CFP1-dependent histone H3K4 trimethylation in murine oocytes facilitates ovarian follicle recruitment and ovulation in a cell-nonautonomous manner.
Sha Qian-Qian,Jiang Yu,Yu Chao,Xiang Yunlong,Dai Xing-Xing,Jiang Jun-Chao,Ou Xiang-Hong,Fan Heng-Yu
Cellular and molecular life sciences : CMLS
CxxC-finger protein 1 (CFP1)-mediated trimethylated histone H3 at lysine-4 (H3K4me3) during oocyte development enables the oocyte genome to establish the competence to generate a new organism. Nevertheless, it remains unclear to which extent this epigenetic modification forms an instructive component of ovarian follicle development. We investigated the ovarian functions using an oocyte-specific Cxxc1 knockout mouse model, in which the H3K4me3 accumulation is downregulated in oocytes of developing follicles. CFP1-dependent H3K4 trimethylation in oocytes was necessary to maintain the expression of key paracrine factors and to facilitate the communication between an oocyte and the surrounding granulosa cells. The distinct gene expression patterns in cumulus cells within preovulatory follicles were disrupted by the Cxxc1 deletion in oocytes. Both follicle growth and ovulation were compromised after CFP1 deletion, because Cxxc1 deletion in oocytes indirectly impaired essential signaling pathways in granulosa cells that mediate the functions of follicle-stimulating hormone and luteinizing hormone. Therefore, CFP1-regulated epigenetic modification of the oocyte genome influences the responses of ovarian follicles to gonadotropin in a cell-nonautonomous manner.
10.1007/s00018-019-03322-y
TMCO1 is essential for ovarian follicle development by regulating ER Ca store of granulosa cells.
Sun Zhongshuai,Zhang Hui,Wang Xi,Wang Qiao-Chu,Zhang Chuanchao,Wang Jiu-Qiang,Wang Yi-Han,An Chao-Qiang,Yang Ke-Yan,Wang Yun,Gao Fei,Guo Caixia,Tang Tie-Shan
Cell death and differentiation
TMCO1 (transmembrane and coiled-coil domains 1) is an endoplasmic reticulum (ER) transmembrane protein that actively prevents Ca stores from overfilling. To characterize its physiological function(s), we generated Tmco1 knockout (KO) mice. In addition to the main clinical features of human cerebrofaciothoracic (CFT) dysplasia spectrum, Tmco1 females manifest gradual loss of ovarian follicles, impaired ovarian follicle development, and subfertility with a phenotype analogous to the premature ovarian failure (POF) in women. In line with the role of TMCO1 as a Ca load-activated Ca channel, we have detected a supernormal Ca signaling in Tmco1 granulosa cells (GCs). Interestingly, although spontaneous Ca oscillation pattern was altered, ER Ca stores of germinal vesicle (GV) stage oocytes and metaphase II (MII) arrested eggs were normal upon Tmco1 ablation. Combined with RNA-sequencing analysis, we also detected increased ER stress-mediated apoptosis and enhanced reactive oxygen species (ROS) level in Tmco1 GCs, indicating the dysfunctions of GCs upon TMCO1 deficiency. Taken together, these results reveal that TMCO1 is essential for ovarian follicle development and female fertility by maintaining ER Ca homeostasis of GCs, disruption of which causes ER stress-mediated apoptosis and increased cellular ROS level in GCs and thus leads to impaired ovarian follicle development.
10.1038/s41418-018-0067-x
Melatonin prevents cisplatin-induced primordial follicle loss via suppression of PTEN/AKT/FOXO3a pathway activation in the mouse ovary.
Jang Hoon,Lee Ok-Hee,Lee Youngeun,Yoon Hyemin,Chang Eun Mi,Park Miseon,Lee Jeong-Woong,Hong Kwonho,Kim Jung Oh,Kim Nam Keun,Ko Jung Jae,Lee Dong Ryul,Yoon Tae Ki,Lee Woo Sik,Choi Youngsok
Journal of pineal research
Premature ovarian failure (POF) is a major side effect of chemotherapy in young cancer patients. To develop pharmaceutical agents for preserving fertility, it is necessary to understand the mechanisms responsible for chemotherapy-induced follicle loss. Here, we show that treatment with cisplatin, a widely used anticancer drug, depleted the dormant follicle pool in mouse ovaries by excessive activation of the primordial follicles, without inducing follicular apoptosis. Moreover, we show that co-treatment with the antioxidant melatonin prevented cisplatin-induced disruption of the follicle reserve. We quantified the various stages of growing follicles, including primordial, primary, secondary, and antral, to demonstrate that cisplatin treatment alone significantly decreased, whereas melatonin co-treatment preserved, the number of primordial follicles in the ovary. Importantly, analysis of the PTEN/AKT/FOXO3a pathway demonstrated that melatonin significantly decreased the cisplatin-mediated inhibitory phosphorylation of PTEN, a key negative regulator of dormant follicle activation. Moreover, melatonin prevented the cisplatin-induced activating phosphorylation of AKT, GSK3β, and FOXO3a, all of which trigger follicle activation. Additionally, we show that melatonin inhibited the cisplatin-induced inhibitory phosphorylation and nuclear export of FOXO3a, which is required in the nucleus to maintain dormancy of the primordial follicles. These findings demonstrate that melatonin attenuates cisplatin-induced follicle loss by preventing the phosphorylation of PTEN/AKT/FOXO3a pathway members; thus, melatonin is a potential therapeutic agent for ovarian protection and fertility preservation during chemotherapy in female cancer patients.
10.1111/jpi.12316
Implications of Nonphysiological Ovarian Primordial Follicle Activation for Fertility Preservation.
Grosbois Johanne,Devos Melody,Demeestere Isabelle
Endocrine reviews
In recent years, ovarian tissue cryopreservation has rapidly developed as a successful method for preserving the fertility of girls and young women with cancer or benign conditions requiring gonadotoxic therapy, and is now becoming widely recognized as an effective alternative to oocyte and embryo freezing when not feasible. Primordial follicles are the most abundant population of follicles in the ovary, and their relatively quiescent metabolism makes them more resistant to cryoinjury. This dormant pool represents a key target for fertility preservation strategies as a resource for generating high-quality oocytes. However, development of mature, competent oocytes derived from primordial follicles is challenging, particularly in larger mammals. One of the main barriers is the substantial knowledge gap regarding the regulation of the balance between dormancy and activation of primordial follicles to initiate their growing phase. In addition, experimental and clinical factors also affect dormant follicle demise, while the mechanisms involved remain largely to be elucidated. Moreover, most of our basic knowledge of these processes comes from rodent studies and should be extrapolated to humans with caution, considering the differences between species in the reproductive field. Overcoming these obstacles is essential to improving both the quantity and the quality of mature oocytes available for further fertilization, and may have valuable biological and clinical applications, especially in fertility preservation procedures. This review provides an update on current knowledge of mammalian primordial follicle activation under both physiological and nonphysiological conditions, and discusses implications for fertility preservation and priorities for future research.
10.1210/endrev/bnaa020
Synergistic effect of melatonin and ghrelin in preventing cisplatin-induced ovarian damage via regulation of FOXO3a phosphorylation and binding to the p27 promoter in primordial follicles.
Jang Hoon,Na Younghwa,Hong Kwonho,Lee Sangho,Moon Sohyeon,Cho Minha,Park Miseon,Lee Ok-Hee,Chang Eun Mi,Lee Dong Ryul,Ko Jung Jae,Lee Woo Sik,Choi Youngsok
Journal of pineal research
Premature ovarian failure during chemotherapy is a serious problem for young women with cancer. To preserve the fertility of these patients, approaches to prevent chemotherapy-induced ovarian failure are needed. In a previous study, we reported that melatonin treatment prevents the depletion of the dormant follicle pool via repression of the simultaneous activation of dormant primordial follicles by cisplatin. However, melatonin's protective effect was only partial and thus insufficient. In this study, we found that the hormone ghrelin enhances the protective effect of melatonin against cisplatin-induced ovarian failure in mouse model. Co-administration of melatonin and ghrelin more effectively prevented cisplatin-induced follicle disruption. Simultaneous treatment with melatonin and ghrelin almost restored the number of primordial follicles and the corpus luteum in cisplatin-treated ovaries, compared with single administration. We found melatonin and ghrelin receptors on the cell membrane of premature oocytes of primordial follicles. In addition, melatonin and ghrelin co-administration inhibited the cisplatin-induced phosphorylation of PTEN and FOXO3a that induces cytoplasmic translocation of FOXO3a. Inhibition of FOXO3a phosphorylation by melatonin and ghrelin increased the binding affinity of FOXO3a for the p27 promoter in primordial follicles. Co-administration of melatonin and ghrelin in cisplatin-treated ovaries restored the expression of p27 , which is critical for retention of the dormant status of primordial follicles. In conclusion, these findings suggest that melatonin and ghrelin co-administration is suitable for use as a fertoprotective adjuvant therapy during cisplatin chemotherapy in young female cancer patients.
10.1111/jpi.12432
Cellular and molecular regulation of the activation of mammalian primordial follicles: somatic cells initiate follicle activation in adulthood.
Zhang Hua,Liu Kui
Human reproduction update
BACKGROUND:The first small follicles to appear in the mammalian ovaries are primordial follicles. The initial pool of primordial follicles serves as the source of developing follicles and oocytes for the entire reproductive lifespan of the animal. Although the selective activation of primordial follicles is critical for female fertility, its underlying mechanisms have remained poorly understood. METHODS:A search of PubMed was conducted to identify peer-reviewed literature pertinent to the study of mammalian primordial follicle activation, especially recent reports of the role of primordial follicle granulosa cells (pfGCs) in regulating this process. RESULTS:In recent years, molecular mechanisms that regulate the activation of primordial follicles have been elucidated, mostly through the use of genetically modified mouse models. Several molecules and pathways operating in both the somatic pfGCs and oocytes, such as the phosphatidylinositol 3 kinase (PI3K) and the mechanistic target of rapamycin complex 1 (mTORC1) pathways, have been shown to be important for primordial follicle activation. More importantly, recent studies have provided an updated view of how exactly signaling pathways in pfGCs and in oocytes, such as the KIT ligand (KL) and KIT, coordinate in adult ovaries so that the activation of primordial follicles is achieved. CONCLUSIONS:In this review, we have provided an updated picture of how mammalian primordial follicles are activated. The functional roles of pfGCs in governing the activation of primordial follicles in adulthood are highlighted. The in-depth understanding of the cellular and molecular mechanisms of primordial follicle activation will hopefully lead to more treatments of female infertility, and the current progress indicates that the use of existing primordial follicles as a source for obtaining fertilizable oocytes as a new treatment for female infertility is just around the corner.
10.1093/humupd/dmv037
Hippo pathway functions as a downstream effector of AKT signaling to regulate the activation of primordial follicles in mice.
Hu Liao-Liao,Su Tie,Luo Rui-Chen,Zheng Yue-Hui,Huang Jian,Zhong Zhi-Sheng,Nie Jing,Zheng Li-Ping
Journal of cellular physiology
Clarifying the molecular mechanisms by which primordial follicles are initiated is crucial for the prevention and treatment of female infertility and ovarian dysfunction. The Hippo pathway has been proven to have a spatiotemporal correlation with the size of the primordial follicle pool in mice in our previous work. But the role and underlying mechanisms of the Hippo pathway in primordial follicle activation remain unclear. Here, the localization and expression of the core components were examined in primordial follicles before and after activation. And the effects of the Hippo pathway on primordial follicle activation were determined by genetically manipulating yes-associated protein 1 (Yap1), the key transcriptional effector. Furthermore, an AKT specific inhibitor (MK2206) was added to determine the interaction between the Hippo pathway and AKT, an important signaling regulator of ovarian function. Results showed that the core components of the Hippo pathway were localized in both primordial and primary follicles and the expression levels of them changed significantly during the initiation of primordial follicles. Yap1 knockdown suppressed primordial follicle activation, while its overexpression led to the opposite trend. MK2206 downregulated the ratio of P-MST/MST1 and upregulated the ratio of P-YAP1/YAP1 significantly, whereas Yap1-treatment had no influence on AKT. In addition, YAP1 upregulation partially rescued the suppression of the primordial follicle activation induced by MK2206. Our findings revealed that the Hippo-YAP1 regulates primordial follicular activation, which is mediated by AKT signaling in mice, thus providing direct and new evidence to highlight the role of Hippo signaling in regulating ovarian follicles development.
10.1002/jcp.27024
Dormancy and activation of human oocytes from primordial and primary follicles: molecular clues to oocyte regulation.
Human reproduction (Oxford, England)
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.
10.1093/humrep/dex238
The Factors and Pathways Regulating the Activation of Mammalian Primordial Follicles .
Chen Yao,Yang Weina,Shi Xu,Zhang Chenlu,Song Ge,Huang Donghui
Frontiers in cell and developmental biology
Mammalian ovaries consist of follicles as basic functional units. Each follicle comprised an innermost oocyte and several surrounding flattened granulosa cells. Unlike males, according to the initial size of the primordial follicle pool and the rate of its activation and depletion, a female's reproductive life has been determined early in life. Primordial follicles, once activated, will get into an irreversible process of development. Most follicles undergo atretic degeneration, and only a few of them could mature and ovulate. Although there are a lot of researches contributing to exploring the activation of primordial follicles, little is known about its underlying mechanisms. Thus, in this review, we collected the latest papers and summarized the signaling pathways as well as some factors involved in the activation of primordial follicles, hoping to lead to a more profound understanding of the cellular and molecular mechanisms of primordial follicle activation.
10.3389/fcell.2020.575706
Granulosa cells from human primordial and primary follicles show differential global gene expression profiles.
Ernst E H,Franks S,Hardy K,Villesen P,Lykke-Hartmann K
Human reproduction (Oxford, England)
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.
10.1093/humrep/dey011
Transcripts Encoding the Androgen Receptor and IGF-Related Molecules Are Differently Expressed in Human Granulosa Cells From Primordial and Primary Follicles.
Steffensen Line L,Ernst Emil H,Amoushahi Mahboobeh,Ernst Erik,Lykke-Hartmann Karin
Frontiers in cell and developmental biology
Bidirectional cross talk between granulosa cells and oocytes is known to be important in all stages of mammalian follicular development. Insulin-like growth factor (IGF) signaling is a prominent candidate to be involved in the activation of primordial follicles, and may be be connected to androgen-signaling. In this study, we interrogated transcriptome dynamics in granulosa cells isolated from human primordial and primary follicles to reveal information of growth factors and androgens involved in the physiology of ovarian follicular activation. Toward this, a transcriptome comparison study on primordial follicles ( = 539 follicles) and primary follicles ( = 261 follicles) donated by three women having ovarian tissue cryopreserved before chemotherapy was performed. The granulosa cell contribution in whole follicle isolates was extracted . Modeling of complex biological systems was performed using IPA® software. We found the granulosa cell compartment of the human primordial and primary follicles to be extensively enriched in genes encoding IGF-related factors, and the Androgen Receptor (AR) enriched in granulosa cells of primordial follicles. Our study hints the possibility that primordial follicles may indeed be androgen responsive, and that the action of androgens represents a connection to the expression of key players in the IGF-signaling pathway including IGF1R, IGF2, and IGFBP3, and that this interaction could be important for early follicular activation. In line with this, several androgen-responsive genes were noted to be expressed in both oocytes and granulosa cells from human primordial and primary follicle. We present a detailed description of and gene activities in the human granulosa cell compartment of primordial and primary follicles, suggesting that these cells may be or prepare to be responsive toward androgens and IGFs.
10.3389/fcell.2018.00085
ELAVL2-directed RNA regulatory network drives the formation of quiescent primordial follicles.
Kato Yuzuru,Iwamori Tokuko,Ninomiya Youichirou,Kohda Takashi,Miyashita Jyunko,Sato Mikiko,Saga Yumiko
EMBO reports
Formation of primordial follicles is a fundamental, early process in mammalian oogenesis. However, little is known about the underlying mechanisms. We herein report that the RNA-binding proteins ELAVL2 and DDX6 are indispensable for the formation of quiescent primordial follicles in mouse ovaries. We show that Elavl2 knockout females are infertile due to defective primordial follicle formation. ELAVL2 associates with mRNAs encoding components of P-bodies (cytoplasmic RNP granules involved in the decay and storage of RNA) and directs the assembly of P-body-like granules by promoting the translation of DDX6 in oocytes prior to the formation of primordial follicles. Deletion of Ddx6 disturbs the assembly of P-body-like granules and severely impairs the formation of primordial follicles, indicating the potential importance of P-body-like granules in the formation of primordial follicles. Furthermore, Ddx6-deficient oocytes are abnormally enlarged due to misregulated PI3K-AKT signaling. Our data reveal that an ELAVL2-directed post-transcriptional network is essential for the formation of quiescent primordial follicles.
10.15252/embr.201948251
Distinct expression patterns of TLR transcripts in human oocytes and granulosa cells from primordial and primary follicles.
Ernst E H,Amoushahi M,Sørensen A S,Kragstrup T W,Ernst E,Lykke-Hartmann K
Journal of reproductive immunology
Ovulation has long been regarded as a process resembling an inflammatory response. Previously, luteinizing hormone (LH) was shown to induce Toll-like receptor 2 (TLR2) and TLR4 in granulosa cells from preovulatory hormone-dependent follicles. However, whether this could already initiate before the hormone-dependent phase is currently unknown. The aim of this study was to investigate TLR genes in human oocytes and granulosa cells from primordial and primary ovarian follicles during the hormone-independent phase. A class-comparison study of existing oocyte and granulosa cell RNA sequencing transcriptomes from primordial (n = 539 follicles) and primary (n = 261) follicles collected from three patients was examined. This revealed a distinct expression pattern of TLR3, TLR4 and TLR5 transcripts. Interestingly, the TLR3 protein was differentially detected in both the oocyte and the granulosa cells in primordial and primary follicles, suggesting that TLR3 is maternally contributed both as mRNA and protein. Intracellularly, the compartmentalized TLR3 dot-like staining in the intersection between the oocyte and the surrounding primordial granulosa cells. The TLR4 protein was detected in both primordial and primary follicles, with a notable staining in the granulosa cells. We functionally challenged ovaries in vitro, by polyinosinic:polycytidylic acid (poly I:C) and LPS, known to activate TLR3 and TLR4, respectively, and found a tendency for increased IL-6 production, which was particular evident in the LPS-treated group. Based on the expression of TLRs, it is notably that human primordial and primary follicles express genes that would allow them to respond to innate immune proteins and cytokines during follicle activation.
10.1016/j.jri.2020.103125