Exploring the Potential of Metaphase I Oocytes Unresponsive to Rescue IVM: Fertilization, Embryo Development, and Pregnancy Outcomes

doi:10.21203/rs.3.rs-8343259/v1

Backround: The aim of thisprospectivecohortstudywastoevaluatethedevelopmentalpotential of metaphase I (MI) oocytes that failed to reach maturation following rescue in vitro maturation (IVM).

Method: ICSI was performed to these oocytes and they were subsequentlyplaced in the calcium ionophore-containing medium for 20 minutes, washed in culture medium and incubated until fertilization assessment.In total of 263 patients and 276 ICSI cycles are included.Of these, 28 patients had onlyimmature oocytes that did not respond to IVM.

Results: The mean age of the study population was 36.4±4 and the primary indication for treatment was low ovarian reserve, accounting for 39.3% of cases.The average number of retrieved oocytes was 6.7, the average count of MII oocytes was 4, while the average count of MI oocytes was 2. Fertilization of MI oocytes occurred in 17 out of 28 patients(60.7%).Among the fertilized zygotes, 29.4% were classified as Z2PN, while 52.9% were identified as Z3PN.Amoung 8 embryos that reached day 4; 5 were fresh trasnferred. One patient had ß HCG positivity. 3 embryos are frozen and thawed transferred; one patient had positive ß HCG. The clinical pregnancy rate was determined to be 25% (2/8). Only one pregnancy ended in live birth (live birth rate 12.5%).

Conclusion: This study demonstrated the developmental potential of MI oocytes that failed to mature after rescue IVM. Utilizing these MI oocytes could increase the number of transferable embryos, enhance the efficiency of ICSI cycles, and improve pregnancy rates, as each embryo holds clinical significance.

Immature oocytes

ICSI

in vitro maturation (IVM)

In assisted reproductive techniques (ART), only 5% of oocytes obtained through ovarian stimulation result in live births [1].The maturity of the oocyte plays a critical role in the success of IVF treatments. For optimal fertilization and embryo development, microinjection is typically performed on metaphase II (MII) oocytes. However, studies indicate that a substantial proportion of retrieved oocytes, approximately 15–25%, are immature at the time of retrieval [2, 3]. Some authors highlighted that immature oocytes can be subjected to in vitro maturation protocols to achieve MII status (Ahmad et al.). It is also demonstrated that MII oocytes derived from initially immature oocytes retain the capacity to undergo normal fertilization and early embryonic development, supporting their potential use in clinical IVF practice (Shani et al).

Immature oocytes are classified into three stages of nuclear maturation: prophase I (PI), metaphase I (MI), and, less commonly, telophase I (TI). Oocytes arrested in PI, commonly referred to as germinal vesicle (GV) oocytes, have a large nucleus centrally located within the cytoplasm. The GV stage represents the earliest maturation stage, and GV oocytes are almost always discarded during IVF-ICSI cycles. MI oocytes have progressed further through meiosis and are closer to maturity but require the extrusion of a polar body to transition into MII—the highest maturity grade an oocyte can achieve. TI oocytes, which represent a very brief transitional stage characterized by th eextrusion of the first polar body, are rarely distinguished in clinical practice and are typically treated as MI or early MII oocytes during ICSI.

Rescue in vitro maturation (IVM) is a technique used in IVF treatment where immature oocytes, primarily MI oocytes, are cultured to achieve maturity for ICSI. Although in vitro matured oocytes typically yield lower outcomes compared to in vivo matured oocytes [4], rescue IVM is an important alternative for specific patient groups, such as those with polycystic ovary syndrome (PCOS), unsynchronized follicular cohorts, or poor ovarian response [5]. However, many MI oocytes do not respond to the IVM process, failing to extrude a polar body, complete nuclear maturation, or transform into MII oocytes.

ART clinics strive to optimize the number of embryos available for fertilization and pregnancy. Despite various culture techniques, not all MI oocytes develop into MII oocytes. But should MI oocytes always be discarded? This study investigates the clinical use of MI oocytes for ICSI, evaluating their developmental competence when they fail to respond to rescue ivm procedures.

Study description

This prospectivecohortstudywasconducted at Istanbul University, Istanbul Faculty of Medicine, Department of Obstetrics and Gynecology, IVF Unit. Ethical approval was obtained from the Faculty’s Ethics Committee (approval no: E-54073746-108.99-2511084). Written informed consent was obtained from all participating couples.

Clinical and laboratory data of patients who underwent IVF-ICSI treatment at the unit between October 2023 and April 2024 were prospectively recorded during the treatment process and subsequently analyzed for this study. In accordance with national regulations, all IVF/ICSI cycles were performed using autologous oocytes. Patients who met the following inclusion and exclusion criteria were included in the analysis.

Inclusion Criteria

IVF cycles using autologous oocytes,
Women aged 18–40 years,
Body mass index (BMI) between 18.5 and 30, calculated as weight (kg)/height² (m²),
At least one MI oocyte resistant to rescue IVM and used for intracytoplasmic sperm injection (ICSI),
ICSI cycles resulting in at least one grade 1 embryo derived from either in vivo or in vitro matured MII oocytes. In these cases, even if a high-quality embryo was developed from an MI oocyte, the embryo derived from an MII oocyte was prioritized for transfer.

Exclusion Criteria:

Oncofertility patients,
Oocyte freezing cycles,
Fertility preservation cycles,
Women over 40 years of age,
BMI < 18.5 or > 30,
Cycles in which all retrieved oocytes were MII,
Cycles with complete rescue IVM success, where all MI oocytes matured,
Germinal vesicle (GV) oocytes.

Stimulation Protocol

All patients underwent the GnRH antagonist protocol. Controlled ovarian hyperstimulation (COH) was initiated on the third day of the menstrual cycle with recombinant FSH (Gonal-F, EMD Serono, MA, USA) at a daily dose of 75–300 IU. Pituitary suppression was achieved using cetrorelix 0.25 mg/day (Cetrotide, Serono, Geneva, Switzerland), which was started once at least one follicle reached a diameter of 14 mm. Final oocyte maturation was triggered with 6500 IU of hCG (Ovitrelle, Merck KGaA, Darmstadt, Germany) when at least two follicles had reached a size of 17 mm or larger.

Oocyte pick up (OPU)

Oocyte aspiration was performed 35–36 hours after hCG administration using a Labotect device (Model 4014, Germany) and double-lumen OPU needles (Swemed 14105, Sweden). Each follicle was meticoulously aspirated into sterile tubes (Falcon 2003, USA/France) containing follicular fluid prepared with GMOPS solution and GMOPS + HSA medium (Vitrolife, Sweden, EU). The aspirated contents were examined under a stereomicroscope in the embryology laboratory (Olympus SZH10, Japan).

Oocytes were denuded approximately 3 hours after oocyte retrieval, and subsequently the cumulus-oocyte complex (COC) was evaluated under an inverted microscope to assess the maturation stage of the oocytes. Oocytes were classified into the following stages: metaphase II (MII), metaphase I (MI), germinal vesicle (GV), and germinal vesicle-intact (GIV). GV (germinal vesicle) oocytes represent the earliest stage of nuclear maturation, characterized by a visible nucleus within the cytoplasm and absence of meiotic progression. Mature metaphase II (MII) oocytes exhibiting cytoplasmic or extracytoplasmic abnormalities, such as granular cytoplasm or vacuoles, were classified as GIV oocytes [6].

Rescue IVM protocol

During the study period, rescue in vitro maturation (IVM) was performed for all cycles involving MI oocytes. Oocytes retrieved 36 hours after the hCG trigger were initially incubated for approximately 3 hours in an incubator with 7% CO₂ and 5% O₂. Denuding (the cumulus cells surrounding the oocytes are removed using hyaluronidase enzyme and mechanical methods) occurred after 3 hours of incubation. Immature MI oocytes were reassessed at 40 hours. Oocytes remaining at the MI stage were incubated in Life Global Total for Fertilization Medium (Cooper Surgical, Denmark) under the same atmospheric conditions (7% CO₂ and 5% O₂). Medium for use after OPU and oocyte denudation is a single-stage culture medium containing essential ions, energy substrates (glucose, pyruvate, lactate), amino acids, vitamins, and a specific protein source. Optimized to support oocyte metabolism and promote maturation, it provides a stable environment for short-term culture of immature oocytes prior to ICSI without the need for sequential medium changes.Four hours after denudation, intracytoplasmic sperm injection (ICSI) was performed on the remaining immature MI oocytes.

ICSI procedure protocol

After denuding, the cleared oocytes were evaluated for maturation under an inverted microscope. MII (metaphase II) oocytes underwent microinjection (ICSI) at hour 40 using sperm from the patients' partners under an inverted microscope. Immature (MI) oocytes underwent ICSI after an additional 4 hours of incubation.

In cases with maturation defects, artificial oocyte activation (AOA) using calcium ionophore is hypothesized to enhance cytoplasmic maturation by inducing calcium oscillations, which are essential for meiotic resumption, oocyte activation, and early embryonic development, even when nuclear maturation is incomplete. In this study, for MI oocytes, chemical activation was performed using calcium ionophore (GM508 Cult-Active-Calcium Ionophore, Germany) prepared in 30 µl droplets. The droplets were pre-incubated for at least 4 hours at 37°C in an environment with 7.2–7.4 pH and 5–7% CO2. MI oocytes that underwent ICSI were placed in the calcium ionophore-containing medium for 20 minutes. While the standard exposure time for CultActive has often been reported as 15 minutes [7], previous studies using calcimycin have shown the safety of 20 minutes or longer incubation [8]. In our clinic, a 20-minute exposure was chosen as, according to our personal clinical experience, it yielded higher fertilization rates compared with shorter durations. Afterward, the oocytes were washed in a culture medium free of HEPES and MOPS, transferred to IVF culture medium, and incubated until fertilization assessment (Vitrolife, Sweden, EU).

Assessment of Meiotic Spindle by Polarized Light Microscopy

In addition to routine evaluation of nuclear maturation, polarized light microscopy was used to assess the presence, visibility, and localization of the meiotic spindle in MI oocytes that failed to mature after rescue IVM. All oocytes were examined using a PolScope system integrated into an inverted microscope (Nikon Eclipse Ti-U, Tokyo, Japan). Oocytes were placed in 20–30 µl microdroplets of culture medium under mineral oil and maintained at 37°C during imaging. Each oocyte was evaluated within 5–10 minutes to minimize thermal and pH stress.Spindle visualization was performed using fixed exposure, contrast and birefringence settings for all samples. A spindle was recorded as “visible” when a birefringent, barrel-shaped microtubule structure with a clear long axis could be identified.

MI oocytes were categorized as follows:

MI–No Spindle: No birefringent structure was detected and no polar body was present.

MI–Spindle Positive (Transition MI): A located meiotic spindle was detected despite the absence of the first polar body.

Spindle visibility rates and descriptive morphology of MI oocytes were included in the analysis to determine whether MI oocytes failing IVM showed signs of ongoing nuclear progression toward MII.

Fertilization and Embryo Evaluation

Fertilization was assessed approximately 20 hours after ICSI. Normal fertilization was confirmed by the presence of two polar bodies and two pronuclei (2PN). Zygotes were graded as follows [9]:

Zygote I (ZI)

Very good

Zygote II (ZII): Good
Zygote III (ZIII): Moderate
Zygote IV (ZIV): Poor

For embryos, grading was performed on days 2, 3, and 4 based on their developmental progress. Embryo quality was categorized as:

• Good (GI)

• Moderate (GII)

• Poor (GIII)

Embryo Transfer

Embryo development was monitored daily, starting with fertilization and cleavage observations from day 1. Selected embryos were transferred, and pregnancy was evaluated approximately 12 days later by measuring beta-hCG levels in the blood. Pregnancy monitoring was initiated for patients with positive beta-hCG results.All embryo transfers were performed under ultrasound guidance by the same infertility and reproductive endocrinology specialist, who is also an IVF expert. Luteal phase support was administered using intramuscular progesterone in oil and vaginal progesterone suppositories. The decision to freeze all embryos was made based on individual patient characteristics, including endometrial status, hormone levels, and the risk of developing ovarian hyperstimulation syndrome (OHSS).

Assessment Measures

Reproductive outcomes were defined as follows:

Pregnancy: A positive beta-HCG level in serum measured 14 days after embryo transfer.
Clinical Pregnancy: The presence of one or more intrauterine sacs visible on ultrasound at 7 weeks of gestation.
Ongoing Pregnancy: A pregnancy confirmed by ultrasound to have progressed beyond the 12th gestational week.

Statistical analysis

SPSS version 27 was used for statistical analysis. The Shapiro-Wilk test was applied to assess the conformity of the data to a normal distribution. Descriptive statistics were used to evaluate both demographic data and fertilization and pregnancy outcomes. Continuous variables were reported as mean ± standard deviation (SD) along with minimum and maximum values. Categorical variables were presented as counts (n) and percentages (%).

During the study period, 263 patients underwent 276 ICSI cycles in our clinic. Of these, 28 patients met the inclusion and exclusion criteria and were included in the study. The mean age of the study group was 36.4 ± 4 years (range 27–44), and the mean age of their partners was 38.5 ± 3.9 years (range 31–47). The primary indication for treatment was low ovarian reserve, accounting for 39.3% of cases.

The average infertility duration was 4 years. The mean anti-Mullerian hormone (AMH) level was 2.1 ± 1.9 and the average number of retrieved oocytes was 6.7 ± 4.7. Of these, the average count of MII oocytes was 4, while the average count of MI oocytes was 2. The demographic characteristics of the participants are detailed in Table 1.

Polarized light microscopy was successfully performed on MI oocytes resistant to rescue IVM. Two spindle patterns were identified. A subset of MI oocytes displayed a located metaphase spindle despite the absence of the first polar body (MI–Spindle Positive), indicating ongoing nuclear maturation without completed cytokinesis. In contrast, classic MI oocytes showed no birefringent structure (MI–No Spindle). These findings suggest that a proportion of MI oocytes failing short-term IVM may nevertheless enter late MI/transition stages, potentially retaining partial meiotic competence. Representative polarized images of spindle-positive and spindle-negative MI oocytes are provided in Figure 1.

MI oocytes were activated using calcium ionophore, resulting in a fertilization rate of 55.5%. Fertilization of MI oocytes occurred in 17 out of 28 patients (60.7%). Among the fertilized zygotes, 29.4% were classified as Z2PN, while 52.9% were identified as Z3PN (Table 2).

On the second day, 11 embryos (64.7%) had developed, with 41.2% of them graded as Grade 1. All these embryos progressed to Day 3. Two Grade 1 embryos on Day 2 developed into Grade 2 by Day 3, while one embryo progressed to Grade 3. Three embryos arrested, and 8 embryos (47.1%) advanced to Day 4.

Of these 8 embryos, 3 were frozen as part of freeze-all cycles, and 5 out of 14 embryos (35.7%) were fresh transferred. One of the five fresh embryo transfers ended in pregnancy. The implantation pregnancy rate was determined to be 20% based on the number of fresh embryos transferred (Table 2, Diagram 1). This pregnancy resulted in healthy live birth. Amoung remaining 3 frozen embryos; all were thawed and transferred (single embryo transfer). Two patients did not achieve pregnancy and one patient experienced biochemical pregnancy. Therefore all the 8 embryos were trasnferred and one biochemical pregnancy and one pregnancy with term and healthy birth occured (implantation rate 25%, live birth rate 12.5).

This study explored the developmental potential of MI oocytes that did not respond to rescue IVM. The findings indicate that, despite their well-known limitations compared to in vivo matured MII oocytes, immature MI oocytes can still undergo fertilization, embryo development, and even result in pregnancy. These results highlight the possibility that MI oocytes, which are usually discarded in routine IVF practice, may represent an additional resource for patients undergoing assisted reproduction.

A significant and unresolved issue in IVF-ICSI cycles is immature oocytes. In standard practice, insemination is performed exclusively on MII oocytes. While rates vary slightly between studies, approximately 4% of collected oocytes are in metaphase I (MI) and 11% are at the germinal vesicle (GV) stage [10, 11, 12]. Other studies have reported that around 20% of oocytes are immature [13]. Even though the clinical efficacy and safety of in vitro maturation in stimulated cycles in a subject of ongoing debate, rescue IVM is routinely applied to all MI oocytes, regardless of the patient’s MII oocyte count, as part of a strategy to optimize cycle outcomes in our INF Unit, because each mature oocyte contributes to cumulative pregnancy and live birth rates [14]. Additionally, a higher proportion of immature oocytes within the total yield is associated with reduced pregnancy potential of mature sibling MII oocytes [8]. For this reason, every MI oocyte is considered valuable. If MI oocytes extrude the first polar body within a few hours, they are rescued, matured in vitro, and subsequently inseminated. Approximately 60% of immature oocytes progress to the MII stage [14]. However, when IVM fails and MI oocytes do not mature, they are typically discarded in most IVF units.

In this study, MI oocytes that failed to mature following rescue IVM demonstrated measurable developmental potential, with clinically relevant fertilization and embryo formation rates. Polarized light microscopy revealed that MI oocytes are not a uniform population. In a subset of MI oocytes, a well-defined metaphase spindle was observed despite the absence of the first polar body, suggesting that these oocytes had initiated nuclear maturation and may represent a “late MI/MI–MII transitional” stage. In contrast, spindle-negative MI oocytes reflected an earlier phase of meiosis. This biological variability aligns with our clinical findings, in which MI oocytes contributed to embryo development and, in some cases, resulted in pregnancy. Spindle-positive MI oocytes may possess greater developmental competence due to more advanced nuclear organization, whereas spindle-negative oocytes likely have limited maturation progression. Thus, polarized light imaging may serve as a useful, non-invasive tool to discriminate the developmental potential of MI oocytes that fail to respond to rescue IVM, rather than discarding them uniformly. Overall, our findings indicate that a proportion of MI oocytes are not irreversibly immature and—with appropriate laboratory support—can yield clinically meaningful embryos. The pregnancy rate for MI oocytes was 25%, and live birth rate 12.5%, a promising result that highlights the potential of utilizing these oocytes in IVF treatments.

Another important consideration is fertility preservation through gamete vitrification. Ideally, vitrification should be performed on mature oocytes at the metaphase II (MII) stage, as this provides the best chance of future pregnancy. To maximize success, a large number of oocytes should be cryopreserved. Unfortunately, the time required for controlled ovarian hyperstimulation (COH) and oocyte retrieval often delays cancer treatment, leaving infertility specialists with limited opportunities to perform multiple cycles for cancer patients. As a result, freezing too few oocytes significantly reduces the likelihood of achieving a future pregnancy.In these cases, cryopreserving both MII and immature oocytes could be a viable option [15]. This study demonstrates that MI oocytes have the potential to result in pregnancy, supporting the notion that they should be frozen alongside their sibling MII oocytes.

There is also another perspective to consider. When a cancer patient has recovered and seeks pregnancy using her cryopreserved oocytes, IVF specialists thaw the oocytes. In situations where no mature oocytes survive the thawing process, MI oocytes can become a valuable resource. These oocytes can either be matured in vitro (IVM) and used once they reach full maturity or utilized as they are, as shown in this study. This highlights the importance of preserving MI oocytes as an additional option for fertility preservation.

As expected, MI oocytes exhibit compromised developmental competence. Mature oocytes play a critical role in achieving a successful pregnancy, and the use of immature oocytes is associated with poorer clinical outcomes in IVF/ICSI cycles. Even MII oocytes obtained after IVM show lower fertilization, blastulation, and pregnancy rates [16, 17, 18]. In vivo matured oocytes remain the optimal choice. For patients with a history of a low proportion of mature oocytes, several strategies can be employed to increase the number of in vivo matured oocytes. These include adding LH to COH protocols, using a double trigger with GnRH agonist and hCG, extending the interval between hCG administration and oocyte retrieval, modifying the IVF protocol, or changing the FSH type (recombinant or hMG). However, this topic is beyond the scope of this paper.

Rescue IVM has been described with different approaches in the literature, including both prolonged culture of immature oocytes and the direct use of MI oocytes after cumulus removal. In our study, the prolonged culture method was applied, which remains a subject of debate regarding its efficiency compared with direct MI injection. Nevertheless, our findings underline the critical role of assisted oocyte activation in supporting fertilization and embryo development from immature oocytes

The major strength of this study lies in its novel perspective on MI oocytes. Utilizing MI oocytes that do not respond to rescue IVM is an innovative approach in embryology clinics and may contribute to increased overall pregnancy rates. However, this study also has several limitations.

The first limitation is the small sample size, which restricts the generalizability of the findings. Further studies with larger sample sizes are necessary to validate these results.The second limitation is a selection bias in the study population. Only couples who did not have any embryos derived from in vivo or in vitro matured MII oocytes received an MI-derived embryo. This indicates that the investigated population had some degree of oocyte maturation defect or a low oocyte quality profile, limiting the universality of the findings. One other limitation is that none of the embryo transfers in this study were day 5 blastocyst transfers, and no preimplantation genetic diagnosis (PGD) was performed. As a result, this study cannot provide data on blastulation rates (the percentage of blastocysts obtained) or euploidy rates. These aspects should be addressed in future research. In addition, the developmental competence and safety of MI oocytes that fail to reach MII after short-term culture remain uncertain. The potential risk of transmitting aneuploidies or epigenetic alterations should be carefully considered before suggesting any clinical application. Therefore, the present study does not advocate immediate clinical use of such oocytes but rather highlights their potential and the need for further prospective research. Larger studies with structured designs, appropriate control groups, and detailed chromosomal and epigenetic analyses are warranted before clinical translation can be considered.

This study demonstrated the developmental potential of MI oocytes that failed to mature after rescue IVM. Utilizing these MI oocytes could increase the number of transferable embryos, enhance the efficiency of ICSI cycles, and improve pregnancy rates, as each embryo holds clinical significance.Moreover, polarized light microscopy demonstrated that some MI oocytes exhibit a centrally positioned meiotic spindle even without polar body extrusion, indicating progression toward nuclear maturation. These observations suggest that MI oocytes are not a homogeneous group and that a subset may possess residual developmental competence. Thus, spindle assessment may represent a valuable non-invasive adjunct for identifying MI oocytes with clinical potential, especially in cycles with a limited number of mature oocytes.

Nevertheless, it should be noted that the presentstudydid not include a control group, which limits the strength of the conclusions. While the primary aim was to describe the developmental potential of MI oocytes that failed rescue IVM, and not to compare them with in vivo matured MII oocytes, the absence of such a comparison restricts the generalizability of the findings. Future studies should therefore incorporate appropriate control groups and larger sample sizes in order to validate and expand upon these preliminary observations and to better define the potential clinical utility of immature oocytes in assisted reproduction.

Funding Statement:There is no financial support.

Funding

None.

Disclosure Statement:The authors have no conflicts of interest.

Attestation Statement:

• The subjects in this trial have not concomitantly been involved in other randomized trials

• Data regarding any of the subjects in the study has not been previously published.

• Data will be made available to the editors of the journal for review or query upon request.

Data Sharing Statement:Raw data can be shared and will be available upon request.

Ethical approval: Istanbul University, Istanbul Faculty of Medicine Institutional Review Board approved this study.(Protocol Number: 2024 / 1183).

Capsule: MI oocytes that failed to mature after rescue IVM can increase the number of transferable embryos, enhance the efficiency of ICSI cycles, and improve pregnancy rates.

Author contributions

AA designed the study and revised the manuscript. BKB,CC provided expert opinions and drafted the manuscript. ÖD,CA assisted with data collection, statistical analyses, and editing. All authors contributed to the manuscript and approved the submitted version. Artificial intelligence has not been used.

Conflict of interest

The authors declare no potential conflicts of interest.

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Table 1: Baseline demographic data, hormone levels, and reproductive characteristics of the study population. Data are presented as mean ± standard deviation (range: min–max).

	n=28
Indication	Low Ovarian Reserve (LOR) – 11 (%39.3) Male Factor – 6 (%21.4) Endometriosis– 3 (%10.7) Tubal Factor– 3 (%10.7) Unexplained– 3 (%10.7) Male Factor + LOR – 2 (%7.1)
Age (Patient)	36.4 ± 4 (27 – 44)
Age (Partner)	38.5 ± 3.9 (31 – 47)
Body Mass Index	26 (19 – 39)
Infertility period (year)	4 (0.25 – 14)
Antral FollicleCount	6 (1 – 13)
Anti-Mullerian Hormone	2.1 ± 1.9 (0.2 – 9.3)
Follicle Stimulating Hormone	7.2 ± 2.9 (0.3 – 13.7)
Luteinizing Hormone	6.1 ± 3 (0.3 – 14)
Estradiol	56.9 ± 25.2 (16 – 153)
Number of oocytes	6.7 ± 4.7 (1 – 21)
MII	4 (1 – 18)
MI	2 (1 – 5)
GV	1 (0 – 4)
GIV	2 (0 – 7)

Table 2: Outcomes of ICSI to MI oocytes resisted to rescue IVM.

Fertilization rate(%)	55.5 ± 48.4 (0 – 100) 14- % 100 1- % 25 1- % 50 1- % 80
MI Fertilization (+) number of patients	17 / 28 (% 60.7)
Pronucleus Grade 2PN-ZI 2PN-ZII 2PN-ZIII 2PN-ZIV	- 5 / 17 (% 29.4) 9 / 17 (% 52.9) 3 / 17 (% 17.6)
Number of Embryos Reaching the Second Day	11 / 17 (% 64.7)
Embryo Grade Reaching Day Two D2GI D2GII D2GIII	7 / 17 (% 41.2) 3 / 17 (% 17.6) 1 / 17 (% 5.9)
Number of Embryos Reaching the Third Day	11 / 17 (% 64.7)
Embryo Grade Reaching Day Three D3GI D3GII D3GIII	4 / 17 (% 23.5) 5 / 17 (% 29.4) 2 / 17 (% 11.8)
Number of Embryos Reaching Day Four	8 / 17 (% 47.1)
Number of MI Fresh Embryo Transfers	5 / 14 (% 35.7) (3 Embryos were Frozen due to Freeze All cycles)
Transferred Embryo Grade	Grade 1 (% 100 – 5 / 5)
Pregnancy Rate (According to the number of fertilized oocytes)	1 – Biochemical(% 7.1) 1 – Clinical pregnancy(% 7.1) 3 – Negative (% 21.4)
Pregnancy Rate (Per embryo transferred)	1 – Biochemical (% 20) 1 – Clinical pregnancy(% 20) 3 – Negative (% 60)
Number of MI Frozen Embryo Transfers	3/3 (%100)
Embryo grades of frozen embryo transfers	Grade 1 (% 100 – 3 / 3)
Pregnancy Rate (Per frozen embryo transferred)	0 – Biochemical 0– Clinical pregnancy 3 – Negative (% 100)

Diagram 1 is available in the supplementary files section.

No competing interests reported.

Diagram1.png

Exploring the Potential of Metaphase I Oocytes Unresponsive to Rescue IVM: Fertilization, Embryo Development, and Pregnancy Outcomes

Status:

Version 1

Abstract

Figures

INTRODUCTION

MATERIALS AND METHODS

Study description

Inclusion Criteria

Exclusion Criteria:

Stimulation Protocol

Oocyte pick up (OPU)

Rescue IVM protocol

ICSI procedure protocol

Assessment of Meiotic Spindle by Polarized Light Microscopy

Fertilization and Embryo Evaluation

• Good (GI)

• Moderate (GII)

• Poor (GIII)

Assessment Measures

Statistical analysis

RESULTS

DISCUSSION

CONCLUSION

Declarations

References

Tables

Diagram 1

Additional Declarations

Supplementary Files

Status:

Version 1