Cumulus-oocyte Complexes Research Articles

O-303 What is the ideal dose of daily FSH after corifollitropin-alfa? A multicentre-randomized control trial

Abstract Study question Does the mean serum trigger-progesterone levels show significant variation based on the administered rFSH dose from day 8 onwards during ovarian stimulation using corifollitropin-alfa? Summary answer Lower rFSH doses from day 8 of ovarian stimulation onwards are linked to reduced serum progesterone (P4) levels without impact on cumulus-oocyte complexes. What is known already Progesterone elevation during ovulation trigger prompts a non-elective freeze-all strategy, given the lower live birth rates in fresh embryo transfers. Ongoing research explores methods to mitigate late follicular phase P4 rise to allow a fresh embryo transfer. Granulosa cells’ progesterone production is an FSH-driven and dose-dependent process, and FSH dose is furthermore pivotal for a good ovarian response. Balancing FSH dose is crucial for both optimal ovarian response and preventing undesirable P4 elevation while maintaining an adequate number of retrieved oocytes and allowing a fresh embryo transfer. Study design, size, duration This study is an interim-analysis of a randomized-controlled multi-center clinical-trial comparing three ovarian-stimulation-protocols: (A) corifollitropin alfa (CFA) followed by rFSH 50 IU/day; (B) CFA followed by rFSH 150 IU/day; (C) CFA followed by rFSH 250 IU/day.The primary outcome is the serum-progesterone-level on the day of hCG among the study groups, secondary outcomes included number of oocytes, clinical pregnancy rates and freeze-all cycles. 167 women (of 261) were randomized between July 2019-November 2023, with a 1:1allocation. Participants/materials, setting, methods Young (<40 years old), normo-ovulatory cycle (25-35 days), with AFC>7 and <20, and a BMI<29 Kg/m2 patients were recruited in the fertility clinic of three different tertiary university hospitals. On day 8 of ovarian stimulation (OS) following CFA administration, patients who needed additional rFSH were randomized into 3 groups (A-B-C). The OS was performed in a GnRH-antagonist protocol and the ovulation triggered with hCG. A fresh embryo-transfer was performed on day 5 following oocyte retrieval. Main results and the role of chance Overall, 167 patients were randomized, 60 in group A, 55 in group B and 52 in group C. The mean age and BMI were comparable between the groups. Mean AMH was respectively 2.2, 2.1 and 2.2 ng/mL, for group A, B and C (p = 0.95). Group A resulted in a significantly lower P4 level at trigger as compared with group B and C (respectively, 0.4ng/mL, 0.9 ng/mL and 1.4 ng/mL; p < 0.001). The mean number of retrieved oocytes was 10.7, 11 and 12.1 for group A, B and C, respectively (p = 0.47), while the mean number of mature oocytes was 7.3, 6.9 and 7.8 for group A, B and C, respectively (p = 0.7). A freeze-all approach was decided for 27%, 29% and 46% for group A, B and C respectively (p = 0.057). No significant differences were found for fresh-embryo-transfer outcomes (chemical pregnancy rates: 33%, 31% and 29%, respectively for A, B and C (p = 0.12).Of interest, comparisons between serum FSH at trigger showed a mean of 12.5, 17 and 20.5 IU/L for group A, B and C, respectively (p < 0.001) while the serum estradiol levels on day of trigger were comparable among the groups (1659, 2092 and 2098 ng/L for group A, B and C, respectively (p = 0.091). Limitations, reasons for caution This is an interim analysis planned to detect the mean difference in COC between groups. Therefore, the mean differences of the primary outcome should be interpreted as exploratory findings which warrant future investigation. Wider implications of the findings Administering a lower rFSH dose from day 8 onward during ovarian stimulation results in comparable numbers of COC but also leads to significantly lower serum P4 levels. Consequently, this finding has the potential to reduce the overall consumption of rFSH, thereby possibly increasing the likelihood of a fresh embryo transfer. Trial registration number NCT03686852

P-607 Reproductive outcomes of oocyte donors using subdermal etonogestrel implants and levonorgestrel intrauterine devices

Abstract Study question Does the use of progesterone contraceptive devices during controlled ovarian stimulation (COS) affect ovarian response in oocyte donation cycles? Summary answer Progesterone contraceptive devices during COS did not impact ovarian response, measured by oocyte retrieval and maturity rates, in oocyte donation cycles. What is known already Subdermal etonogestrel implants and levonorgestrel intrauterine devices (L-DIU) are widely used contraceptives amongst oocyte donors. While the safe and effective use of L-DIU during COS has been documented, the impact of subdermal etonogestrel implants on ovarian response is less understood. Given their distinct mechanisms of action and varying local and systemic pharmacodynamics, a comprehensive understanding of the impact of these contraceptives on ovarian response during COS will be crucial for guiding informed clinical practice. Study design, size, duration In this retrospective cohort study, we analyzed 3,452 heterologous ICSI cycles from 1,975 oocyte donors (18-35 years), performed between March 2021 and September 2023, across two centers. We identified 40 COS in donors using contraceptive devices, either a subdermal etonogestrel implant (n = 18) or L-DIU, (n = 22). These were matched with 80 COS without a device. We primarily compared ovarian response amongst the two groups. Secondary outcomes included biochemical pregnancy, clinical pregnancy and live birth rates. Participants/materials, setting, methods We applied a propensity matching score model (PsmPy package, Python), trained on 3,388 oocyte donation cycles, for matching donors with and without contraceptive devices. Matching was based on age, BMI, anti-müllerian hormone (AMH) and antral follicle count (AFC), maintaining a 1:2 ratio. Ovarian response outcomes (oocyte retrieval and maturation rates) were analyzed using Student’s t-tests, while and clinical outcomes were evaluated using Fisher’s exact test. P-values <0.05 were considered significant. Main results and the role of chance Mean age was 26.22, BMI 24.7, AMH 2.63 ng/ml and AFC 18.77. We evaluated a total of 120 COS, leading to 176 heterologous ICSI cycles. The oocyte retrieval rate (total number of cumulus-oocyte-complexes (COCs) per total number of follicles > 14mm at final follicular scan), averaged 109.64%. We observed no differences in the number of COCs retrieved from donors with and without contraceptive devices (17.5 ±7.6 and 18.5 ± 9.6, respectively). Similarly, oocyte maturation rates (total number of MII oocytes per total number of COCs), were comparable amongst the two groups (78.6% overall, 77.6% with contraception device and 79.1% without contraception device, p > 0.05). The presence of the device did not affect biochemical pregnancy (69.7% with contraceptive device, 61.1% without contraceptive device, p > 0.05), clinical pregnancy (54.6% with contraceptive device, 52.9% with contraceptive device, p > 0.05) and ongoing pregnancy (36.4% with contraceptive device, 35.3% without contraceptive device). These results were consistent regardless of the type of device used. Limitations, reasons for caution The main limitation is the retrospective nature of the study, potentially influencing causal inferences, and that both devices were analyzed as one same group. The small subset of COS with contraceptive devices may impact statistical power. Perinatal outcomes were not analyzed. Wider implications of the findings This research provides clinicians with reassurance that the use of progesterone contraceptive devices during COS does not adversely affect clinical outcomes. These findings offer valuable insights for patient counseling, affirming the safety of contraceptive methods and encouraging further research for a more comprehensive understanding in diverse populations and clinical settings. Trial registration number not applicable

O-190 Hormone-free versus FSH-primed infertility treatment of women with polycystic ovary syndrome using biphasic in vitro maturation: a randomised clinical trial

Abstract Study question Is any hormone stimulation needed to treat infertility in women with polycystic ovary syndrome (PCOS) using in vitro maturation (IVM)? Summary answer Number of matured oocytes and pregnancy outcomes were similar without or with FSH-priming in women with PCOS undergoing IVM. What is known already In vitro maturation (IVM) is a low-intervention alternative to in vitro fertilisation (IVF) for infertility treatment. Current standard clinical practice for human IVM is to prime patients for 2–5 days with follicle-stimulating hormone (FSH) and/or human chorionic gonadotropin (hCG) before harvesting immature or mixed maturity oocytes for infertility treatment. This gonadotropin priming is thought necessary to induce sufficient follicle and oocyte development in vivo to support subsequent oocyte maturation and embryo development in vitro when using a single step (monophasic) oocyte maturation culture system. It is not clear whether hormone-free IVM can generate satisfactory pregnancy and live birth rates. Study design, size, duration This randomised, controlled trial was conducted at an tertiary IVF center, Ho Chi Minh City, Viet Nam. Between January 2023 and June 2023, 120 women (60 per group) were randomised. Participants/materials, setting, methods Eligible women were aged 18–37 years and had PCOS with an indication for biphasic capacitation-IVM (CAPA-IVM). After providing written informed consent, participants were randomised (1:1) to undergo CAPA-IVM with or without FSH-priming. Participants in the FSH-priming group received two days of FSH injections before oocyte pick-up; no FSH was given in the non-FSH group. After CAPA-IVM, day-5 embryos were vitrified for transfer in a subsequent cycle. The primary endpoint was number of matured oocytes. Main results and the role of chance The number [interquartile range] of matured oocytes after CAPA-IVM did not differ significantly between the non-FSH and FSH groups (13 [9; 18] vs. 14 [7; 18]; absolute difference –1 [95% confidence interval –5, 4]). There were also no significant between-group differences in other oocyte and embryology outcomes, including the number of cumulus-oocyte complexes, number of fertilized oocytes, total number of blastocysts and good blastocysts, and total number of frozen embryos. No between-group differences were found in the rates of ongoing pregnancy and live birth, which were both 38.3% in the non-FSH group and both 31.7% in the FSH group; the miscarriage rate at < 12 weeks’ gestation was 5.0% in both groups. Maternal complications were infrequent and occurred at a similar rate in the non-FSH and FSH groups; there were no preterm deliveries before 32 weeks’ gestation. Limitations, reasons for caution The characteristics of the study population (relatively young, lean women with PCOS from Viet Nam) limit the external generalisability of the study findings, and the findings need to be replicated in other populations. Wider implications of the findings Hormone-free assisted reproductive technology (ART) for women with PCOS appears to be feasible when using CAPA-IVM, and does not result in any loss of clinical efficacy. Benefits of hormone-free ART would be a reduction in medical risk, lower cost, fewer monitoring requirements, and greater convenience and flexibility. Trial registration number NCT05600972

P-260 In Vitro Fertilization (IVF) using magnetotactic sperm cells and their prospects for assisted in vivo reproduction

Abstract Study question Are bovine Magnetotactic Sperm Cells (MSC) able to fertilize an oocyte in-vitro and Which would be the main requirements for translating this technology to in-vivo? Summary answer IVF using highly purified MSC result in embryo development until blastocyst stage. We demonstrate different alternatives to control multiple MSC, individually and as a swarm. What is known already Medical microrobots have appeared as the new generation of drug delivery vehicles. They are tiny devices in the order of a few micrometers, able to move in biological environments by different means, physical, chemical, or biohybrid. They are functionalized to deliver targeted therapies for drugs, cells, or other payloads. In assisted reproduction, sperm-hybrid microcarriers have been pioneered by our group, and various in vitro demonstrations have been done to assist sperm cells with motion deficiencies or low count and to deliver anticancer drugs for treating, for example, cervical and ovarian cancer, but so far in-vitro fertilization has never been shown. Study design, size, duration Experimental quantitative study design. A total of 520 bovine cumulus-oocyte complexes were used for in vitro fertilization. The analyzed sample groups were using bovine frozen sperm cells, MSC, or by evaluating parthenogenetic activation. A power of 0.98 with an a-error of 0.05 was used for the IVF experiments. Sperm samples in the control as well as the micromotor groups have been analyzed for different sperm parameters. Participants/materials, setting, methods Bovine MSC are created by thawing frozen sperm cells and adding polystyrene microparticles. Different sperm parameters were evaluated to check the effects of the particles in the cells. After developing a purification method for the MSC, bovine ovaries were collected from a slaughterhouse nearby and, after in vitro maturation, were used for the IVF experiments. Ultrasound, and photoacoustic imaging setups with a set of electromagnets were employed for real-time manipulation and visualization of MSC. Main results and the role of chance Sperm viability was significantly higher in the MSC group compared to the control group 6h after formation (72.3 ± 5.0% vs 35.0 ± 4.1%), and after 24 hours, both viabilities decreased drastically to 16.6 ± 3.9% and 7.7 ± 1.7% respectively, probably a possible local antioxidant effect by the microparticles through the formation of a protein corona. In the case of motility, the MSC group presented significantly higher motility up to 6h (64.0 ± 1.5%), and in all the measured times, the motility of the MSC group was higher than the control group. Purification of the micromotor sample was performed, but an average of 63 free sperm was still on the MSC sample. IVF experiments were performed, and blastocyst development was observed in IVF control (2x106 sperm/ml), medium concentration (same concentration as MSC group), and the MSC groups (275.000 sperm/ml). No blastocyst formation was observed in the parthenogenetic, parthenogenetic + particles, and low-concentration groups (number of free sperm). The MSC group was significantly different in cleavage and blastocyst rates compared to the low concentration groups, with p-values of 0.04552 and 0.005865, respectively, which suggest that fertilization may have occurred by the micromotors instead by the free sperm in the sample. Limitations, reasons for caution More studies of these MSC in the different gynecological tissues and on embryo development are needed to ensure the safety of future human translation. In addition, developing a detection system for micromotors in deep tissue is needed to perform in vivo experiments. Wider implications of the findings MSC show an alternative to efficiently guide efficiently sperm cells in different biological environments and can be a promising alternative method for assisted fertilization, and the treatment of a variety of gynecological diseases. They can also be used as exploratory tools to learn more about sperm migration in-vivo, among others Trial registration number European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program No. 853609

LPS-Induced Mitochondrial Dysfunction Reduces Oocyte Maturation and Developmental Competence of Buffalo Embryos via ROS Mediated TLR4 Signalling.

Lipopolysaccharide (LPS) from gram-negative bacteria has reportedly been associated with infectious diseases like metritis, which has a substantial adverse effect on animal reproductive performance and causes serious financial losses for the dairy sector. The current work aimed to establish the impact of LPS on in vitro oocyte maturation and subsequent in vitro developmental competence of oocytes, as well as to investigate the explanatory molecular mechanism underlying this effect. Buffalo cumulus-oocyte complexes (COCs) were challenged with 0, 5, 10 and 20 µg/mL LPS during IVM followed by IVF and IVC. Cytoplasmic and nuclear maturation, cleavage and blastocyst rate, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP, ΔΨm) and transcript abundance of genes related to inflammation, antioxidation and apoptosis were evaluated. The maturation and subsequent embryonic development competency were found to be significantly (p≤0.05) reduced with the addition of 10 and 20µg/mL LPS to IVM media. ROS production accompanied by a decreased ΔΨm was recorded in LPS-treated oocytes in comparison to the control group (p≤0.05). Our results were further supported by the transcriptional expression of proinflammatory (TLR4, CD14 and RPS27A) and apoptotic gene (Caspase 3) which were found to be significantly increased while antioxidant genes (SOD2 and GPX1) were decreased significantly in matured oocytes and blastocyst after LPS exposure. The deleterious effects of LPS are mediated through ROS generation, which triggers inflammatory processes via the TLR4 pathway and impairs oocyte maturation and subsequent embryonic development.

In Vitro Embryos of Romosinuano and Tropical Milking Cattle during Three Seasons in Veracruz, Mexico.

One of the main factors that influences the fertility of cattle in grazing systems in hot tropical climates is heat stress. The objective of this study was to evaluate the effect of season, breed, hormonal and physiological condition on the quantity and quality of cumulus-oocyte complexes (COCs) and embryos produced in vitro, from Romosinuano (RM) and Tropical Milking (TM) donors. Three ovum pick-up and in vitro fertilization (OPU-IVF) were performed, one per season: hot dry (HD; 10, 10), hot humid (HH; 9, 9) and fresh dry (FD; 7, 10) in RM and LT donors. Serum levels of cortisol, insulin and glucose were measured, in addition to heart rate (HR), respiratory rate (RR) and rectal temperature (RT). Effect of season x genotype interaction (p ≤ 0.05) was observed in all COC variables and only in cleavage embryos (CLI) (p ≤ 0.05). Body weight (BW) affected all COC variables (p ≤ 0.01), except unviable (UNV) although affected degenerated embryos (DEG) (p ≤ 0.01) and total blastocysts (BLAST) (p ≤ 0.01). Cow age only affected viable COCs (VIAB) (p ≤ 0.05), code one blastocysts (BC1) and BLAST (p ≤ 0.01). Cortisol affected total COCs (COCsT), VIAB and total matured in vitro (TMIV) (p ≤ 0.01), as well as CLI, BC1 (p ≤ 0.01) and BLAST (p ≤ 0.05). Insulin affected COCsT (p ≤ 0.01), UNV (p ≤ 0.05), denuded oocytes (DE) (p ≤ 0.01), BC1 and code two blastocysts (BC2) (p ≤ 0.01). Glucose affected all COC variables (p ≤ 0.01), except UNV and all embryo variables except BC2. HR affected COCsT, DE, TMIV (p ≤ 0.01), CLI, BLAST and DEG (p ≤ 0.05). RR affected COCsT, UNV, VIAB, CLI (p ≤ 0.05), BC1, BLAST and DEG (p ≤ 0.01). RT only affected DE, VIAB (p ≤ 0.01) and BLAST (p ≤ 0.05). The seasonal climatic year variation of Veracruz and changes in physiological and hormonal variables have diverse effects on the cumulus-oocyte complexes and embryos produced by RM and TM donors.

In vitro production of meiotically competent oocytes from early antral follicles in sheep

The potential of using long in vitro culture (LIVC) of cumulus-oocyte complexes (COCs) from early antral follicles (EAFs) as an assisted reproductive technology in cattle has shown promising results. This study explored the feasibility of applying this technology to sheep as seasonal breeding animals. Ovaries from sheep were collected during both the breeding and non-breeding seasons. COCs were isolated from EAFs (350–450 μm) and cultured in TCM199 medium supplemented with 0.15 μg/mL Zn sulfate, 10−4IU/mL FSH, 10 ng/mL estradiol, 50 ng/mL testosterone, 50 ng/mL progesterone, and 5 μM Cilostamide. After five days of LIVC, the COCs were submitted to an in vitro maturation procedure. The results indicate successful in vitro development of COCs, evidenced by a significant increase in oocyte diameter (p < 0.000) and the preservation of gap junction communication between oocyte and cumulus cells. The gradual uncoupling was accompanied by a progressive chromatin transition from the non-surrounded nucleolus (NSN) to the surrounded nucleolus (SN) (p < 0.000), coupled with a gradual decrease in global transcriptional activity and an increase in oocyte meiotic competence (p < 0.000). Maintenance of oocyte-cumulus investment architecture, viability, and metaphase II capability was significantly higher in COCs collected during the breeding season (p < 0.000), suggesting higher quality than those obtained during the non-breeding season. In conclusion, our study confirms LIVC feasibility in sheep, emphasizing increased effectiveness during the breeding season in isolating higher-quality COCs from EAFs. These findings can influence improving the LIVC system in mammals with seasonal reproduction.

Preovulatory follicular fluid secretome added to in vitro maturation medium influences the metabolism of equine cumulus-oocyte complexes

BackgroundIn vitro embryo production is a highly demanded reproductive technology in horses, which requires the recovery (in vivo or post-mortem) and in vitro maturation (IVM) of oocytes. Oocytes subjected to IVM exhibit poor developmental competence compared to their in vivo counterparts, being this related to a suboptimal composition of commercial maturation media. The objective of this work was to study the effect of different concentrations of secretome obtained from equine preovulatory follicular fluid (FF) on cumulus-oocyte complexes (COCs) during IVM. COCs retrieved in vivo by ovum pick up (OPU) or post-mortem from a slaughterhouse (SLA) were subjected to IVM in the presence or absence of secretome (Control: 0 µg/ml, S20: 20 µg/ml or S40: 40 µg/ml). After IVM, the metabolome of the medium used for oocyte maturation prior (Pre-IVM) and after IVM (Post-IVM), COCs mRNA expression, and oocyte meiotic competence were analysed.ResultsIVM leads to lactic acid production and an acetic acid consumption in COCs obtained from OPU and SLA. However, glucose consumption after IVM was higher in COCs from OPU when S40 was added (Control Pre-IVM vs. S40 Post-IVM: 117.24 ± 7.72 vs. 82.69 ± 4.24; Mean µM ± SEM; p < 0.05), while this was not observed in COCs from SLA. Likewise, secretome enhanced uptake of threonine (Control Pre-IVM vs. S20 Post-IVM vs. S40 Post-IVM: 4.93 ± 0.33 vs. 3.04 ± 0.25 vs. 2.84 ± 0.27; Mean µM ± SEM; p < 0.05) in COCs recovered by OPU. Regarding the relative mRNA expression of candidate genes related to metabolism, Lactate dehydrogenase A (LDHA) expression was significantly downregulated when secretome was added during IVM at 20–40 µg/ml in OPU-derived COCs (Control vs. S20 vs. S40: 1.77 ± 0.14 vs. 1 ± 0.25 vs. 1.23 ± 0.14; fold change ± SEM; p < 0.05), but not in SLA COCs.ConclusionsThe addition of secretome during in vitro maturation (IVM) affects the gene expression of LDHA, glucose metabolism, and amino acid turnover in equine cumulus-oocyte complexes (COCs), with diverging outcomes observed between COCs retrieved using ovum pick up (OPU) and slaughterhouse-derived COCs (SLA).

Deregulation of oxidative phosphorylation pathways in embryos derived in vitro from prepubertal and pubertal heifers based on whole-transcriptome sequencing

BackgroundAlthough, oocytes from prepubertal donors are known to be less developmentally competent than those from adult donors it does not restrain their ability to produce full-term pregnancies. The transcriptomic profile of embryos could be used as a predictor for embryo’s individual developmental competence. The aim of the study was to compare transcriptomic profile of blastocysts derived from prepubertal and pubertal heifers oocytes. Bovine cumulus-oocyte complexes (COCs) were obtained by ovum pick- up method from prepubertal and pubertal heifers. After in vitro maturation COCs were fertilized and cultured to the blastocyst stage. Total RNA was isolated from both groups of blastocysts and RNA-seq was performed. Gene ontology analysis was performed by DAVID (Database for Annotation, Visualization and Integrated Discovery).ResultsA higher average blastocyst rate was obtained in the pubertal than in the pre-pubertal group. There were no differences in the quality of blastocysts between the examined groups. We identified 436 differentially expressed genes (DEGs) between blastocysts derived from researched groups, of which 247 DEGs were downregulated in blastocysts derived from pubertal compared to prepubertal heifers oocytes, and 189 DEGs were upregulated. The genes involved in mitochondrial function, including oxidative phosphorylation (OXPHOS) were found to be different in studied groups using Kyoto Encyclopedia of Genes (KEGG) pathway analysis and 8 of those DEGs were upregulated and 1 was downregulated in blastocysts derived from pubertal compared to prepubertal heifers oocytes. DEGs associated with mitochondrial function were found: ATP synthases (ATP5MF-ATP synthase membrane subunit f, ATP5PD- ATP synthase peripheral stalk subunit d, ATP12A- ATPase H+/K + transporting non-gastric alpha2 subunit), NADH dehydrogenases (NDUFS3- NADH: ubiquinone oxidoreductase subunit core subunit S3, NDUFA13- NADH: ubiquinone oxidoreductase subunit A13, NDUFA3- NADH: ubiquinone oxidoreductase subunit A3), cytochrome c oxidase (COX17), cytochrome c somatic (CYCS) and ubiquinol cytochrome c reductase core protein 1 (UQCRC1). We found lower number of apoptotic cells in blastocysts derived from oocytes collected from prepubertal than those obtained from pubertal donors.ConclusionsDespite decreased expression of genes associated with OXPHOS pathway in blastocysts from prepubertal heifers oocytes, the increased level of ATP12A together with the lower number of apoptotic cells in these blastocysts might support their survival after transfer.

Sperm penetration at the maturing metaphase I stage can trigger oocyte activation in a mouse model

Can spermatozoa penetrate maturing metaphase I (MI) oocytes, and render subsequent development following conventional IVF in a mouse model? ICR mice were used in this study. Metaphase II (MII) cumulus-oocyte complexes (COC) harvested 15 h after injection of human chorionic gonadotrophin (HCG) were used for IVF as the control group (Group 1). In the treatment group (Group 2), maturing MI COC harvested 7 h after HCG injection were used for IVF. Fertilization, pronuclear formation, cleavage, blastocyst formation, DNA methylation status, chromosome number and live birth rates were used to evaluate the developmental dynamics and competency of maturing MI oocytes following conventional IVF. Maturing MI COC were fertilized using conventional IVF, and sperm penetration at MI-telophase I triggered oocyte activation. Most embryos resulting from fertilized MI oocytes developed to blastocyst stage during preimplantation development, albeit a substantial proportion of them were triploids due to the absence of the second meiotic division. Some of the embryos derived from fertilization of maturing oocytes were able to implant and gave rise to full-term development. Maturing MI COC from follicles before ovulation could be used for mouse IVF, and fertilized MI oocytes had high potential for development. Healthy offspring can be generated from maturing MI COC following conventional IVF. MI COC may represent a valuable source of 'usable' biomaterial in assisted reproduction. However, many embryos derived from MI COC via IVF have abnormal chromosome numbers in the mouse model. The implications of these findings for human IVF remain to be investigated.

Human recombinant interleukin-6 improves the morphological quality of cryopreserved in vitro produced bovine blastocysts

This work explored whether a well-characterized recombinant human interleukin-6 (hIL6) protein will influence in vitro produced (IVP) bovine embryo development and survival after cryopreservation. Cumulus oocyte complexes were collected from abattoir derived ovaries, matured for 24 h, and fertilized using pooled semen from Holstein bulls. Embryos were treated with 0, 25, 50, or 100 ng/mL hIL6 on day 5 post-fertilization. An increase in ICM cell numbers was observed in each hIL6 treatment, with the lowest hIL6 treatment having the same magnitude of response as the middle and highest hIL6 concentration. No effects on TE cell numbers were observed. The second study involved cryopreserving (via slow freezing) of hIL6-treated blastocysts, then examining post-thaw blastocyst survival by incubating for 24 h in the absence of hIL6 treatments. Blastocyst re-expansion and hatching rates were unaffected by any of the IL6 treatments, however, increases in both ICM and TE cell numbers were detected at 24 h post-thawing in blastocysts exposed to 100 ng/mL hIL6 but not lower concentrations before freezing. A reduction in the percentage of TUNEL-positive TE cells was observed after thawing in blastocysts exposed to 25, 50 and 100 ng/mL hIL6 before cryopreservation. No treatment-dependent changes in TUNEL-positive ICM cells were observed. In summary, hIL6 supplementation improves ICM cell numbers in bovine blastocysts to a degree that is commensurate with what has been observed when using bovine recombinant IL6. This positive effect of hIL6 on ICM cell numbers is maintained after freezing and thawing, and a novel improvement in post-thaw TE cell numbers occur in hIL6 treated embryos. This positive effect on TE cell numbers is attributed, at least in part, to an hIL6-dependent reduction in TE cell apoptosis.

The impact of cumulus cell viability and pre-culture with the healthy cell mass on brilliant cresyl blue (BCB) staining assessment and meiotic competence of suboptimal porcine oocytes

Objectives of the present study were to investigate the characteristics including glucose-6-phosphate dehydrogenase activity, as determined by Brilliant Cresyl Blue (BCB) staining, of suboptimal porcine oocytes and to enhance the meiotic competence of those through pre-culture with cumulus cell masses (CCMs). Percentage of oocyte-cumulus complexes (OCCs) derived from small follicles (SF; <3 mm in diameter) containing the oocytes that were assessed as BCB-negative (BCB-) was significantly higher than those derived from medium follicles (MF; 3–6 mm in diameter). Degrees of dead cumulus cells were significantly higher in OCCs containing BCB- oocytes, regardless of the origin of OCCs (MF vs. SF), than those containing BCB-positive (BCB+) ones. Exposing OCCs containing BCB+ oocytes to the apoptosis inducer, carbonyl cyanide m-chlorophenylhydrazone, for 20 h significantly induced the transition to BCB- and meiotic progression of exposed OCCs were significantly reduced in both SF and MF derived ones. Transit of BCB- oocytes to BCB+ was induced when OCCs were pre-cultured with CCMs of MF derived OCCs containing BCB+ oocytes for 20 h before IVM. This pre-culture also significantly increased the meiotic competence of BCB- oocytes, particularly in SF derived ones. However, reactive oxygen species levels were significantly higher in BCB+ oocytes as compared with BCB- ones, regardless of pre-culture with CCMs, whereas no significant differences were found in the ATP contents among the treatment groups. In conclusion, the BCB result of oocytes could be regulated by the healthy status and content of surrounding cumulus cells and the meiotic competence of suboptimal BCB- porcine oocytes is improved by pre-culture with healthy CCMs.

Allogenic Follicular Fosterage Technology: Problems, Progress and Potential.

The allogeneic follicular fosterage (AFF) technique transfers cumulus-oocyte complexes (COCs) from pubertal female animals to the dominant follicles of adult female animals for further development, allowing the COCs to further develop in a completely in vivo environment. This article reviews the history of AFF and JIVET and their effects on oocyte and embryo development as well as freezing resistance. Improving the efficiency and reproducibility of AFF technology is crucial to its clinical application. This article discusses factors that affect the success rate of AFF, including differences in specific technical procedures and differences between pubertal and adult follicles. Designing standardized procedures and details to improve the synchronization of donor COCs and recipient follicle maturity and reducing the damage to COCs caused by follicular aspiration may be the direction for improving the success rate of AFF in the future.

Assessment of active translation in cumulus-enclosed and denuded oocytes during standard in vitro maturation and early embryo development.

Which actively translated maternal transcripts are differentially regulated between clinically relevant in vitro and in vivo maturation (IVM) conditions in mouse oocytes and zygotes? Our findings uncovered significant differences in the global transcriptome as well as alterations in the translation of specific transcripts encoding components of energy production, cell cycle regulation, and protein synthesis in oocytes and RNA metabolism in zygotes. Properly regulated translation of stored maternal transcripts is a crucial factor for successful development of oocytes and early embryos, particularly due to the transcriptionally silent phase of meiosis. This is a basic science study utilizing an ICR mouse model, best suited for studying in vivo maturation. In the treatment group, fully grown germinal vesicle oocytes from stimulated ovaries were in vitro matured to the metaphase II (MII) stage either as denuded without gonadotropins (IVM DO), or as cumulus-oocyte complexes (IVM COC) in the presence of 0.075 IU/ml recombinant FSH (rFSH) and 0.075 IU/ml recombinant hCG (rhCG). To account for changes in developmental competence, IVM COC from non-stimulated ovaries (IVM COC-) were included. In vivo matured MII oocytes (IVO) from stimulated ovaries were used as a control after ovulation triggering with rhCG. To simulate standard IVM conditions, we supplemented media with amino acids, vitamins, and bovine serum albumin. Accordingly, in vitro pronuclear zygotes (IMZ) were generated by IVF from IVM DO, and were compared to in vivo pronuclear zygotes (IVZ). All experiments were performed in quadruplicates with samples collected for both polyribosome fractionation and total transcriptome analysis. Samples were collected over three consecutive months. All ICR mice were bred under legal permission for animal experimentation (no. MZE-24154/2021-18134) obtained from the Ministry of Agriculture of the Czech Republic. Actively translated (polyribosome occupied) maternal transcripts were detected in in vitro and in vivo matured mouse oocytes and zygotes by density gradient ultracentrifugation, followed by RNA isolation and high-throughput RNA sequencing. Bioinformatic analysis was performed and subsequent data validation was done by western blotting, radioactive isotope, and mitotracker dye labelling. Gene expression analysis of acquired polysome-derived high-throughput RNA sequencing data revealed significant changes (RPKM ≥ 0.2; P ≤ 0.005) in translation between in vitro and in vivo matured oocytes and respectively produced pronuclear zygotes. Surprisingly, the comparison between IVM DO and IVM COC RNA-seq data of both fractionated and total transcriptome showed very few transcripts with more than a 2-fold difference. Data validation by radioactive isotope labelling revealed a decrease in global translation bof20% in IVM DO and COC samples in comparison to IVO samples. Moreover, IVM conditions compromised oocyte energy metabolism, which was demonstrated by both changes in polysome recruitment of each of 13 mt-protein-coding transcripts as well as by validation using mitotracker red staining. The data discussed in this publication have been deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE241633 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE241633). It is extremely complicated to achieve in vivo consistency in animal model systems such as porcine or bovine. To achieve a high reproducibility of in vivo stimulations, the ICR mouse model was selected. However, careful interpretation of our findings with regard to assisted reproductive techniques has to be made by taking into consideration intra-species differences between the mouse model and humans. Also, the sole effect of the cumulus cells' contribution could not be adequately addressed by comparing IVM COC and IVM DO, because the IVM DO were matured without gonadotropin supplementation. Our findings confirmed the inferiority of standard IVM technology compared with the in vivo approach. It also pointed at compromised biological processes employed in the critical translational regulation of in vitro matured MII oocytes and pronuclear zygotes. By highlighting the importance of proper translational regulation during in vitro oocyte maturation, this study should prompt further clinical investigations in the context of translation. This work was supported by the Czech Grant Agency (22-27301S), Charles University Grant Agency (372621), Ministry of Education, Youth and Sports (EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE), and Institutional Research Concept RVO67985904. No competing interest is declared.

Effect of supplementing epinephrine in maturation media on in-vitro developmental competence of cattle and buffalo oocytes

During in-vitro maturation, the oocyte experiences stressful conditions that likely compromise its development. Epinephrine is a catecholamine that plays a vital role during cellular stress by scavenging free radicals. The hypothesis is that epinephrine addition in maturation media improves the developmental competence of oocytes in cattle and buffalo. The objectives of the experiments were to investigate the effect of epinephrine addition in maturation media on nuclear maturation, developmental competence, and oocyte mRNA abundance of genes related to antioxidants and growth pathways in cattle and buffalo. In experiment 1, cattle oocytes were matured for 24 h in maturation media supplemented with increasing concentrations of epinephrine 0, 0.01, 1.0, and 100 μM. Oocytes were cultured to assess cleavage at 48 h and blastocyst on day 7 of the culture. The cumulus-oocyte complexes (COCs) expansion, nuclear maturation, and oocyte mRNA abundance of genes (SOD1, GPX4, GDF9, CASP9) were evaluated. In experiment 2, buffalo oocytes were matured and assessed for development and mRNA abundance as described for cattle. In addition, the blastomere number was counted in the hatched blastocyst. The data were analyzed using GLIMMIX and MIXED procedures of SAS. Results revealed that the supplementation of epinephrine increased (P ≤ 0.03) the COCs expansion, nuclear maturation, and developmental competence of oocytes in cattle. Interestingly, all the responses were maximized (quadratic effect; P ≤ 0.08) at 1 μM concentrations. The mRNA abundance of genes in cattle oocytes was not affected by the treatment. The experiment in buffalo revealed that epinephrine increased blastocyst formation without affecting COCs expansion, and nuclear maturation. The higher blastocyst was achieved at 0.01 μM concentrations of epinephrine. Interestingly, the addition of epinephrine increased the mRNA abundance of genes related to antioxidant pathways (SOD1, GPX4). Moreover, supplementation of epinephrine increased the blastomere count of the hatched blastocyst in buffalo. In conclusion, epinephrine addition in maturation media benefited oocyte development in cattle and blastocyst yield in buffalo at 1 and 0.01 μM concentrations, respectively. It appears that the addition of epinephrine affected different cellular pathways, COCs expansion, and nuclear maturation in cattle and increased antioxidant genes for buffalo.

Effects of hormone sources on developmental competence of oocytes by ovum pickup in Japanese black cattle

Japanese Black (Wagyu) cattle donors were primed with different protocols and sources of follicle-stimulating hormone (FSH) for successive ovum pickup (OPU) and embryo development after in vitro fertilization (IVF). Following OPU, retrieved cumulus oocyte complexes (COCs) were subjected to IVF, and resulting blastocysts were transferred into recipients to evaluate implantation capability. Experiment 1: The best blastocyst development (45.3 %) and embryo yields (5.0/donor/OPU) were found with oocytes retrieved from donors treated with FSH (STIMUFOL®, Belgium) at a dosage of 150 IU per donor, compared to two others commercial FSH sources. Experiment 2: There were no differences in embryo development or yield with STIMUFOL FSH (total FSH 150 IU/donor) at a priming duration of either 60-h (Regime 1, six FSH injections) or 36-h (Regime 2, four FSH injections). Experiment 3: Compacted COCs required 22–26-h maturation in vitro (IVM) before IVF for optimal blastocyst development (36.1–41.1 %); however, short (18-h) and prolonged (30-h) IVM duration resulted in lower embryonic development. In contrast, expanded COCs resulted in inferior blastocyst development compared to compacted COCs. Immunofluorescence microscopy revealed that the ratio of 89.8 % cumulus compacted COCs were at the germinal vesicle (pachytene) phase while 98.9 % cumulus expanded COCs went through spontaneous meiosis from meiotic metaphase I, anaphase I, telophase I to metaphase II upon OPU retrieval (P<0.05). Pregnancy rates were not different among three FSH sources or different FSH treatments as long as embryos reached the blastocyst stage. Our study found that different sources of FSH used for Wagyu donor priming prior to OPU resulted in differential embryo development potentials, but those embryos that reached out to blastocysts had a competent implantation ability.

Ketoconazole blocks progesterone production without affecting other parameters of cumulus-oocyte complex maturation

Ketoconazole (KTZ) is widely used as a fungicide, but it is also known to target steroid hormone formation which may affect female reproductive health. Our study aims to investigate the effects of KTZ on in vitro matured bovine cumulus-oocyte complexes (COCs), as a model for female reproductive toxicity. Cumulus cells of in vitro maturing COCs produce progesterone and pregnenolone, but exposure to 10−6 M KTZ effectively blocked the synthesis of these hormones. Exposure to lower concentrations of KTZ (i.e. 10−7 M and 10−8 M) had no such effect on steroidogenesis compared to the 0.1 % v/v DMSO vehicle control. Classical parameters of in vitro COC maturation, such as oocyte nuclear maturation to the metaphase II stage and expansion of the cumulus investment, were not affected by any KTZ concentration tested. Apoptosis and necrosis levels were also not altered in cumulus cells or oocytes exposed to KTZ. Moreover, oocytes exposed to KTZ during maturation showed normal cleavage and early embryo development up to day 8 post fertilization; albeit a statistically significant decrease was observed in day 8 blastocysts produced from oocytes exposed to the lowest concentration of 10−8 M KTZ. When unexposed mature oocytes were fertilized, followed by embryo culture for 8 days under KTZ exposure, no adverse effects in embryo cleavage and blastocyst formation were observed. In conclusion, KTZ has no major impact on in vitro bovine oocyte maturation and blastocyst formation in our study, even at concentrations blocking steroidogenesis.

Effect of Ergothineine and Quercetin Additions in to the In Vitro Embriyo Development

Aim: This study aimed to investigate the effects of ergothioneine and quercetin on the in vitro development of bovine embryos Materials and Methods: Cumulus-oocyte complexes (COCs) were collected via ovary aspiration from a local abattoir and cultured in vitro for maturation. After maturation, in vitro fertilization was performed. The pronuclear embryos were divided into three groups: control, 10 μM L-ergothioneine, and 10 μM quercetin supplemented. After the addition of antioxidants to the CR1aa medium, in vitro culture of embryos were performed. The cleavage and morula rates were assessed on days 2 and 5, respectively. Blastocyst formation and quality were assessed on days 7-8. Results: Statistical analysis showed cleavage and morula rates were significantly higher in the ergothioneine group compared to the quercetin and control groups (P&lt;0.05). While no blastocysts formed in the quercetin group, the blastocyst rate reached to 17.96% with ergothioneine supplementation on day 8. Conclusion: In conclusion, supplementation with 10 μM ergothioneine enhanced the in vitro development of bovine oocytes. However, 10 μM quercetin supplementation impaired development, and no blastocyst formation observed. Further studies utilizing different concentrations are warranted to better understand the effects. This study provides insights into modulating oxidative stress during in vitro embryonic production.

Reduced anti-Müllerian hormone action in cumulus-oocyte complexes is beneficial for oocyte maturation without affecting oocyte competence.

Anti-Müllerian hormone (AMH) is a key paracrine/autocrine factor regulating folliculogenesis in the postnatal ovary. As antral follicles mature to the preovulatory stage, AMH production tends to be limited to cumulus cells. Therefore, the present study investigated the role of cumulus cell-derived AMH in supporting maturation and competence of the enclosed oocyte. Cumulus-oocyte complexes (COCs) were isolated from antral follicles of rhesus macaque ovaries for in vitro maturation with or without AMH depletion. Oocyte meiotic status and embryo cleavage after in vitro fertilization were assessed. In vitro maturation with AMH depletion was also performed using COCs from antral follicles of human ovarian tissue. Oocyte maturation and morphology were evaluated. The direct AMH action on mural granulosa cells of the preovulatory follicle was further assessed using human granulosa cells cultured with or without AMH supplementation. More macaque COCs produced metaphase II oocytes with AMH depletion than those of the control culture. However, preimplantation embryonic development after in vitro fertilization was comparable between oocytes derived from COCs cultured with AMH depletion and controls. Oocytes resumed meiosis in human COCs cultured with AMH depletion and exhibited a typical spindle structure. The confluency and cell number decreased in granulosa cells cultured with AMH supplementation relative to the control culture. AMH treatment did not induce cell death in cultured human granulosa cells. Data suggest that reduced AMH action in COCs could be beneficial for oocyte maturation. Cumulus cell-derived AMH is not essential for supporting oocyte competence or mural granulosa cell viability.

Estrogen influences the transzonal projection assembly of cumulus-oocyte complexes through G protein-coupled estrogen receptor during goat follicle development.

Estrogen is an important hormone that plays a role in regulating follicle development and oocyte maturation. Transzonal projections (TZPs) act as communication bridges between follicle somatic cells and oocytes, and their dynamic changes are critical for oocyte development and maturation. However, the roles and mechanisms of estrogen in regulating TZPs during follicular development are not yet understood. We found that the proportion of oocytes spontaneously resuming meiosis increases as the follicle grows, which is accompanied by rising estrogen levels in follicles and decreasing TZPs in cumulus-oocyte complex. To further explore the effect of elevated estrogen levels on TZP assembly, additional estrogen was added to the culture system. The increased estrogen level significantly decreased the mRNA and protein expression levels of TZP assembly-related genes. Subsequent research revealed that TZP regulation by estrogen was mediated by the membrane receptor GPER and downstream ERK1/2 signaling pathway. In summary, our study suggests that estrogen may regulate goat oocyte meiosis arrest by decreasing TZP numbers via estrogen-mediated GPER activation during follicle development.