracrine regulation of ovarian function. Although IGF2 is the predominant circulating and intraovarian form of IGFs in primate species, the stage-specific follicular expression, action, and regulation of IGF2 are not well defined. Therefore, experiments were conducted to investigate the follicular IGF production in response to steroid hormone regulation and the direct IGF actions on follicular development and function in vitro. Preantral follicles were isolated from rhesus macaque ovaries and cultured to the antral stage in media supplemented with follicle-stimulating hormone and insulin. Follicles were randomly assigned to treatment groups: (a) control, (b) trilostane (a steroid synthesis inhibitor), (c) trilostane + estradiol, (d) trilostane + progesterone, and (e) trilostane + dihydrotestosterone. Media was analyzed for IGF concentrations, which were correlated to follicle growth. Follicles produced IGF2, but not IGF1, at the antral stage. Steroid depletion decreased, whereas steroid replacement increased, IGF2 production by antral follicles. Media IGF2 levels correlated positively with antral follicle diameters. Macaque preantral follicles and granulosa cells were subsequently cultured without (control) and with recombinant human IGF2 supplementation. Follicle survival, growth, and paracrine factor production, as well as granulosa cell proliferation and gonadotropin receptor gene expression, were assessed. IGF2 addition increased follicle survival rates, diameters and inhibin B production, as well as granulosa cell proliferation. These data demonstrate that IGF2 produced by antral follicles, in response to steroid hormone regulation, could act as a paracrine factor that positively impacts preantral follicle development and function in primates.

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.

Ultrastructure and intercellular contact-mediated communication in cultured human early stage follicles exposed to mTORC1 inhibitor

The reproductive lifespan of a woman is determined by the gradual recruitment of quiescent follicles into the growing pool. In humans, ovarian tissue removal from its in vivo environment induces spontaneous activation of resting follicles. Similarly, pharmacological activation of the PI3K/Akt pathway leads to accelerated follicle recruitment, but has been associated with follicular damage. Recent findings demonstrate that everolimus (EVE), an mTORC1 inhibitor, limits primordial follicle activation. However, its potential benefit regarding growing follicle integrity remains unexplored. Ovarian cortical fragments were exposed to ± EVE for 24 h and cultured for an additional 5 days. After 0, 1 and 6 days of culture, fragments were either processed for ultrastructural analysis or subjected to follicular isolation for gene expression and immunofluorescence assessments. Data from transmission electron microscopy showed that growing follicles displayed similar ultrastructural features irrespective of the conditions and maintained close contacts between germinal and stromal compartments. Establishment of intra-follicular communication was confirmed by detection of a gap junction component, Cx43, in both groups throughout culture, whereas transzonal projections, which physically link granulosa cells to oocyte, formed later in EVE-treated follicles. Importantly, levels of GJA1 mRNA, encoding for the Cx43 protein, significantly increased from Day 0 to Day 1 in the EVE group, but not in the control group. Given that EVE-treated follicles were smaller than controls, these findings suggest that EVE might facilitate the establishment of appropriate intercellular communications without impairing follicle ultrastructure. Therefore, mTORC1 inhibitors might represent an attractive tool to delay the culture-induced primordial follicle activation while maintaining follicles in a functionally integrated state.

FertiPROTEKT, Oncofertility Consortium and the Danish Fertility-Preservation Networks - What Can We Learn From Their Experiences?

Fertility preservation is an increasingly important discipline. It requires close coordination between reproductive medicine specialists, reproductive biologists, and oncologists in various disciplines. In addition, it represents a particular health policy challenge, since fertility-protection measures are to be understood as a treatment for side effects of gonadotoxic treatments and would therefore normally have to be reimbursed by health insurance companies. Therefore, it is inevitable that fertility-preservation activities should organise themselves into a network structure both as a medical-logistic network and as a professional medical society. The necessary network structures can differ significantly at regional, national, and international level, as the size of the regions to be integrated and the local cultural and geographical conditions, as well as the political conditions are very different. To address these issues, the current review aims to point out the basic importance and the chances but also the difficulties of fertility-protection networks and give practical guidance for the development of such network structures. We will not only discuss network structures theoretically but also present them based on three established, different sized networks, such as the Danish Network (www.rigshospitalet.dk), representing a centralised network in a small country; the German-Austrian-Swiss network FertiPROTEKT® (www.fertiprotekt.com), representing a centralised as well as decentralised network in a large country; and the Oncofertility® Consortium (www.oncofertility.northwestern.edu), representing a decentralised, internationally oriented network, primarily serving the transfer of knowledge among its members.

Persistent epigenetic changes in adult daughters of older mothers

Women of advanced maternal age account for an increasing proportion of live births in many developed countries across the globe. Offspring of older mothers are at an increased risk for a variety of subsequent health outcomes, including outcomes that do not manifest until childhood or adulthood. The molecular underpinnings of the association between maternal aging and offspring morbidity remain elusive. However, one possible mechanism is that maternal aging produces specific alterations in the offspring's epigenome in utero, and these epigenetic alterations persist into adulthood. We conducted an epigenome-wide association study (EWAS) of the effect of a mother's age on blood DNA methylation in 2,740 adult daughters using the Illumina Infinium HumanMethylation450 array. A false discovery rate (FDR) q-value threshold of 0.05 was used to identify differentially methylated CpG sites (dmCpGs). We identified 87 dmCpGs associated with increased maternal age. The majority (84%) of the dmCpGs had lower methylation in daughters of older mothers, with an average methylation difference of 0.6% per 5-year increase in mother's age. Thirteen genomic regions contained multiple dmCpGs. Most notably, nine dmCpGs were found in the promoter region of the gene LIM homeobox 8 (LHX8), which plays a pivotal role in female fertility. Other dmCpGs were found in genes associated with metabolically active brown fat, carcinogenesis, and neurodevelopmental disorders. We conclude that maternal age is associated with persistent epigenetic changes in daughters at genes that have intriguing links to health.

Transcription profile of the insulin-like growth factor signaling pathway during human ovarian follicular development

PURPOSE

The IGF signaling cascade exerts important regulatory functions in human ovarian folliculogenesis. The scope of this study was to evaluate the transcription profile of insulin-like growth factor (IGF) genes during human ovarian follicle development and to analyze follicle fluid levels of key IGF proteins.

METHODS

Gene expression profiling was performed with microarray gene analysis. The analysis was assessed from ovarian follicles and granulosa cells (GCs) obtained from isolated stage-specific human ovarian follicles, including preantral follicles, small antral follicles, and preovulatory follicles. Numerous genes involved in the IGF signaling pathway was evaluated and key genes were validated by qPCR from GCs. Protein levels of various IGF components of human follicular fluid (FF) were measured by ELISA and time-resolved immunofluorometric assays (TRIFMA).

RESULTS

The gene expression levels of PAPPA, IGF2, IGF receptors and intracellular IGF-activated genes increased with increasing follicle size. This was especially prominent in the late preovulatory stage where IGF2 expression peaked. Protein levels of intact IGF binding protein-4 decreased significantly in FF from large preovulatory follicles compared with small antral follicles concomitant with higher protein levels of PAPP-A. The IGF modulators IGF-2 receptor, IGFBPs, stanniocalcins, and IGF-2 mRNA binding proteins were all observed to be expressed in the different follicle stages.

CONCLUSIONS

This study confirms and highlights the importance of PAPP-A regulating bioactive IGF levels throughout folliculogenesis and especially for the high rate of granulosa cell proliferation and expression of key ovarian hormones important in the last part of the follicular phase of the menstrual cycle.

Granulosa cells from human primordial and primary follicles show differential global gene expression profiles

STUDY QUESTION

Can novel genetic candidates involved in follicle dormancy, activation and integrity be identified from transcriptomic profiles of isolated granulosa cells from human primordial and primary follicles?

SUMMARY ANSWER

The granulosa cell compartment of the human primordial and primary follicle was extensively enriched in signal transducer and activator of transcription 3 (STAT3) and cAMP-response element binding protein (CREB) signalling, and several other putative signalling pathways that may also be mediators of follicle growth and development were identified.

WHAT IS KNOWN ALREADY

Mechanistic target of rapamycin kinase (mTOR) signalling and the factors Forkhead Box L2 (FOXL2) and KIT proto-oncogene receptor tyrosine kinase (KITL) may be involved in defining the early steps of mammalian follicular recruitment through complex bidirectional signalling between the oocyte and granulosa cells. cAMP/protein kinase K (PKA)/CREB signalling is a feature of FSH-induced regulation of granulosa cell steroidogenesis that is essential to normal human fertility.

STUDY DESIGN, SIZE, DURATION

A class comparison study was carried out on primordial follicles (n = 539 follicles) and primary follicles (n = 261) follicles) donated by three women having ovarian tissue cryopreserved before chemotherapy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA samples from isolates of laser capture micro-dissected oocytes and follicles from the primordial and primary stage, respectively, were sequenced on the HiSeq Illumina platform. Data mapping, quality control, filtering, FPKM (fragments per kilobase of exon per million) normalization and comparisons were performed. The granulosa cell contribution in whole follicle isolates was extracted in silico. Modelling of complex biological systems was performed using Ingenuity Pathway Analysis (IPA). For validation of transcriptomic findings, we performed quantitative RT-PCR of selected candidate genes. Furthermore, we interrogated the in situ localization of selected corresponding proteins using immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

Our differentially expressed gene analysis revealed a number of transcripts in the granulosa cells to be significantly down- (736 genes) or up- (294 genes) regulated during the human primordial-to-primary follicle transition. The IPA analysis revealed enriched canonical signalling pathways not previously associated with granulosa cells from human primordial and primary follicles. Immunofluorescent staining of human ovarian tissue explored the intra-ovarian localization of FOG2, and FOXL2, which revealed the presence of forkhead box L2 (FOXL2) in both oocytes and granulosa cells in primary follicles, with a more enriched staining in the granulosa cells in primary follicles. Friend of GATA 2 (FOG2) stained strongly in oocytes in primordial follicles, with a shift towards granulosa cell as follicle stage advanced.

LARGE SCALE DATA

http://users-birc.au.dk/biopv/published_data/ernst_et_al_GC_2017/.

LIMITATIONS REASONS FOR CAUTION

This is a descriptive study, and no functional assays were employed. The study was based on a limited number of patients, and it is acknowledged that natural biological variance exists in human samples. Strict filters were applied to accommodate the in silico extraction of the granulosa cell contribution. In support of this, quantitative RT-PCR was used to confirm selected candidate genes, and immunofluorescent staining was employed to interrogate the intra-ovarian distribution of selected corresponding proteins. Moreover, it is unknown whether the primordial follicles analysed represent those still in the resting pool, or those from the cohort that have entered the growing pool.

WIDER IMPLICATIONS OF THE FINDINGS

We present, for the first time, a detailed description of global gene activity in the human granulosa cell compartment of primordial and primary follicles. These results may be utilized in the development of novel clinical treatment strategies aimed at improving granulosa cell function.

STUDY FUNDING/COMPETING INTEREST(S)

E.H.E. was supported by the Health Faculty, Aarhus University and Kong Christian Den Tiendes Fond. K.L.H. was supported by a grant from Fondens til Lægevidenskabens Fremme and Kong Christian Den Tiendes Fond. No authors have competing interests to declare.

Functional evidence implicating NOTCH2 missense mutations in primary ovarian insufficiency etiology

Primary ovarian insufficiency (POI) is a frequently occurring disease affecting women under 40 years old. Recently, we have analyzed unrelated POI women via whole exome sequencing (WES) and identified NOTCH2 mutations underlying possible functional effects. The present study involved reanalyzing of WES assays. We used in the KGN granulosa-like cell model, a synthetic gene reporter construct driving luciferase gene expression to assess the functional effects of five NOTCH2 mutations identified in POI patients. We found that NOTCH2-p.Ser1804Leu, p.Ala2316Val, and p.Pro2359Ala mutations had a functional impact on the protein's transcriptional activity. The results have demonstrated for the first time that NOTCH2 mutations contribute to POI etiology. We therefore recommend sequencing NOTCH2's open reading frame in large panels of POI patients to establish an accurate genotype-phenotype correlation. We cannot rule out the fact that patients affected by Alagille syndrome carrying NOTCH2 mutations may suffer ovarian dysfunction.

Variants in the CYP19A1 gene can affect in vitro embryo production traits in cattle

PURPOSE

This study aimed to associate DNA variants in promoter and exon flanking regions of the CYP19A1 gene with in vitro embryo production traits in cattle. The role of transcription factor binding sites created or lost due to DNA sequence variation and their possible effect on gene expression was also evaluated.

METHODS

We collected date from Gyr dairy oocyte donor cows (Bos taurus indicus) at a commercial in vitro embryo production farm and analyzed the genotype-phenotype association with in vitro production traits. Using Sanger sequencing and web-based software, we assessed important CYP19A1 gene regions in oocyte donor cows and analyzed the effects of variants on the transcription factor binding sites.

RESULTS

Two SNP mutations significantly associated with oocyte production, oocyte viability, embryo development, and pregnancies were found (T > C in the untranslated exon 1 flanking region ([GenBank: AJ250379.1]: rs718446508 T > C), and a T > C in the 5'-upstream region (1.1 promoter) ([GenBank: AC_000167.1]: rs41651668 T > C). Six new transcription factor binding sites were created. A binding site for transcription factors associated with the development of the placenta and embryo implantation was eliminated due to variations in the DNA sequence identified.

CONCLUSIONS

The CYP19A1 gene contributes to genetic variation of in vitro embryo production traits in cattle. The complexity of the physiological phenomena related to estrogen pathways and their influence on reproduction in cattle allow indication of the mutations evaluated here as possible genetic markers for embryo production traits, which should be validated in the next steps of marker-assisted selection.

Comparative profiling of differentially expressed microRNAs in estrous ovaries of Kazakh sheep in different seasons

Seasonal estrus is a critical limiting factor for animal fecundity. However, estrus occurs in some seasonally estrous sheep in the non-breeding season, and this phenomenon involves changes in ovarian biology. Previous studies indicated that small RNAs, such as microRNAs (miRNAs), play important regulatory roles in ovarian biology. Differentially expressed miRNAs in the ovaries of estrous sheep were identified using Solexa sequencing technology. A total of 423 known miRNAs were identified in ovaries of estrous sheep in the breeding season and non-breeding season. In the comparison of these two groups, 48 miRNAs were identified that were differentially expressed between the two groups (including 5 up-regulated and 43 down-regulated miRNAs). KEGG pathway analysis revealed that the target genes of some differentially expressed miRNAs were involved in pathways related to reproductive hormone signaling and follicular development. Furthermore, the levels of estradiol (E2), progesterone (P4), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were lower in anestrus sheep than in sheep during the breeding season. Upon combining the pathway enrichment analysis, target gene expression and hormone measurement results, we suggest that these differentially expressed miRNAs might influence ovarian activity in the non-breeding season by regulating the above pathways. The identification of miRNAs that are differentially expressed between ovines in the breeding season and non-breeding season will contribute to our understanding of the role of miRNAs in estrus regulation, and these data may provide a basis for regulating estrus in sheep during the non-breeding season.

Cryopreservation of Ovarian Tissue: Opportunities Beyond Fertility Preservation and a Positive View Into the Future

In current years, ovarian tissue cryopreservation (OTC) and transplantation is gaining ground as a successful method of preserving fertility in young women with primarily cancer diseases, hereby giving them a chance of becoming biological mothers later on. However, OTC preserves more than just the reproductive potential; it restores the ovarian endocrine function and thus the entire female reproductive cycle with natural levels of essential hormones. In a female population with an increased prevalence in the loss of ovarian function due to induced primary ovarian insufficiency (POI) and aging, there is now, a need to develop new treatments and provide new opportunities to utilize the enormous surplus of follicles that most females are born with and overcome major health issues associated with the lack of ovarian hormones. Cell/tissue-based hormone replacement therapy (cHRT) by the use of stored ovarian tissue could be one such option comprising both induction of puberty in prepubertal POI girls, treatment of POI and premature menopause, and as primary prevention at the onset of menopause. In the current review, we explore known and entirely new applications for the potential utilization of OTC including cHRT, social freezing, culture of immature oocytes, and a modern ovarian resection for women with polycystic ovaries, and discuss the indications hereof.

The Orphan Nuclear Receptor Liver Homolog Receptor-1 (Nr5a2) Regulates Ovarian Granulosa Cell Proliferation

In mouse ovaries, liver receptor homolog-1 [nuclear receptor subfamily 5, group A, member 2 (Nr5a2)] expression is restricted to granulosa cells. Mice with Nr5a2 depletion in this cell population fail to ovulate. To determine whether Nr5a2 is essential for granulosa cell proliferation during follicular maturation, we generated granulosa-specific conditional knockout mice (genotype Nr5a2 floxed Cre-recombinase driven by the anti-Müllerian type II receptor, hereafter cKO) with Nr5a2 depletion from primary follicles forward. Proliferation in cKO granulosa cells was substantially reduced relative to control (CON) counterparts, as assessed by bromodeoxyuridine incorporation, proliferative cell nuclear antigen expression, and fluorescent-activated cell sorting. Microarray analysis revealed >2000 differentially regulated transcripts between cKO and CON granulosa cells. Major gene ontology pathways disrupted were proliferation, steroid biosynthesis, female gamete formation, and ovulatory cycle. Transcripts for key cell-cycle genes, including Ccnd1, Ccnd2, Ccne1, Ccne2, E2f1, and E2f2, were in reduced abundance. Transcripts from other cell-cycle-related factors, including Cdh2, Plagl1, Cdkn1a, Prkar2b, Gstm1, Cdk7, and Pts, were overexpressed. Although the follicle-stimulating hormone and estrogen receptors were overexpressed in the cKO animals, in vivo treatment with estradiol-17β failed to rescue decreased proliferation. In vitro inactivation of Nr5a2 using the ML180 reverse agonist similarly decreased cell-cycle-related gene transcripts and downstream targets, as in cKO mice. Pharmacological inhibition of β-catenin, an Nr5a2 cofactor, decreased cyclin gene transcripts and downstream targets. Terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling immunofluorescence and quantitative polymerase chain reaction of pro/antiapoptotic and autophagic markers showed no differences between cKO and CON granulosa cells. Thus, Nr5a2 is essential for granulosa cell proliferation, but its depletion does not alter the frequency of apoptosis nor autophagy.

Dormancy and activation of human oocytes from primordial and primary follicles: molecular clues to oocyte regulation

STUDY QUESTION

Do specific transcriptome dynamics in human oocytes from primordial and primary follicles identify novel pathways in oocyte activation?

SUMMARY ANSWER

The transcriptomic profiles in oocytes from primordial and primary follicles, respectively, revealed several new canonical pathways as putative mediators of oocyte dormancy and activation.

WHAT IS KNOWN ALREADY

Cellular signaling pathways including PI3K/AKT and AKT/mTOR as well as TGF-β and IGF signaling are known to regulate the primordial-to-primary transition in mammalian follicle development.

STUDY DESIGN, SIZE, DURATION

We performed a class comparison study on human oocytes from primordial (n = 436) and primary (n = 182) follicles donated by three women having ovarian tissue cryopreserved before chemotherapy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA was extracted from oocytes from primordial and primary follicles isolated by Laser Capture Microdissection, and submitted to the HiSeq Illumina platform. Data mapping, quality control, filtering and expression analysis were performed using Tophat (2.0.4), Cufflinks (2.0.2), BWA (0.6.2) and software R. Modeling of complex biological systems was performed using the IPA® software. Finally, qPCR and immunohistochemistry were employed to explore expression and localization of selected genes and products in human ovarian tissue.

MAIN RESULTS AND THE ROLE OF CHANCE

We found 223 and 268 genes down-regulated and up-regulated, respectively, in the oocytes during the human primordial-to-primary follicle transition (P < 0.05 and/or FPKM fold-change >2). IPA® enrichment analysis revealed known pathways ('mTOR Signaling', 'PI3K/AKT Signaling' and 'PTEN Signaling') as well as enriched canonical pathways not previously associated with human ovarian follicle development such as 'ErB Signaling' and 'NGF Signaling' in the down-regulated category and 'Regulation of eIF4 and P70S6K Signaling' and 'HER-2 Signaling in Breast Cancer' in the up-regulated group. Additionally, immunohistochemistry on human ovarian tissue explored the intraovarian localization of VASA, FOXO1 and eIF4E.

LARGE SCALE DATA

http://users-birc.au.dk/biopv/published_data/ernst_2017/.

LIMITATIONS, REASONS FOR CAUTION

This is a descriptive analysis and no functional studies were performed. The study was based on a limited number of patients and the experimental design could not take into account the natural biological variance in human samples. Therefore, qPCR was used to confirm selected genes alongside immunohistochemical stainings.

WIDER IMPLICATIONS OF THE FINDINGS

This study shows, for the first time, a detailed molecular description of global gene transcription activities in oocytes from primordial and primary follicles, respectively. Knowing the global transcription profiles of human oocyte dormancy and activation are important in developing new clinical applications.

STUDY FUNDING/COMPETING INTEREST(S)

E.H.E. was supported by Health Faculty, Aarhus University and Kong Christian Den Tiendes Fond. K.H. and S.F. were supported by an MRC (UK) project grant MR/M012638/1. K.L.H. was supported by grants from Fonden til Lægevidenskabens Fremme, Kong Christian Den Tiendes Fond. K.L.H. and L.S. were supported by the IDEAS grant from Aarhus University Research Foundation (AUFF). There are no conflicts of interest.

The role of Notch signaling in the mammalian ovary

The Notch pathway is a contact-dependent, or juxtacrine, signaling system that is conserved in metazoan organisms and is important in many developmental processes. Recent investigations have demonstrated that the Notch pathway is active in both the embryonic and postnatal ovary and plays important roles in events including follicle assembly and growth, meiotic maturation, ovarian vasculogenesis and steroid hormone production. In mice, disruption of the Notch pathway results in ovarian pathologies affecting meiotic spindle assembly, follicle histogenesis, granulosa cell proliferation and survival, corpora luteal function and ovarian neovascularization. These aberrations result in abnormal folliculogenesis and reduced fertility. The knowledge of the cellular interactions facilitated by the Notch pathway is an important area for continuing research, and future studies are expected to enhance our understanding of ovarian function and provide critical insights for improving reproductive health. This review focuses on the expression of Notch pathway components in the ovary, and on the multiple functions of Notch signaling in follicle assembly, maturation and development. We focus on the mouse, where genetic investigations are possible, and relate this information to the human ovary.

The Common Follicle-Stimulating Hormone Receptor (FSHR) Promoter Polymorphism FSHR -29G > A Affects Androgen Production in Normal Human Small Antral Follicles

Follicle-stimulating hormone receptors (FSHRs) are almost exclusively expressed on granulosa cells, and FSH action is probably most clearly reflected in intrafollicular hormone milieu of antral follicles. Little is known about the possible effects of the common single nucleotide polymorphism (SNP) FSHR -29G > A (rs1394205) on hormonal conditions in humsan small antral follicles (hSAFs) obtained from women in the natural menstrual cycle. This study investigated the follicle fluid (FF) concentrations of anti-Müllerian hormone, estradiol, progesterone, androstenedione, and testosterone in hSAF in relation to the different genotypes of FSHR -29G > A. FF from 362 follicles was collected in 95 women undergoing fertility preservation, who did not suffer from a disease that directly affected ovarian function. The testosterone levels of the minor A/A genotype were significantly increased compared to the A/G and the G/G genotype. Furthermore, significantly reduced androstenedione levels were observed for the G/G genotype, as compared to the A/G genotype, while the other hormones did not show statistical significant differences. In conclusion, the androgen levels of hSAF were significantly elevated in the minor SNP genotype in the FSHR promoter polymorphism FSHR -29G > A.

Connexin 37 and 43 gene and protein expression and developmental competence of isolated ovine secondary follicles cultured in vitro after vitrification of ovarian tissue

Cryoinjuries caused by vitrification of tissues and organs lead to the loss of membrane proteins that mediate intercellular communications, such as connexins 37 (Cx37) and 43 (Cx43). Thus, the present study aimed to evaluate ovine Cx37 and Cx43 gene and protein expressions and developmental competence by in vitro-cultured secondary follicles retrieved from vitrified ovarian tissue. Ovarian fragments for the same ovary pair were distributed into six treatments: (1) fresh ovarian tissue (FOT); (2) vitrified ovarian tissue (VOT); (3) isolated follicles from fresh ovarian tissue (FIF); (4) isolated follicles from vitrified ovarian tissue; (5) isolated follicles from fresh ovarian tissue followed by in vitro culture (CFIF); (6) isolated follicles from vitrified ovarian tissue followed by in vitro culture (CVIF). In all treatments, Cx37 and Cx43 gene and protein expression patterns were evaluated by reverse transcription polymerase chain reaction and immunocytochemistry. In addition, secondary follicles were analyzed according to follicular integrity and growth, apoptosis, and cell proliferation. In vitro-cultured secondary follicles (CFIF and CVIF) were evaluated based on morphology (extruded follicles), antrum formation, and viability. The percentage of intact follicles was higher, whereas antrum formation, oocyte extrusion rate, and follicle viability were lower in CVIF than in CFIF treatment (P < 0.05). Terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling assay demonstrated that apoptosis was absent in FIF, whereas follicles from all other treatments showed positive labeling. Cell proliferation index was higher in isolated follicles from vitrified ovarian tissue and CVIF treatments than in follicles from FIF. Expression of Cx43 messenger RNA was lower in CVIF treatment when compared with follicles from all other treatments (P < 0.05). Follicle Cx37 messenger RNA levels did not show alterations in any treatment (P > 0.05). Cx37 and Cx43 immunolabeling was localized mainly on granulosa cells and oocytes, respectively. In conclusion, isolation of ovine secondary follicles could be done successfully after vitrification of ovarian tissue, and the basement membrane integrity remained intact after in vitro culture. Although the gene and protein expression of Cx37 did not change after vitrification of ovarian tissue, Cx43 turned out to be altered in secondary follicles after vitrification and in vitro culture.

Genetic variations altering FSH action affect circulating hormone levels as well as follicle growth in healthy peripubertal girls

STUDY QUESTION

Do variants of the genes encoding follicle stimulating hormone (FSH) beta subunit (B) and FSH receptor (R) impact circulating reproductive hormone levels and ovarian follicle maturation in healthy peripubertal girls?

SUMMARY ANSWER

FSHB and FSHR genetic variants exert, alone or their combination, distinct effects on reproductive hormone levels as well as ovarian follicle maturation in healthy peripubertal girls.

WHAT IS KNOWN ALREADY

FSHB and FSHR genetic variants impact reproductive hormone levels as well as associated pathologies in women. While FSHR c. 2039A>G is known to alter gonadotrophin levels in women, FSHR c.-29G>A has not yet been shown to exert effect and there are conflicting results concerning FSHB c.-211G>T.

STUDY DESIGN, SIZE, DURATION

This population-based study included 633 girls recruited as part of two cohorts, the COPENHAGEN Puberty Study (2006-2014, a cross-sectional and ongoing longitudinal study) and the Copenhagen Mother-Child Cohort (1997-2002, including transabdominal ultrasound (TAUS) of the ovaries in a subset of 91 peripubertal girls).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Clinical examinations, including pubertal breast stage (Tanner's classification B1-B5) were performed. Circulating levels of FSH, luteinizing hormone (LH), estradiol, anti-Mullerian hormone (AMH) and inhibin-B were assessed by immunoassays. In a subset of the girls (n = 91), ovarian volume and the number/size of antral follicles were assessed by TAUS. Genotypes were determined by competitive PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

FSHR c.2039A>G minor alleles were positively associated with serum FSH (β = 0.08, P = 0.004), LH (β = 0.06, P = 0.012) and estradiol (β = 0.06, P = 0.017) (adjusted for Tanner stages). In a combined model, FSHR c.-29G>A and FSHR c.2039A>G alleles were positively associated with FSH levels in early-pubertal girls (B2 + B3, n = 327, r = 0.1, P = 0.02) and in young adolescents (B4 + B5, n = 149, r = 0.2, P = 0.01). Serum AMH and inhibin B levels were not significantly influenced by the single nucleotide polymorphisms (SNPs). Single SNPs were not associated with follicles counts, however, a cumulative minor allele count (FSHB c.-211 G>T and FSHR c.-29G>A) was negatively associated with the number of large follicles (≥5 mm) (n = 91, P = 0.04) (adjusted for Tanner stages).

LIMITATIONS, REASONS FOR CAUTION

Since we studied girls and young adolescents during pubertal transition, our study may not be fully comparable with previous studies on FSHB and FSHR variants in adult women. The group of young adolescents (Tanner B4 + B5) reflects the endocrine situation in adult women best, however, the group is not large enough to contribute substantially to the conflicting results concerning the influence of FSHB c.-211G>T in adult women. Furthermore, we have no information about the exact day of the menstrual cycle in the subgroup of girls with menarche.

WIDER IMPLICATIONS OF THE FINDINGS

The sex-specific interaction of FSHB and FSHR genetic variants and physiological as well as pathological conditions is being increasingly elucidated. The variant triplet set might serve as diagnostic and pharmacogenetic marker. For the first time, we show an additional effect of FSHR c.-29G>A on serum FSH levels in healthy girls. Moreover, morphological data suggest impaired FSH-induced maturation of ovarian follicles in minor allele carriers of FSHB c.-211G>T and FSHR c.-29G>A. This may explain previous findings of delayed pubertal onset in these girls.

STUDY FUNDING/COMPETING INTERESTS

Funding was provided by the Danish Agency for Science, Technology and Innovation (09-067180), Danish Ministry of the Environment, CeHoS (MST-621-00065), Capital Region of Denmark (December 2011), Ministry of Higher Education and Science (DFF-1331-00113) and EDMaRC (Danish Ministry of Health). A.S.B. was funded from December 2015 by ReproUnion (EU Interreg Öresund-Kattegat-Skagerrak). The authors declare no conflict of interest.

Size matters: Associations between the androgen receptor CAG repeat length and the intrafollicular hormone milieu

Granulosa cell (GC) expressed androgen receptors (AR) and intrafollicular androgens are central to fertility. The transactivating domain of the AR contains a polymorphic CAG repeat sequence, which is linked to the transcriptional activity of AR and may influence the GC function. This study aims to evaluate the effects of the AR CAG repeat length on the intrafollicular hormone profiles, and the gene expression profiles of GC from human small antral follicles. In total, 190 small antral follicles (3-11 mm in diameter) were collected from 58 women undergoing ovarian cryopreservation for fertility preservation. The biallelic mean of the CAG repeat lengths were calculated for each woman, and grouped in three groups: Long CAG repeats (23-26 mean CAG); medium CAG repeats (20.5-22.5 mean CAG) and short CAG repeats (17.5-20.0 mean CAG). The following parameters were measured: follicle diameter, intrafollicular levels of Anti-Müllerian Hormone (AMH), progesterone, oestradiol, testosterone and androstenedione, and GC gene expression levels of FSHR, LHR, AR, CYP19A1, and AMH. The long CAG repeat lengths were associated with significantly decreased testosterone levels, as compared to medium CAG repeats (P = 0.05) and short CAG repeats (P = 0.003). Furthermore, in follicles 3-6 mm in diameter, the long CAG repeats were associated with significantly increased LHR and CYP19A1 gene expression levels compared to short CAG repeat lengths (P = 0.004 and P = 0.04 respectively), and significantly increased LHR expression compared to medium CAG repeat lengths (P = 0.03). In conclusion, long CAG repeat lengths in the AR were associated to significant attenuated levels of androgens and an increased conversion of testosterone into oestradiol, in human small antral follicles.

Optimizing outcomes from ovarian tissue cryopreservation and transplantation; activation versus preservation

Ovarian tissue cryopreservation and transplantation (OTCP) is gaining increasing traction in the field of fertility preservation as a result of accumulated successes. We now have a decade of experience with the technique, with tens of live births and greater than 90% return of ovarian function in graft recipients. Recently, a novel method of OTCP has been described, termed in vitro activated OTCP which proposes significant changes to the standard protocol. This method aims to stimulate activation of dormant follicles within the grafts prior to transplantation and ensure that mature oocytes can be generated in the immediate short term after transplantation. By contrast, conventional OTCP seeks to maintain dormancy and thus preserve the follicle reserve in the graft with the aim of maximizing graft lifespan. This opinion paper will compare the two methods of OTCP, highlighting their respective advantages and disadvantages, and provide suggestions as to when to apply either one of these methods in a clinical setting.