Lipid droplet formation is spatiotemporally regulated in oocytes during follicular development in mice.

Communication between oocytes and the surrounding granulosa cells during follicular development is essential for complete oocyte growth. Oocytes contain lipid droplets (LDs), organelles assembled in the endoplasmic reticulum (ER) that store neutral lipids, including triglycerides and cholesterol esters. Although the LD content varies among animals, LDs stored in oocytes have been shown to play an important role in oocyte maturation and preimplantation embryonic development. However, knowledge is lacking regarding how and when LDs are initially produced in developing oocytes within follicles. In the present study, we found that LDs appeared in mouse oocytes in a specific phase during follicular development. The emergence of LDs in intrafollicular oocytes was induced within a similar time window in vitro and in vivo. Fluorescence imaging and electron microscopy revealed that LDs emerging in oocytes during the early stages of follicular growth were in close proximity to the ER. Furthermore, fatty-acid-tracking experiments have revealed that exogenous fatty acids are rapidly incorporated into oocytes, and their uptake is regulated by the interaction between oocytes and granulosa cells, likely in part through transzonal projections. In summary, our results suggest that LD synthesis observed in growing oocytes is spatiotemporally regulated and that oocyte-granulosa cell contact may be involved in LD biosynthesis during follicular development.

Knockdown of DNMT1 Induces SLCO3A1 to Promote Follicular Growth by Enhancing the Proliferation of Granulosa Cells in Mammals.

In female mammals, the proliferation and apoptosis of granulosa cells (GCs) have been shown to determine the fate of follicles. DNA methyltransferases (DNMTs) and SLCO3A1 have been reported to be involved in the survival of GCs and follicular growth. However, the molecular mechanisms enabling DNMTs to regulate the expression of SLCO3A1 to participate in follicular growth are unclear. In this study, we found that the knockdown of DNMT1 enhanced the mRNA and protein levels of SLCO3A1 by regulating the chromatin accessibility probably. Moreover, SLCO3A1 upregulated the mRNA and protein levels of MCL1, PCNA, and STAR to promote the proliferation of GCs and facilitated cell cycle progression by increasing the mRNA and protein levels of CCNE1, CDK2, and CCND1, but it decreased apoptosis by downregulating the mRNA and protein levels of CASP3 and CASP8. Moreover, SLCO3A1 promoted the growth of porcine follicles and development of mice follicles. In conclusion, the knockdown of DNMT1 upregulated the mRNA and protein levels of SLCO3A1, thereby promoting the proliferation of GCs to facilitate the growth and development of ovarian follicles, and these results provide new insights into investigations of female reproductive diseases.

In Vitro Growth of Human Follicles: Current and Future Perspectives.

Ovarian tissue cryopreservation is gaining importance as a successful method to restore fertility to girls and young women at high risk of sterility. However, there are concerns regarding the safety of transplantation after ovarian tissue cryopreservation due to the high risk of reintroducing cancer cells and causing disease recurrence. In these cases, the development of culture systems that support oocyte development from the primordial follicle stage is required. Notable achievements have been reached in human follicle in vitro growth in the past decade. Currently, systems for the in vitro culture of ovarian tissue are based on two-dimensional substrates that do not support the survival of follicles or recapitulate the mechanical heterogenicity in the mammalian ovary. Recognition of the importance of special arrangements between cells has spurred research in three-dimensional culture systems, and the provision of a precise culture system that maximizes the diffusion of nutrients and gases through the follicles has raised interest in advanced biomimetic models. The current review critically examines various culture systems employed for the in vitro development of follicles, with a particular focus on solutions utilizing Organ-on-a-Chip (OOC) technology. The emphasis on OOC technology underscores its role as a promising avenue in ensuring the successful cultivation and maintenance of follicular structures during the culture period.

Lipid droplet synthesis is associated with angiogenesis in mouse ovarian follicles†.

Lipid droplets (LDs) are endoplasmic reticulum (ER)-derived organelles comprising a core of neutral lipids surrounded by a phospholipid monolayer. Lipid droplets play important roles in lipid metabolism and energy homeostasis. Mammalian ovaries have been hypothesized to use neutral lipids stored in LDs to produce the hormones and nutrients necessary for rapid follicular development; however, our understanding of LD synthesis remains incomplete. In this study, we generated transgenic reporter mice that express mCherry fused to HPos, a minimal peptide that localizes specifically to nascent LDs synthesized at the ER. With this tool for visualizing initial LD synthesis in ovaries, we found that LDs are synthesized continuously in theca cells but rarely in inner granulosa cells (Gc) during early follicular development. Administration of exogenous gonadotropin enhances LD synthesis in the Gc, suggesting that LD synthesis is hormonally regulated. In contrast, we observed copious LD synthesis in the corpus luteum, and excessive LDs accumulation in atretic follicles. Furthermore, we demonstrated that LD synthesis is synchronized with angiogenesis around the follicle and that suppressing angiogenesis caused defective LD biosynthesis in developing follicles. Overall, our study is the first to demonstrate a spatiotemporally regulated interplay between LD synthesis and neovascularization during mammalian follicular development.

Multifaceted Functions of TWSG1: From Embryogenesis to Cancer Development.

Bone morphogenetic proteins (BMPs) play an important role in development. Twisted gastrulation BMP signaling modulator 1 (TWSG1) was initially identified as a regulator of the dorsoventral axis formation in Drosophila. The mechanism of BMP signaling modulation by TWSG1 is complex. TWSG1 inhibits BMP signaling by binding to BMP ligands including BMP4, whereas it enhances signaling by interacting with Chordin, a BMP antagonist. Therefore, TWSG1 can act as both a BMP agonist and antagonist. TWSG1 has various functions ranging from embryogenesis to cancer progression. TWSG1 knockout mice showed neural, craniofacial, and mammary defects. TWSG1 also regulated erythropoiesis and thymocyte development. Furthermore, the relationship between TWSG1 and cancer has been elucidated. Allelic loss of TWSG1 was detected in colorectal cancer. TWSG1 expression was upregulated in papillary thyroid carcinoma and glioblastoma but downregulated in gastric and endometrial cancers. TWSG1 suppressed BMP7-enhanced sphere formation and migration in endometrial cancer cells, indicating its tumor-suppressive role. Further studies are required to clarify the TWSG1 function and its association with BMP signaling in cancer development. Finally, TWSG1 is abundantly expressed in human and mouse ovaries and sustains follicular growth in rodent ovaries. Thus, TWSG1 has various functions ranging from fertility to cancer. Therefore, TWSG1 signaling modulation may be beneficial in treating specific diseases such as cancer.

Accumulation of fibrosis and altered perifollicular stromal differentiation in vitrified-thawed human ovarian tissue xenografted to nude mice.

Purpose: Ovarian tissue cryopreservation and its auto-transplantation is promising technique in fertility preservation. Longevity of grafted tissue is limited though mechanism of follicle reduction is not fully understood. We evaluated histological alteration of vitrified-thawed ovarian tissue that grafted to nude mice. Materials and Methods: Human ovarian tissue was cryopreserved by vitrification. After thawing, they were grafted to mesentery of nude mice. Twelve weeks after transplantation, the implants were removed and histologically examined. The presence of follicles, the degree of fibrosis, and TUNEL staining in surrounding cortex were evaluated. The stromal expressions of alpha-smooth muscle actin (aSMA) were determined. Results: Normal ovarian cortex was decreased, and fibrotic area were significantly increased after grafting. The distributions of developmental stage of follicles shifted toward activation of follicular growth. Stromal TUNEL staining was increased in frozen/thawed tissue. The expression of aSMA were found in perifollicular stroma of growing follicles, which were decreased in grafted tissue associated with reduction of cortical stroma. Conclusions: Fibrosis, reduced cortical stroma, and activation of dormant follicles were concomitantly observed in grafted ovarian cortex, which may relate to limited longevity. Perifollicular aSMA expression can be regarded as a marker of the competence of cortical stroma that regulate follicular development.

Effect of unplanned spontaneous follicular growth and ovulation on pregnancy outcomes in planned artificial frozen embryo transfer cycles: a propensity score matching study.

STUDY QUESTION: Does unplanned spontaneous follicular growth and ovulation affect clinical outcomes after planned artificial frozen-thawed embryo transfer (AC-FET) cycles? SUMMARY ANSWER: AC-FET and spontaneous follicular growth and ovulation events resulted in notably better pregnancy outcomes with a significantly higher implantation rate (IR), clinical pregnancy rate (CPR), ongoing pregnancy rate (OPR) and live birth rate (LBR) and a significantly lower miscarriage rate. WHAT IS KNOWN ALREADY: The AC-FET protocol without GnRH agonist administration is associated with a low incidence of follicular growth and ovulation. In the literature, authors often refer to these types of cycles with concern due to possibly impaired FET outcomes. However, the real impact of such cycles has yet to be elucidated due to the lack of existing data. STUDY DESIGN, SIZE, DURATION: This was a retrospective clinical study involving 2256 AC-FET cycles conducted between January 2017 and August 2019. Propensity score (PS) matching was used to control for confounding variables. PARTICIPANTS/MATERIALS, SETTING, METHODS: Subjects were divided into two groups: a study group: cycles with spontaneous follicular growth and ovulation (the maximum diameter of follicles in any ovary was ≥14 mm and ovulation was confirmed by consecutive ultrasound examinations) and a control group featuring cycles without growing follicles (the maximum diameter of follicles in both ovaries were <10 mm). The study group was matched by PS with the control group at a ratio of 1:2. The study group consisted of 195 patients before PS matching and 176 patients after matching. The numbers of participants in the control group before and after PS matching were 2061 and 329, respectively. MAIN RESULTS AND THE ROLE OF CHANCE: This analysis showed that patient age (adjusted odds ratio [aOR] 1.05; 95% CI 1.01-1.09; P=0.010) and basal FSH level (aOR 1.06; 95% CI 1.01-1.11; P=0.012) were significantly and positively related with the spontaneous follicular growth and ovulation event. In addition, this event was negatively correlated with BMI (aOR 0.92; 95% CI 0.87-0.97; P=0.002), AMH level (aOR 0.66; 95% CI 0.59-0.74; P<0.001) and a high starting oestrogen dose (aOR 0.53; 95% CI 0.38-0.76 for 6 mg vs. 4 mg; P<0.001). Baseline characteristics were similar between groups after PS matching. Patients in the study group had a significantly higher IR (28.8% vs. 21.8%, P=0.016), CPR (44.9% vs. 33.4%, P=0.011), OPR (39.2% vs. 26.1%, P=0.002) and LBR (39.2% vs. 24.9%, P=0.001) and a lower miscarriage rate (12.7% vs. 25.5%, P=0.030), compared with those in the control group. LIMITATIONS, REASONS FOR CAUTION: This was a retrospective study carried out in a single centre and was therefore susceptible to bias. In addition, we only analysed patients with normal ovulation patterns and excluded those with follicular growth but without ovulation. Further studies remain necessary to confirm our results. WIDER IMPLICATIONS OF THE FINDINGS: It is not necessary to cancel cycles that experience spontaneous follicular growth and ovulation. Our data support promising clinical outcomes after this event. Our findings are important as they can better inform clinicians and patients. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by National Natural Science Foundation of China (grant no. 81701507, 81801404, 81871210, 82071648), Natural Science Foundation of Jiangsu Province (grant no. BK20171126, BK20201123) and Jiangsu Province '333' project. The authors declare that they have no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Stem cell-secreted factor therapy regenerates the ovarian niche and rescues follicles.

BACKGROUND: Ovarian senescence is a normal age-associated phenomenon, but increasingly younger women are affected by diminished ovarian reserves or premature ovarian insufficiency. There is an urgent need for developing therapies to improve ovarian function in these patients. In this context, previous studies suggest that stem cell-secreted factors could have regenerative properties in the ovaries. OBJECTIVE: This study aimed to test the ability of various human plasma sources, enriched in stem cell-secreted factors, and the mechanisms behind their regenerative properties, to repair ovarian damage and to promote follicular development. STUDY DESIGN: In the first phase, the effects of human plasma enriched in bone marrow stem cell soluble factors by granulocyte colony-stimulating factor mobilization, umbilical cord blood plasma, and their activated forms on ovarian niche, follicle development, and breeding performance were assessed in mouse models of chemotherapy-induced ovarian damage (n=7 per group). In addition, the proteomic profile of each plasma was analyzed to find putative proteins and mechanism involved in their regenerative properties in ovarian tissue. In the second phase, the most effective plasma treatment was validated in human ovarian cortex xenografted in immunodeficient mice (n=4 per group). RESULTS: Infusion of human plasma enriched bone marrow stem cell soluble factors by granulocyte colony-stimulating factor mobilization or of umbilical cord blood plasma-induced varying degrees of microvessel formation and cell proliferation and reduced apoptosis in ovarian tissue to rescue follicular development and fertility in mouse models of ovarian damage. Plasma activation enhanced these effects. Activated granulocyte colony-stimulating factor plasma was the most potent inducing ovarian rescue in both mice and human ovaries, and proteomic analysis indicated that its effects may be mediated by soluble factors related to cell cycle and apoptosis, gene expression, signal transduction, cell communication, response to stress, and DNA repair of double-strand breaks, the most common form of age-induced damage in oocytes. CONCLUSION: Our findings suggested that stem cell-secreted factors present in both granulocyte colony-stimulating factor-mobilized and umbilical cord blood plasma could be an effective treatment for increasing the reproductive outcomes in women with impaired ovarian function owing to several causes. The activated granulocyte colony-stimulating factor plasma, which is already enriched in both stem cell-secreted factors and platelet-enclosed growth factors, seems to be the most promising treatment because of its most potent restorative effects on the ovary together with the autologous source.

Significance of pro-angiogenic estrogen metabolites in normal follicular development and follicular growth arrest in polycystic ovary syndrome.

STUDY QUESTION: Do alterations in pro- and anti-angiogenic estrogen metabolites in follicular fluid (FF) contribute to the follicular growth arrest and anovulation associated with polycystic ovary syndrome (PCOS)? SUMMARY ANSWER: FF of PCOS women with anovulation have reduced levels of pro-angiogenic estrogen metabolites (EMs) and vascular endothelial growth factor (VEGF) compared to that of fertile women with regular menstrual cycles, but exogenous gonadotropins increase the pro-angiogenic EMs and VEGF levels in PCOS women. WHAT IS KNOWN ALREADY: PCOS is characterized by the arrest of follicular development that leads to chronic anovulation. Follicular arrest is generally associated with elevated plasma levels of luteinizing hormone (LH), androgens and anti-Mullerian hormone (AMH). There is also reduced angiogenesis in the follicles of PCOS women compared to those of normal cycling women. It is known that angiogenesis is a critical factor during follicular development. We and other investigators have explored the role of EMs in ovarian angiogenesis, particularly in human corpus luteum function, showing that 4-hydroxyestrone (4-OHE1) and 16-ketoestradiol (16-kE2) have pro-angiogenic effects while 2-methoxyestradiol (2-ME2) and 2-methoxyestrone (2-ME1) have anti-angiogenic effects. Additionally, 2-hydroxyestradiol (2-OHE2), which is produced in the ovary, has proliferative and pro-angiogenic properties. We hypothesized that EMs could be involved in angiogenesis necessary for ovarian follicular development in fertile women, and that dysregulation of these factors may contribute to follicular arrest in PCOS. The relationship between EMs, VEGF and AMH in the pathophysiology of follicular arrest in PCOS has not been previously studied at a follicular level in anovulatory women without ovulation induction. STUDY DESIGN, SIZE, DURATION: This is a comparative experimental study of serum and FF collected from different sized follicles (antral ˂10 mm and dominant ˃16 mm) of women with and without ovarian stimulation. The study included women with regular menstrual cycles who were proven to be fertile (n = 20) and PCOS women with follicular arrest who were candidates for ovarian drilling (n = 17), as well as other patients requiring ovarian stimulation, i.e. control women undergoing IVF for male factor infertility (n = 12) and PCOS women undergoing IVF (n = 17). In vitro studies were carried out on granulosa-lutein cells (GCs) obtained from subsets of women undergoing IVF for male factor infertility (n = 6) and PCOS women undergoing IVF (n = 6). GCs were maintained in culture for up to 6 days. PARTICIPANTS/MATERIALS, SETTING, METHODS: Intrafollicular estradiol, estrone and EMs concentrations were determined by high performance liquid chromatography-mass spectrometry. Testosterone in serum was measured by RIA, and LH, FSH and sex hormone-binding globulin in serum were measured with IRMA kits. AMH was determined in serum and FF by enzyme linked immunosorbant assay (ELISA). VEGF levels were measured in FF and conditioned medium by ELISA. Conditioned medium were obtained from cultured GCs. The angiogenic potential was assessed by in vitro angiogenic assays. MAIN RESULTS AND THE ROLE OF CHANCE: Pro-angiogenic EMs (4-OHE1, 16-kE2 and 2-OHE2) and VEGF were lower in FF of antral follicles of PCOS women with follicular arrest compared those of fertile women with ovulatory cycles (P < 0.05). In contrast, higher concentrations of AMH were found in FF of antral follicles from PCOS women with follicular arrest compared to those of fertile women with ovulatory cycles (P < 0.05). Exogenous gonadotropins used in IVF increased pro-angiogenic EMs and VEGF production in PCOS women, reaching similar profiles compared to control women receiving gonadotropins in their IVF treatment for male factor infertility. The pro-angiogenic EM 2-OHE2 increased the angiogenic potential and VEGF levels of GCs from PCOS women compared to the basal condition (P < 0.05). These findings suggest that there is a role for pro-angiogenic EMs in the control of follicular VEGF production. LIMITATIONS, REASONS FOR CAUTION: The limitations include the possibility that in vitro analysis of GCs might not reflect the in vivo mechanisms involved in the pro-angiogenic action of 2-OHE2 since GCs obtained at the time of oocyte retrieval belong to a very early stage of the luteal phase and might not be representative of GCs during follicular growth. Therefore, our findings do not conclusively rule out the possibility that other in vivo mechanisms also account for defective angiogenesis observed in PCOS. WIDER IMPLICATIONS OF THE FINDINGS: The present study highlights the significance of EMs, angiogenic factors and AMH and their interaction in the pathophysiology of follicular development in PCOS. This study provides new insights into the role of pro-angiogenic factors in follicular arrest in PCOS. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by CONICYT/FONDECYT 1140693 and NIH grant R01HD083323. All authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.

The localization and expression of epidermal growth factor and epidermal growth factor receptor in bovine ovary during oestrous cycle.

Epidermal growth factor (EGF) is one of the important regulatory factors of EGF family. EGF has been indicated to effectively inhibit the apoptosis of follicular cells, to promote the proliferation of granulosa cells and the maturation of oocytes, and to induce ovulation process via binding to epidermal growth factor receptor (EGFR). However, little is known about the distribution and expression of EGF and EGFR in cattle ovary especially during oestrous cycle. In this study, the localization and expression rule of EGF and EGFR in cattle ovaries of follicular phase and luteal phase at different time points in oestrous cycle were investigated by using IHC and real-time qPCR. The results showed that EGF and EGFR in cattle ovary were mainly expressed in granulosa cells, cumulus cells, oocytes, zona pellucida, follicular fluid and theca folliculi externa of follicles. The protein and mRNA expression of EGF/EGFR in follicles changed regularly with the follicular growth wave both in follicular and in luteal phase ovaries. In follicular phase ovaries, the protein expression of EGF and EGFR was higher in antral follicles than that of those in other follicles during follicular growth stage, and the mRNA expression of EGFR was also increased in stage of dominant follicle selection. However, in luteal phase ovaries, the growth of follicles was impeded during corpus luteum development under the action of progesterone secreted by granular lutein cell. The mRNA and protein expressions of EGF and EGFR in ovarian follicles during oestrous cycle indicate that they play a role in promoting follicular development in follicular growth waves and mediating the selection process of dominant follicles.

Stimulation of nicotinic receptors in the suprachiasmatic nucleus results in a higher number of growing follicles and ova shed.

NEW FINDINGS: What is the central question of this study? What is the role of the nicotinic system of the suprachiasmatic nucleus (SCN) in the regulation of follicular growth and ovulation? What is the main finding and its importance? The stimulation of the nicotinic system of the pro-oestrus rat SCN results in an increase in the number of ova shed, in the number of growing ovarian follicles and in the secretion of oestradiol. ABSTRACT: The timing of the preovulatory luteinizing hormone surge that leads to ovulation depends to a large extent on a functional circadian clock that is localized in the suprachiasmatic nucleus (SCN). The activities of the SCN are regulated by several neurotransmitter systems, including the muscarinic system. Given that acetylcholine binds to muscarinic (mAChRs) and nicotinic (nAChRs) receptors, in the present study, we analysed the effects of unilaterally stimulating nAChRs in the left or right SCN. Stimulation treatment was administered in rats in pro-oestrus at 09.00 or 19.00 h by injecting 0.3 µl of a nicotine solution (200 µm). The effects of the stimulation were assessed by evaluating the number of ova shed, the number of ovarian follicles, and the levels of oestradiol and progesterone in serum 24 h after treatment. We observed that regardless of the time (4 h after lights on, 09.00 h, or immediately after lights off, 19.00 h) or the side of the SCN treated, the unilateral microinjection of nicotine resulted in a higher number of ova shed and higher number of growing follicles in the ovaries as well as higher oestradiol serum levels. When the nicotine microinjection treatment failed to reach the SCN, the oestradiol levels in serum were similar to those of animals treated with vehicle solution. Based on the current results, we suggest that during pro-oestrus, the nicotinic neuronal information in the SCN modulates follicular growth and ovulation in a stimulatory manner.

Usefulness of intermittent clomiphene citrate treatment for women with polycystic ovarian syndrome that is resistant to standard clomiphene citrate treatment.

PURPOSE: Clomiphene citrate (CC) has been used as a first-line treatment for anovulatory polycystic ovary syndrome (PCOS). However, some patients with PCOS are resistant to standard CC treatment. In this study, a new CC treatment protocol was developed, named "intermittent CC treatment" (ICT) and its efficacy was investigated on the induction of follicular growth in patients with PCOS who were resistant to standard CC treatment. METHODS: Of the 42 patients with PCOS who were resistant to standard CC treatment (50 mg/day, 5 days), 26 underwent ICT. They were given 100 mg/day of CC for 5 days from the next menstrual cycle day (MCD) 5 (first CC). If follicular growth was not observed on MCD 14, they were given 100 mg/day of CC for 5 days (MCD 14-MCD 18) (second CC). If follicular growth still was not observed on MCD 23, they were treated with CC again in the same way (third CC). RESULTS: The first CC, second CC, and third CC were effective for 3/26 (11.5%) patients, 12/23 (52.2%) patients, and 6/11 (54.5%) patients, respectively. In total, ICT was effective for 21/26 (80.8%) patients with CC-resistant PCOS. CONCLUSION: Thus, ICT is a useful treatment and could be an alternative to gonadotropin therapy for patients with CC-resistant PCOS.

Analysis of the Effect of Leukemia Inhibitory Factor on Follicular Growth in Cultured Murine Ovarian Tissue.

Leukemia inhibitory factor (LIF) is expressed in the ovary and controls follicular growth. LIF has been reported to accelerate the primordial to primary follicle transition, the growth of cultured preantral follicles, and the maturation of oocytes. Previous reports on factors that regulate follicular growth have largely employed cultured follicles. However, there are several types of follicles and somatic cells in the ovary that are likely to interact with one another to regulate follicular growth. Therefore, a novel approach is essential for understanding the function of factors that regulate follicular growth in the ovary. In this study, we evaluated the function of LIF using cultured ovarian tissue. Ovarian tissue slices were cultured in the presence or absence of recombinant LIF and neutralizing anti-LIF antibody to enable continuous monitoring of follicular growth within the context of the ovary as well as analysis of the process of follicular growth. The results revealed that LIF inhibited the growth of primary, secondary, and antral follicles. Furthermore, we verified the inhibitory function of LIF using the neutralizing antibody, which accelerated follicular growth. These results suggest that LIF is likely to coordinate follicular growth in the ovary. The culture and analysis methods employed in this study are thus effective for clarifying the tissue-level functions of factors that regulate follicular growth within the ovary.

Evidence of the activation of unfolded protein response in granulosa and cumulus cells during follicular growth and maturation.

The objective of the present study is to investigate whether unfolded protein response (UPR), activated by endoplasmic reticulum (ER) stress, in granulosa cells (GC) and cumulus cells (CC) is involved in the process of follicular growth and maturation. First, to examine the presence of UPR in growing follicles, the expression of spliced form of X-box-binding protein 1 (XBP1(S)) and heat shock 70 kDa protein 5 (HSPA5) mRNA, typical UPR genes, in mice ovaries were examined by in situ hybridization. GC of later stage than large secondary follicles expressed both XBP1(S) and HSPA5 mRNA, which was accompanied with the activation of ER stress sensor proteins, inositol-requiring enzyme 1 (IRE1) and double-stranded RNA-activated protein kinase-like ER kinase (PERK), confirmed by immunohistochemistry. Next, to examine the association between the fertilization capacity of oocytes and the expression levels of UPR genes in surrounding CC, human CC were collected from patients undergoing ICSI. The expression levels of XBP1(S) mRNA, quantified by RT-PCR, in CC enclosing human oocytes achieving fertilization were two-fold higher, than those in CC enclosing oocytes without fertilization capacity. In conclusion, UPR is activated during follicular growth and suggested to be involved in the process of follicular growth and maturation.

Preovulatory follicle diameter, growth rate and time of ovulation during induced oestrus using a CIDR® in trypanotolerant female Bos taurus N'Dama cattle.

The aim of this study was to assess the dose (300 to 600 IU) effects of equine chorionic gonadotropin (eCG) on the preovulatory follicle diameter, growth rate and time of ovulation characterized by echography. The eCG was injected at the end (D0) of the 7-day treatment with a controlled internal device release (CIDR®) and a PGF2α being injected 2 days before the removal of the CIDR® (d-2). The 120 N'Dama female were distributed into five experimental groups. The control group (n = 26) was treated with physiological saline at the removal of the CIDR®, while the animals in the four treated groups received, respectively, 300 IU (n = 25), 400 IU (n = 24), 500 IU (n = 22) and 600 IU (n = 23) of eCG. The diameter of the preovulatory follicle was significantly higher (P < 0.05) in the animals treated with 300 IU (10.1 ± 1.4 mm) than in untreated animals (9.3 ± 1.2 mm). Follicle growth rate was significantly (P < 0.05) higher in treated animals (1.0 ± 0.4 mm/day) than in the control group (0.9 ± 0.4 mm/day). The average interval between the time of eCG injection and ovulation was similar in the non-treated (83.7 ± 14.4 h) and treated animals (79.7 ± 11.9). Treated animals showed a significant increase in the percentage of ovulation (94.7 % compared to 73.1 %) (P < 0.01). Use of eCG contributed towards synchronising the time of ovulation between 72 to 96 h, which would facilitate the use of systematic insemination.

Differential expression of poliovirus receptor, regulator of G-protein signaling 11 and erythrocyte protein band 4.1-like 3 in human granulosa cells during follicular growth and maturation.

Poliovirus receptor (PVR), regulator of G-protein signaling-11 (RGS11), and erythrocyte protein band-4.1-like 3 (EPB41L3) have been proposed to function in follicular maturation in mouse models. We have examined their expression in human mural (mGCs) and cumulus granulosa cells (CCs). Expression of PVR and RGS11 in mGCs decreased in medium-sized follicles compared to small follicles of IVM cycles and increased again in large follicles. Luteinization caused decreased expression of both PVR and RGS11. In vitro incubation of mGCs with progesterone-rich conditioned media decreased expression of RGS11 without affecting PVR levels. Inhibition of progesterone signaling enhanced expression of both RGS11 and PVR. Expression in CCs was examined by means of global transcriptome sequencing analysis RGS11 and EPB41L3 increased in CCs during follicular maturation while PVR levels did not change. In conclusion, during human follicular maturation there are significant changes in expression of PVR, RGS11 and EPB41L3, possibly regulated by progesterone.

Involvement of somatotrophic hormones in the postpartum regulation of ovarian activity in mares.

Mares resume ovarian activity rapidly after foaling. Besides follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the pituitary synthesizes prolactin and growth hormone which stimulate insulin-like growth factor (IGF) synthesis in the liver. We tested the hypothesis that follicular growth is initiated already antepartum, mares with early and delayed ovulation differ in IGF-1 release and that there is an additional IGF-1 synthesis in the placenta. Plasma concentrations of LH, FSH, IGF-1, IGF-2, activin and prolactin. IGF-1, IGF-2, prolactin and their receptors in placental tissues were analyzed at the mRNA and protein level. Follicular growth was determined from 15 days before to 15 days after foaling in 14 pregnancies. Mares ovulating within 15 days postpartum formed group OV (n=5) and mares not ovulating within 15 days group NOV (n=9). Before foaling, follicles with a diameter >1 cm were present in all mares and their number increased over time (p<0.05). Follicle growth after foaling was more pronounced in OV mares (day p<0.001, group p<0.05, day x group p<0.05) in parallel to an increase in LH concentration (p<0.001, day x group p<0.001) while FSH increased (p<0.001) similarly in both groups. Plasma concentrations of IGF-1 and prolactin peaked one day after foaling (p<0.001). The IGF-1 mRNA abundance was higher in the allantochorion but lower in the amnion of OV versus NOV mares (group p=0.01, localization x group p<0.01). The IGF-1 receptor mRNA was most abundant in the allantochorion (p<0.001) and IGF-1 protein was expressed in placental tissue without differences between groups. In conclusion, follicular growth in mares is initiated before foaling and placental IGF-1 may enhance resumption of ovulatory cycles.

The pFSH dose affects the efficiency of in vivo embryo production in Santa Inês ewes.

This study compared the follicular growth, superovulatory response, and in vivo embryo production after administering two doses of porcine follicle-stimulating hormone (pFSH) in Santa Inês ewes. The estrous cycle of 36 multiparous ewes was synchronized with the Day 0 protocol and superovulated with 133 mg (G133, n=18) or 200 mg (G200, n=18) of pFSH. Ultrasonographic evaluations of the ovaries were performed, ewes were mated and submitted to non-surgical embryo recovery. Viable blastocysts were stained with Nile Red and Hoechst. The G200 had a greater number of medium and large follicles, as well as a larger size of the third largest follicle. A total of 97.2% (35/36) of the ewes came into estrus and it was possible to transpose cervix in 80.6% (29/36). There were no effects of treatments in the response to superovulation, the proportion of ewes in which was possible to transpose the cervix, the number of corpora lutea, the number of anovulatory follicles, the proportion of ewes flushed with at least one recovered structure, number of recovered structures, number of viable embryos, viability rate, and recovery rate. The G200 ewes were in estrus for a longer period of time than the G133 ewes (54.0 ± 4.5 h vs. 40.3 ± 3.6 h) and produced more freezable embryos (6.5 ± 1.6 vs. 2.3 ± 0.7) than G133. Both doses promoted an efficient superovulatory response and did not affect embryonic lipid accumulation. The dose of 200 mg of pFSH showed greater potential to increase the superovulatory response, as it increased follicular recruitment and the recovery of freezable embryos.

Impact of antioxidant supplementation during in vitro culture of ovarian preantral follicles: A review.

The in vitro culture systems of ovarian preantral follicles have been developed for studying follicular and oocyte growth, for future use of immature oocytes as sources of fertilizable oocytes and for screening ovarian toxic substances. One of the key limitations of the in vitro culture of preantral follicles is the oxidative stress by accumulation of reactive oxygen species (ROS), which can impair follicular development and oocyte quality. Several factors are associated with oxidative stress in vitro, which implies the need for a rigorous control of the conditions as well as addition of antioxidant agents to the culture medium. Antioxidant supplementation can minimize or eliminate the damage caused by ROS, supporting follicular survival and development and producing mature oocytes competent for fertilization. This review focuses on the use of antioxidants and their role in preventing follicular damage caused by oxidative stress in the in vitro culture of preantral follicles.

Androgen receptor signaling regulates follicular growth and steroidogenesis in interaction with gonadotropins in the ovary during mini-puberty in mice.

In females, androgens contribute to ovarian diseases such as polycystic ovarian syndrome (PCOS), but their action is also crucial for ovarian physiology, i.e., follicular growth and estradiol (E2) synthesis during reproductive life, in interaction with the gonadotropins LH and FSH. However, it is unclear whether androgens already play a role in the ovary at mini-puberty, a phase of postnatal development with active follicular growth and high E2 levels. Therefore, we analyzed the potential actions of androgens on the ovary and their possible interaction with gonadotropins during this period in mice. We used molecular-based studies and pharmacological approaches in vivo and on cultured ovaries. We found that mini-pubertal ovaries produce significant amounts of testosterone and display androgen receptor (AR) expression in growing follicles, both under the control of LH. By blocking AR signaling either in vivo or in ovarian cultures, we found that this pathway may participate in the regulation of prepubertal E2 synthesis and follicular growth, possibly by regulating the expression of a number of key intra-ovarian regulators, including FSH receptor (Fshr), the aromatase enzyme converting androgens into estrogens (Cyp19a1) and the cell cycle inhibitor p27KIP1 (Cdkn1b). We further showed that AR may stimulate FSH-mediated regulation of Cyp19a1 through its action on Fshr mRNA abundance. Overall, this work supports the idea that AR signaling is already activated in mini-pubertal ovaries to regulate E2 synthesis and follicular growth, at the interplay with LH and FSH signaling. Its early action may, thus, contribute to the implementation of early ovarian function with possible impacts on reproductive function.