Advancing fertility preservation in prepubertal mice: Efficacy of ovarian tissue culture and in vitro growth in mature oocyte development.

AIM: This study aimed to evaluate the ovarian tissue culture and in vitro follicle growth as safer alternatives to cryopreservation for generating in vitro fertilization (IVF)-ready mature oocytes from prepubertal mice without the risk of cancer cell contamination. METHODS: Ovaries from prepubertal B6D2F1 mice were cultured in α-minimum essential medium supplemented with an estrogen receptor antagonist, ICI 182780. Culture duration was investigated to identify the optimal timeframe for follicle growth and oocyte maturation. Follicles were isolated mechanically or using 1 mg/mL collagenase and cultured in Matrigel matrix or polyvinylpyrrolidone. Oocyte development at metaphase II was induced by in vitro maturation, followed by IVF. RESULTS: The optimal culture duration was 2-4 days, and tissues cultured beyond this period showed significant follicular degeneration. ICI 182780 supplementation resulted in the recovery of 20.5 follicles per ovary compared with 9.5 follicles in non-supplemented cultures (p < 0.05). Of the 452 isolated follicles, 237 (52.4%) showed growth, 150 (33.2%) underwent germinal vesicle breakdown, and 18 (4.0%) reached metaphase II. However, none of the metaphase II oocytes were successfully fertilized after IVF. Matrigel demonstrated a significantly higher in vitro maturation rate compared with polyvinylpyrrolidone in a comparative analysis of culture matrices (p < 0.001). CONCLUSIONS: This study highlighted ovarian tissue culture and in vitro growth as effective strategies for producing mature oocytes from prepubertal mice. Further studies are required to overcome fertilization hurdles and understand the mechanisms that improve post-IVF embryo viability.

Update on the research on the antigens of anti-sperm antibodies over the last decade.

This review summarizes the advancements over a decade of research on antigens of anti-sperm antibodies (ASAs), which are key to male immune infertility. Despite the progress in assisted reproductive technologies, understanding the roles and mechanisms of ASAs and their antigens remains vital for immune infertility management. We conducted a comprehensive literature search on PubMed from January 2013 to December 2023 using the following keywords: "anti-sperm antibody," "sperm antigen," and "immune infertility." In this review, we focus on the discoveries in sperm antigen identification and characterization through proteomics, gene disruption technology, and immunoinformatics, along with the development of fertility biomarkers. Here, we discuss the clinical applications of improved ASA detection methods and the progress in the development of immunocontraceptive vaccines. The intersection of advanced diagnostic techniques and vaccine development represents a promising frontier in reproductive health. The findings also highlight the need for standardized ASA detection methods and a comprehensive molecular-level approach to understanding ASA-related infertility. These insights underscore the significance of ongoing reproductive immunology research in enhancing clinical fertility outcomes and contraceptive vaccine development.

Anti-tubulin beta 4A (TBB4A) antibody immobilized sperm in a complement-dependent manner in humans.

Sperm-immobilizing antibodies (SI-Abs) are detected in the sera of 3 % of infertile women. SI-Abs are occasionally produced as allogeneic antibodies against sperm, causing immune infertility. SI-Abs inhibit the passage of sperm through the female reproductive tract. Research on anti-sperm antibodies (ASA) remains of great importance for population control. We aimed to identify the antigens recognized by SI-Abs and elucidate the pathogenesis of immune infertility. Twelve sperm-immobilization test (SIT)-positive and fourteen SIT-negative sera were analyzed by two-dimensional electrophoresis and western blotting. Antigenic materials were extracted from well-motile sperm prepared using 0.1 % sodium dodecyl sulfate. In total, 22 different spots were detected in the 12 positive sera. Among these, three positive serum samples showed two positive signals with similar migration patterns. The significant positive spots were Mr: 49 K, pI: 5.1 and Mr: 51 K, pI: 5.6. All these positive spots were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS); tubulin beta-4A (TBB4A) was identified from the spot Mr: 49 K, pI: 5.1. TBB4A is a major component of tubulin and constitutes the axoneme in the sperm tail and the centrosome in the sperm neck; it is generally located inside the cell. An authentic antibody against TBB4A showed a positive reaction in the sperm neck and tail regions in an immunofluorescence study. This antibody also inhibited sperm motility in a complement-dependent manner. Sperm membrane permeability reportedly changes during swimming and capacitation. We identified TBB4A as an antigenic molecule recognized by SI-Abs, which may be relevant to immunological contraception in the future.

Advancements in the detection and implications of sperm-immobilizing antibodies in female infertility.

This review highlights over five decades of research on sperm-immobilizing antibodies (SI-Abs), which are crucial for understanding female infertility due to their effects on sperm motility and fertilization. Since the 1960s, Isojima et al. have made significant strides, notably with the Sperm Immobilization Test (SIT), which revolutionized the quantification of SI-Abs and their roles in infertility. Drawing from a comprehensive PubMed search on "the sperm immobilization test" and "sperm immobilizing antibody," our review underscores the critical insights gained into SI-Abs' impact on reproductive functions. SI-Abs result from the body's response to sperm antigens, potentially leading to infertility by affecting post-intercourse sperm function. However, the presence of anti-sperm antibodies does not guarantee infertility, indicating a complex relationship between these antibodies and reproductive outcomes. Isojima et al.'s pioneering studies paved the way for SIT and sperm immobilization titer (SI50), tools that have clarified the link between SI-Abs and infertility, focusing on disrupted sperm mobility and fertilization as key infertility mechanisms. Clinically, interventions such as in-vitro fertilization (IVF), which bypasses or eliminates SI-Abs, have improved pregnancy rates, whereas Freund's complete adjuvant therapy has deepened our understanding of infertility mechanisms. The SI50 value is crucial for predicting fertility treatment success and guiding therapeutic decisions based on antibody levels. In summary, the evolution of SI-Abs research has provided new hope for addressing infertility, significantly enriching the field of reproductive immunology, and highlighting the need for ongoing investigation.

A case of non-Hodgkin lymphoma of the upper gingiva with minimal residual disease detected in cryopreserved ovarian tissue: A case report.

Recently, more than 200 live births following ovarian tissue cryopreservation (OTC) and transplantation in cancer survivors have been reported worldwide. However, cancer survivors with minimal residual disease (MRD) in cryopreserved ovarian tissue are at the risk of relapse through the graft. Here, we report a rare case of a 19-year-old female patient with non-Hodgkin lymphoma who had MRD in the ovary harvested for OTC. The patient was diagnosed with aggressive B-cell lymphoma after gingival biopsy. The 18F-fluoro-2-deoxy-D-glucose positron emission tomography scan performed before OTC showed no viable lesions in either ovary. However, on histological evaluation, we detected infiltration of lymphoma cells in the ovary. Informed consent about MRD is required even if there is no evidence of MRD in the ovary before OTC. Patients whose cryopreserved ovaries have MRD may require the development of alternative assisted reproductive technologies such as in vitro growth or artificial ovary.

Possible Role of 5-Hydroxytryptamine (5-HT) Receptor on Human Sperm Motility Regulation.

The purpose of this study is to examine whether 5-hydroxytryptamine (5-HT, also known as serotonin) regulates human sperm motility, focusing on 5-HT receptors. Immunofluorescent staining revealed the existence of seven types of 5-HT receptors with a heterogeneous pattern of reactive sites. In detail, 5-HT1B, 5-HT6, and 5-HT7 were detected in the post-acrosomal and mid-piece regions. The 5-HT2A and 5-HT5A receptors were mainly localized in the equatorial segment. 5-HT3A and 5-HT4 receptors were present in the neck and post-acrosomal regions. When examining the effects of 5-HT receptor antagonists on sperm motility, only the 5-HT2A receptor antagonist significantly reduced sperm motility. This suggests that the 5-HT2A receptor may have a regulatory function in sperm motility. Eventually, progressive motility should be attenuated to penetrate the oocyte for fertilization. The current study indicated heterogenous expression patterns and plausible functions of 5-HT receptors in human sperm.

Weight-Loss Interventions and Levonorgestrel Intrauterine System Implantation for Early-Stage Endometrial Cancer and Atypical Endometrial Hyperplasia to Reduce Perioperative Risk of Severely Obese Patients.

Endometrial cancer (EC) and atypical endometrial hyperplasia (AEH) are associated with obesity, which increases the perioperative morbidity and surgical difficulties in laparoscopic and robotic surgery. Weight-loss interventions (WLIs) are likely to reduce morbidity; however, delayed surgery may cause cancer progression. To minimize the tumor progression, levonorgestrel intrauterine system (LNG-IUS) with minimal side effects was used until the planned surgery. During 2016 and 2021, we conducted preoperative management of WLI using LNG-IUS for seven highly obese women with a body mass index (BMI) ≥35 kg/m2 who had AEH and EC with Grade 1 and no myometrial invasion on magnetic resonance imaging. In three of the seven patients, the BMI decreased by more than 5. Two patients with AEH achieved remission after LNG-IUS placement and requested conservative management. Five patients with EC underwent laparoscopic hysterectomy, without perioperative complications.

Management of Hypervascular Retained Products of Conception With Massive Bleeding.

Retained products of conception (RPOC) could be a factor for massive postpartum hemorrhage; however, a management protocol is yet to be established. Performing a surgical intervention is controversial due to the potential for natural healing. Herein, we report the management of a hypervascular RPOC case with massive bleeding. Abortion was performed in a 40-year-old patient with gravida 2 and para 0, at 20 weeks and five days of gestation following the detection of Down's syndrome on prenatal screening. Post-delivery transvaginal ultrasonography identified an intrauterine mass measuring 4cm × 5cm × 5cm. The patient was then followed up in the outpatient department. One month after the abortion, the patient developed abnormal vaginal bleeding. Transvaginal ultrasonography revealed a hypervascular myometrial RPOC with turbulent flow. Although the bleeding stopped upon her admission to our hospital, the patient developed recurrent abnormal vaginal bleeding after nine days of hospitalization, which resulted in a hemoglobin level drop to 5.9 g/dL. CT and MRI scan findings raised the suspicion of hypervascular RPOC or uterine artery pseudoaneurysm. Uterine artery embolization was performed, leading to diminished vascularity in the RPOC, which was confirmed through color Doppler ultrasonography. The remnant placenta was successfully resected hysteroscopically, and a subsequent transvaginal ultrasonography showed a decrease in blood flow. In conclusion, hypervascular RPOC, previously reported as uterine artery pseudoaneurysms, should be considered when detecting hypervascular myometrial lesions in postpartum ultrasonography. Hypervascular RPOC with hemorrhage might benefit from hysteroscopic resection after achieving hemostasis with uterine artery embolization. This case report highlights the potential risks of awaiting spontaneous resolution in large RPOC and suggests that timely surgical intervention is both effective and essential.

Fertility-sparing management of stage IIIC serous borderline ovarian tumor: A case report of a 20-year follow-up.

Multimodal treatment, including assisted reproductive technology, is necessary in young patients with advanced borderline ovarian tumors. However, the details of long-term follow-up cases have not been reported. In this report, a 19-year-old patient presented with a stage IIIC serous borderline tumor. The patient underwent five fertility-sparing surgeries. The tumor did not respond to any of the three lines of chemotherapy administered. Serological and radiological responses were observed following hormonal treatment with leuprorelin, followed by a fourth surgery. Before the planned fifth surgery for complete resection of both adnexa, cryopreservation of the fertilized eggs was performed. At age 36, when the disease-free interval exceeded the previous one, we proposed embryo transfer; however, she declined fertility treatment. The patient had developed rheumatoid arthritis and childbirth not a priority. The patient had lived without any evidence of disease for 7 years following the last surgery and 20 years after the initial visit.

Primordial follicles remaining in young cancer survivors who received chemotherapy.

AIM: Ovarian tissue cryopreservation (OTC) is performed for fertility preservation in cancer patients undergoing chemotherapy. Although anti-Müllerian hormone is used as a marker for ovarian reserve, serum levels do not always correlate with the number of follicles. Additionally, the follicle development stage most affected by chemotherapy is unclear. We examined the association between serum anti-Müllerian hormone levels and the number of remaining primordial follicles after chemotherapy, as well as which follicle stage is most affected by chemotherapy before ovarian cryopreservation. METHODS: Thirty-three patients who underwent OTC were divided into the chemotherapy (n = 22) and non-chemotherapy (n = 11) groups; their ovarian tissues underwent histological examination. Pathological ovarian damage induced by chemotherapy was assessed. Ovarian volumes were estimated from weights. We compared the number of follicles at each developmental stage as a percentage of primordial follicles between the groups. The relationship between serum anti-Müllerian hormone level and primordial follicle density was analyzed. RESULTS: The chemotherapy group had a significantly lower serum anti-Müllerian hormone level, ovarian volume, and density of developing follicles than the non-chemotherapy group. Serum anti-Müllerian hormone levels correlated with primordial follicle density only in the non-chemotherapy group. The chemotherapy group had significantly lower numbers of primary and secondary follicles. CONCLUSIONS: Chemotherapy induces ovarian damage and follicle loss. However, serum anti-Müllerian hormone level does not always reflect the number of primordial follicles after chemotherapy, and chemotherapy more significantly affects primary and secondary follicles than primordial follicles. Many primordial follicles remain in the ovary after chemotherapy, supporting OTC for fertility preservation.

Characterization of a spontaneously occurring self-reactive antibody against sperm in mice.

We previously established a spontaneously occurring monoclonal antibody, namely Ts3, that was reactive to sperm from an aged male mouse. The present study investigated the characteristic properties and reproductive functions of Ts3. Immunofluorescent staining revealed that Ts3 reacted to epididymal sperm, and the corresponding antigen was located in the midpiece and principal piece. Immunohistochemistry revealed positive reactions in the germ cells and Sertoli cells in the testis, the epithelial cells in the epididymis and vas deferens. Through western blotting with two-dimensional electrophoresis, we demonstrated that Ts3 reacted with four spots, which were around Mr ∼25,000-60,000 and pI 5-6. MALDI-TOF/TOF mass spectrometry identified outer dense fiber 2 (ODF2) as a candidate for Ts3. ODF2 is a cytoskeletal structural component located in the midpiece and principal piece of the flagella of mammalian sperm. This was validated with the result of immunofluorescent staining, suggesting that ODF2 was the main target antigen for Ts3. Sperm immobilization test showed that Ts3 possessed sperm immobilizing activity. Furthermore, Ts3 impaired early embryo development but not in vitro fertilization. These results suggest that ODF2 plays an important role in both sperm function and early embryonic development.

Metronomic chemotherapy using oral cyclophosphamide and bevacizumab for recurrent cervical cancer: A multi-institutional retrospective study.

No standard chemotherapy is available after disease progression or anaphylaxis during platinum chemotherapy among patients with recurrent cervical cancer. Here we report the efficacy and toxicities of metronomic chemotherapy consisting of 50 mg of oral cyclophosphamide (CPA) daily and intravenous 15 mg/kg of bevacizumab (BEV) repeated every 3 weeks (CPA-BEV). Treated patients were retrospectively reviewed. Adverse events and response rates were recorded according to the Common Toxicity Criteria for Adverse Events (CTCAE) ver 5.0 and Response Evaluation Criteria In Solid Tumors ver 1.1, respectively. Eleven patients had been treated with CPA-BEV between 2016 and 2021.The pathologic types were squamous cell carcinoma in seven patients, adenocarcinoma in three, and large cell neuroendocrine carcinoma in one. Nine patients had primary concurrent chemoradiotherapy (CCRT). Five patients received more than one prior chemotherapy (excluding CCRT). Six patients had progressive disease during prior platinum-based chemotherapy, four patients recurred within 6 months of the last platinum administration, and one patient had platinum anaphylaxis. Grade 3 or more hematologic toxicities and grade 2 or more non-hematological toxicities were observed in one with grade 3 neutropenia and in one with grade 2 proteinuria, respectively. The median duration of chemotherapy was 2.8 months (range 0.2-30.6 months). One patient had CR but none had PR. Median progression-free survival was 2.8 months (95 %CI: 2.1-10.7 months), and median overall survival was 13.6 months (95 %CI: 8.4-33.7 months). In conclusion, the CPA-BEV regimen showed favorable antitumor activity with minimal toxicity and is promising candidate for second-line chemotherapy.

Evaluation of NKp46 expression and cytokine production of decidual NK cells in women with recurrent pregnancy loss.

Purpose: NKp46, a receptor on NK cells, is involved in cytotoxicity and cytokine production. The authors aimed to evaluate the effect of NKp46 on decidual NK (dNK) cells during pregnancy and whether it can be a marker for immunological abnormalities in women with recurrent pregnancy loss (RPL). Methods: Flow-cytometric analysis was made to assess NKp46 expression and intracellular cytokine production of dNK cells. The proportion of NKp46+ dNK cells was analyzed among RPL patients who aborted karyotypically normal pregnancies and those who either aborted karyotypically abnormal pregnancies or without genetic studies, and controls who were going through the induced abortion. Results: The %NKp46+ and %NKp46bright dNK cells were significantly lower in the RPL women who aborted karyotypically normal pregnancies than in the control group. The %NKp46bright dNK cells were significantly correlated with the NK1/NK2 ratio of dNK cells. The %NKp46+ dNK cell cutoff for RPL with immunological abnormalities was determined by the ROC curve analysis. In women with the low %NKp46+ dNK, NK1/NK2 ratios were significantly higher than those with the high. Conclusion: RPL patients with an immunological abnormality have decreased NKp46 expression and NK1 shift in dNK cells. NKp46 expression could be a marker for RPL of immunological abnormalities.

Sex difference in anti-sperm antibodies.

Background: Some diseases have sex differences. There have been no reports on the relationship between anti-sperm antibodies (ASA) and sex differences. Methods: ASA are detected by sperm-immobilization test using patients' sera in women. In men, the ASA testing is generally performed by direct-immunobead test. Main findings: Sperm-immobilizing antibodies in women inhibit sperm migration in their genital tract and exert inhibitory effects on fertilization. ASA bound to sperm surface in men also show inhibitory effect on sperm passage through cervical mucus. The fertilization rate of IVF significantly decreased when sperm were coated with higher numbers of ASA. For women with the antibodies, it is important to assess individual patients' SI50 titers. In patients with continuously high SI50 titers, pregnancy can be obtained only by IVF. For men with abnormal fertilizing ability by ASA, it is necessary to select intracytoplasmic sperm injection. Production of sperm-immobilizing antibodies is likely to occur in women with particular HLA after exposure to sperm. The risk factors for ASA production in men are still controversial. Conclusion: Attention to sex differences in specimens, test methods and the diagnosis of ASA should be paid. For patients with ASA, treatment strategies have been established by considering sex difference for each.

NK cells that differ in expression of NKp46 might play different roles in endometrium.

NKp46 is a natural cytotoxicity receptor expressed by NK cells and its expression is decreased in reproductive failure patients. NKp46 can be subdivided into NKp46dim and NKp46bright according to different fluorescence staining intensities. We investigated the role of the NKp46 receptor in determining the reproductive outcomes. Uterine endometrium was collected from 34 women with reproductive failure and divided into the pregnant and failed groups based on the results of a pregnancy reaction test during a 1-year follow-up period. NKp46 receptor and other activating or inhibitory receptors expressed on NK cells as well as intracellular cytokine production by NK cells were analyzed by multicolor flow cytometry. In the failed group, the percentage of NKp46dim NK cells (P < 0.05) was significantly higher and percentages of NKp46bright NK cells (P < 0.01) and CD16-/CD56bright NK cells (P < 0.05) were significantly lower than those in the pregnant group. NKp46dim NK cells were significantly and positively correlated with CD16+/NKp46dim NK cells; NKp46bright NK cells were significantly and positively correlated with CD16-/NKp46bright NK cells. CD16+/NKp46dim NK cells were significantly and positively correlated with IFN-γ- and/or TNF-α-producing NK cells; CD16-/NKp46bright NK cells were significantly and positively correlated with TGF-ß1-producing NK cells. We suggest that the NKp46 receptor plays different roles in reproduction based on the different fluorescence intensities associated with NK cells, i.e. NKp46dim NK cells are involved in killing cells, whereas NKp46bright NK cells are involved in cytokine production, indicating that NKp46 could be a predictive marker to see a tolerate condition for embryos.

Sperm immobilization test and quantitative sperm immobilization test using frozen-thawed sperm preparation applied with computer-aided sperm analysis.

PURPOSE: In a previous study, a new method was described using the sperm immobilization test (SIT) with computer-aided sperm analysis (CASA). However, obtaining high-quality sperm as needed was a known issue. Here, we compared the results of using frozen-thawed sperm and fresh sperm for the SIT using the CASA method. METHODS: For the frozen-thawed preparation, 500 µL of condensed semen and 500 µL of Sperm Freeze were mixed in a cryovial and cryopreserved in liquid nitrogen. Density gradient centrifugation was used for the collection of motile sperm in both the fresh and frozen-thawed sperm preparations. A total of 50 serum samples were prepared for both the fresh and frozen-thawed sperm with each sample tested containing 10 µL of serum, 1 µL of either fresh or frozen motile sperm suspension, and 2 µL of complement. Sperm motilities were measured using CASA after a 1-hour incubation period for both fresh and frozen-thawed sperm. RESULTS: Both fresh and frozen-thawed sperm reacted similarly when exposed to serum containing sperm-immobilizing antibodies asserting the use of frozen-thawed sperm for the diagnosis of immunological infertility. CONCLUSION: These results suggest the possibility of using cryopreserved sperm for the SIT when fresh sperm is unavailable.

The chronological change in transvaginal ultrasound images of a hemorrhagic ovarian cyst observed during infertility treatment: A case report and literature review.

Insights gained from chronological ultrasonogram images in the current case report will provide useful information for diagnosing and conservatively treating HOC. This could help avoid unnecessary laparotomy.

Use of cryopreserved ovarian tissue in the Danish fertility preservation cohort.

OBJECTIVE: To evaluate the use of cryopreserved ovarian tissue in the Danish fertility preservation cohort. DESIGN: Retrospective cohort study. SETTING: University hospitals and fertility clinics. PATIENT(S): Ovarian tissue cryopreservation (OTC) was performed for 1,186 Danish girls and women from 1999-2020, of whom 117 subsequently underwent ovarian tissue transplantation (OTT). Subgroup 1 included 759 patients with a follow-up period of >5 years. Out of these, OTT rates were further analyzed for those patients who were alive and aged >24 years in July 2020 (subgroup 2; n = 554). INTERVENTION(S): OTC and OTT. MAIN OUTCOME MEASURE(S): OTT, death, donation of tissue. RESULT(S): In subgroup 1, 14% of the patients had undergone OTT, 18% had died, 9% had donated their tissue for research, and 59% still had their tissue stored. In subgroup 2, 19% had undergone OTT and for most diagnoses the OTT rates ranged from 15% to 22% with benign hematologic diseases having the highest OTT rate (35%). On the basis of the entire cohort, stratified age analysis indicated that women aged ≥30 years at OTC were more likely to return for OTT than women aged 18-29 years at OTC; mean storage times were 3.7 and 3.6 years, respectively. Only 4% of the girls aged <18 years at OTC had undergone OTT. CONCLUSION(S): The OTT rates depended on the diagnosis, age at OTC, and follow-up time. Specific criteria are needed for reporting and comparing OTT rates. Six out of 10 patients still had their cryopreserved tissue stored and longer follow-up is needed, especially for younger girls.

Clusters of smooth endoplasmic reticulum are absent in oocytes from unstimulated women.

RESEARCH QUESTION: What is the frequency of morphological dysmorphisms in immature human oocytes collected ex vivo from small antral follicles and matured in vitro? DESIGN: Human ovaries (n = 56) were excised for ovarian tissue cryopreservation (OTC). None of the patients had received exogenous gonadotrophins prior to the procedure. Immature oocytes released from small antral follicles were collected in connection with isolation of the cortex for OTC. The oocytes' maturation stage and the morphological characteristics of the cytoplasm, zona pellucida, perivitelline space and first polar body were assessed after in-vitro maturation (IVM). RESULTS: A total of 1649 immature oocytes were collected: 30% of oocytes matured to the metaphase II (MII) stage after IVM, while metaphase I (MI), germinal vesicle and degenerated oocytes accounted for 20%, 24% and 26%, respectively. The percentages of oocytes without any dysmorphisms were 53%, 92%, and 97% for the MII, MI and germinal vesicle stage oocytes, respectively. The most frequently observed dysmorphisms among the MII oocytes were first polar body fragmentation (22%), homogeneously distributed cytoplasmic granularity (16%) and an enlarged perivitelline space (14%). Interestingly, none of the oocytes at any stage had clusters of smooth endoplasmic reticulum (SER). CONCLUSIONS: Morphological dysmorphisms are present among in-vitro-matured oocytes at all maturation stages. The incidence of dysmorphisms increases as maturation progresses. The most frequent dysmorphism among MII oocytes after IVM was fragmentation of the first polar body. Clusters of SER were not observed in oocytes from unstimulated patients.

A threshold concentration of FSH is needed during IVM of ex vivo collected human oocytes.

PURPOSE: To investigate the effect of different FSH concentrations on human oocyte maturation in vitro and its impact on gene expression of key factors in the surrounding cumulus cells. METHODS: The study included 32 patients who underwent unilateral oophorectomy for ovarian tissue cryopreservation (OTC) (aged 28 years on average). Immature oocytes were collected from surplus medulla tissue. A total of 587 immature oocytes were divided into three categories according to the size of the cumulus mass: large (L-COCs), small (S-COCs), and naked oocytes (NOs), and submitted to 44-h IVM with one of the following concentrations of recombinant FSH: 0 IU/L, 20 IU/L, 40 IU/L, 70 IU/L, or 250 IU/L. After IVM, oocyte nuclear maturation stage and diameter were recorded. The relative gene expression of FSHR, LHCGR, and CYP19A1 in cumulus cells before (day 0; D0) and after IVM were evaluated. RESULTS: Addition of 70 or 250 IU/L FSH to the IVM medium improved oocyte nuclear maturation compared to 0, 20, and 40 IU/L FSH by upregulating LHCGR and downregulating FSHR in the cumulus cells. CONCLUSION: FSH improved oocyte nuclear maturation at concentrations above 70 IU/L suggesting a threshold for FSH during IVM of ex vivo collected human oocytes from small antral follicles. Moreover, current results for the first time highlight that FSH function in vitro is mediated via cumulus cells by downregulating FSHR and upregulating LHCGR, which was also observed when the immature oocytes progressed in meiosis from the GV to the MII stage.