Human embryos derived from first polar body nuclear transfer exhibit comparatively abnormal morphokinetics during development

OBJECTIVE

Reconstructed oocytes after polar body genome transfer constitute a potential therapeutic option for patients with a history of embryo fragmentation and advanced maternal age. However, the rescue of genetic material from the first polar body (PB1) through introduction into the donor cytoplasm is not yet ready for clinical application.

METHODS

Eighty-five oocytes were obtained following in vitro maturation (IVM) and divided into two groups: PB1 nuclear transfer (PB1NT; n=54) and control (n=31). Following enucleation and PB1 genomic transfer, PB1 fusion was assessed. Subsequently, all fused oocytes underwent intracytoplasmic sperm injection (ICSI) and were cultured in an incubator under a time-lapse monitoring system to evaluate fertilization, embryonic morphokinetic parameters, and cleavage patterns.

RESULTS

Following enucleation and fusion, 77.14% of oocytes survived, and 92.59% of polar bodies (PBs) fused. However, the normal fertilization rate was lower in the PB1NT group than in the control group (56.41% vs. 92%, p=0.002). No significant differences were observed in embryo kinetics between the groups, but a significant difference was detected in embryo developmental arrest after the four-cell stage, along with abnormal cleavage division in the PB1NT group. This was followed by significant between-group differences in the implantation potential rate and euploidy status. Most embryos in the PB1NT group had at least one abnormal cleavage division (93.3%, p=0.001).

CONCLUSION

Fresh PB1NT oocytes successfully produced normal zygotes following PB fusion and ICSI in IVM oocytes. However, this was accompanied by low efficiency in developing into cleavage embryos, along with an increase in abnormal cleavage patterns.

High efficiency of homemade culture medium supplemented with GDF9-β in human oocytes for rescue in vitro maturation

Objective

Optimizing culture media for the incubation of immature oocytes is a vital strategy to increase the oocyte maturation rate during in vitro maturation (IVM) programs. This study evaluated the IVM and fertilization rates of human germinal vesicle (GV) and metaphase I (MI) oocytes using two different maturation media (commercial and homemade) with or without growth differentiation factor 9-β (GDF9-β). supplementation.

Methods

Immature oocytes from intracytoplasmic sperm injection (ICSI) cycles were collected and assigned to one of two IVM culture media (commercial or homemade; cleavage-stage base). After maturation, MII oocytes were examined under an inverted microscope for the presence of the polar body, zona pellucida (ZP) birefringence, and meiotic spindle (MS) visualization after maturation in four conditions (commercial or homemade medium, with or without GDF9-β. ICSI was done for matured oocytes, and fertilization was confirmed by the visualization of two distinct pronuclei and two polar bodies.

Results

No significant differences were found between the two culture media in terms of the time and rate of oocyte maturation or the rate of fertilization (p>0.05). Growth factor supplementation increased the 24-hour maturation rate for both GV and MI oocytes only in homemade medium. The maturation rate after 24 hours was higher for MI oocytes (p<0.05). Similar results were observed for MS visualization and ZP structure in both types of media (p>0.05).

Conclusion

Higher rates of oocyte maturation and fertilization were observed after application of homemade medium supplemented with GDF9-β. Therefore, this combination may be recommended as an alternative for clinical IVM programs.

Analysis of maturation dynamics and developmental competence of in vitro matured oocytes under time-lapse monitoring

BACKGROUND

To improve the developmental competence of in vitro cultured oocytes, extensive literature focused on maturation rate improvement with different additives in culture medium, while studies investigating the maturation dynamics of oocytes during in vitro maturation (IVM) and the influencing factors on oocyte viability are scarce.

METHODS

The study involved a retrospective observation by time-lapse monitoring of the IVM process of 157 donated GV oocytes from 59 infertile couples receiving ICSI in 2019, in Tongji Hospital, Wuhan, China. The GV oocytes derived from controlled ovarian hyperstimulation (COH) cycles underwent rescue IVM (R-IVM), and the maturation dynamics, including GVBD time (GV-MI), time from GVBD to maturation (MI-MII), maturation time (GV-MII), and MII arrest duration (MII-ICSI), were recorded by time-lapse monitoring. The matured oocytes were inseminated at different MII arrest points and subsequent embryo developments were assessed. The effects of baseline clinical characteristics, oocyte diameters, and maturation dynamics on the developmental competence of the oocytes were also analyzed.

RESULTS

Totally, 157 GV oocytes were collected. GVBD happened in 111 oocytes, with a median GV-MI duration of 3.7 h. The median MI-MII duration was 15.6 h and the median GV-MII duration was 19.5 h. The maturation rate reached 56.7% at 24 h and 66.9% at 48 h, and the clinical factors, including patient age, FSH level, AMH level, ovarian stimulation protocol, and serum estradiol and progesterone levels on hCG trigger day, showed no effects on the 24-h maturation rate. The normal fertilization rate of oocytes resuming meiosis within 8 h and matured within 24 h was significantly higher than that of oocytes resuming meiosis after 8 h and matured after 24 h. Furthermore, among those oocytes matured within 24 h, the high-quality embryo formation rate of oocytes resuming meiosis within 4.5 h and matured within 19 h was significantly higher. All stated time was measured from the start point of IVM. Additionally, for oocytes from patients with serum progesterone levels less than 1 ng/ml on hCG trigger day, the high-quality embryo formation rate was significantly increased.

CONCLUSION

R-IVM technology could increase the available embryos for patients in routine COH cycles, but excessive culture beyond 24 h is not recommended. GV-MI duration of the oocyte, recorded by time-lapse system, and serum progesterone levels of patients on hCG trigger day can significantly affect the developmental potential of the IVM oocytes.

Morphokinetic evaluation of embryos generated from vitrified oocytes maintaining the meiotic spindle

Vitrification is a technique for preservation of human oocytes. There is still a lack of basic research about the possible effects of vitrification on subsequent embryos following oocyte vitrification. The purpose of this study was to evaluate the embryo morphokinetic parameters formed after fertilization of vitrified-warmed oocytes, where an intact meiotic spindle (MS) was observed pre- and post-cryopreservation. Matured oocytes after in vitro maturation were collected and MS evaluation was performed. The oocytes with MS were divided into two groups: fresh and post vitrification. After intra-cytoplasmic sperm injection, the oocytes were cultured in time lapse monitoring (TLM) and time of second polar body extrusion (SPBE), pronuclei appearance (tPNA), pronuclei fading (tPNF), formation of two to eight cells (t2 to t8), and irregular cleavage events [direct cleavage (DC), reverse cleavage (RC)] and vacuolation were assessed. The fertilization rate was not significantly different between the groups, although the rate of abnormal fertilization was higher in vitrification group compared with fresh group (23.5% VS 7.7%). Analysis of the TLM showed a significant delay in time points, including SPBE, tPNA, tPNF, t 2-cells cleavage in vitrification group (p = 0.02, p = 0.00, p = 0.002, P = 0.00, P = 0.01, respectively). In addition, t3 and t4 time points tended to be delayed in vitrification group (p = 0.05). Moreover, the higher level of DC, RC and vacuolation were noticed in the vitrification group (P˂0.05). In conclusion, despite MS maintenance after warming, TLM evaluation showed both a delay and abnormal cleavage patterns in generated embryos.

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.

Efficacy of the in vitro splitting of human preimplantation embryos from ART programs

Background/aim

The aim of this study was to evaluate the efficiency of in vitro embryo splitting (IES) procedures. We also assessed the quality of the blastocysts developed from embryos obtained from different sources.

Materials and methods

Good quality embryos at 6–8-cell stages were categorized according to their fertilization sources: 1) frozen-warmed donated embryos, 2) chromosomally abnormal embryos, 3) parthenogenetic embryos, and 4) embryos derived from fertilization of in vitro matured oocytes (rescue IVM). After IES, splitting and developmental efficiency was assessed. Furthermore, the quality of the developed blastocysts was evaluated by Hoechst and propidium iodide (PI) staining.

Results

The data showed a high rate of both splitting and developmental efficiency in the frozen-warmed embryos after IES (140% and 71.7%, respectively), followed by chromosomally abnormal embryos (96.8% and 52.5%, respectively). Results of the Hoechst and PI staining showed that the mean ± SD cell numbers of the control group were higher (113.11 ± 16.01) than that of twins A (donor blastomeres embryos, 58 ± 12.2) and B (recipient blastomeres embryos, 50.4 ± 8.5), respectively.

Conclusion

Chromosomally normal embryos enrolled in IES are more potent to develop into viable blastocysts. For research purposes, 1PN and 3PN embryos are the best options for splitting procedures, regardless of the poor quality of developed blastocysts.

Clinical outcomes of MII oocytes with refractile bodies in patients undergoing ICSI and single frozen embryo transfer

PURPOSE

This study aimed to analyze whether the presence of refractile bodies (RFs) negatively affects fertilization, embryo development, and/or implantation rates following intracytoplasmic sperm injection (ICSI).

METHODS

This retrospective embryo cohort study involved a total of 272 patients undergoing ICSI treatment of blastocyst cryopreservation.

RESULTS

In the study, no significant differences were found regarding 2PN formation rates between RF(+) (76.5%) and RF(-) oocytes (77.2%). However, the blastocyst formation rate on Day 5 in RF(+) oocytes was 45.8%, which was significantly lower than that of 52.2% in RF(-) oocytes (aOR 0.74, 95% CI 0.59-0.93, P = .011). Implantation rates were also significantly lower in RF(+) oocytes (24.2%) as compared to RF(-) oocytes (42.2%) (aOR 0.46, 95% CI 0.26-0.78, P = .005). Furthermore, the implantation rate of RF(+) oocytes (28.6%), when high-quality blastocysts were transferred, was significantly lower than that of RF(-) oocytes (46.1%) (aOR 0.50, 95% CI 0.25-0.96, P = .043).

CONCLUSION

Our results suggest that oocytes with the presence of RFs have a lower potential for blastocyst development. Even when they develop into high-quality blastocysts, the chances of implantation are reduced.

Growth differentiation factor 9 and cumulus cell supplementation in in vitro maturation culture media enhances the viability of human blastocysts

Objective

In vitro maturation (IVM) of immature oocytes can be useful for some infertile patients. In IVM programs, the rates of embryo formation and pregnancy are low. Therefore, it is essential to recognize the main factors involved in regulating oocyte maturation in vitro. The purpose of this study was to investigate the effects of growth differentiation factor 9 (GDF9) and cumulus cell (CC) supplementation in IVM medium on the rates of embryo formation and viability of human blastocysts.

Methods

A total of 80 germinal vesicle oocytes from stimulated cycles underwent an IVM program. The oocytes were divided into four groups, where group I consisted of IVM media only and served as the control, group II consisted of IVM+CCs, group III consisted of IVM+GDF9 (200 ng/mL), and group IV consisted of IVM+CCs+GDF9 (200 ng/mL). Intracytoplasmic sperm injection was performed on the IVM oocytes, and the cleavage embryos that were generated were vitrified. Following thawing, the embryos were cultured for 3 additional days, and the viability rates of the developed blastocysts were determined.

Results

The maturation rate of the oocytes did not differ significantly across the four groups. The fertilization rate in group II was significantly higher than that in the control group (76.5% vs. 46.2%). Embryo formation was significantly more frequent in all experimental groups than in the control group, while blastocyst formation did not show significant differences in the three experimental groups compared to the control. The mean viability rates in groups II, III, and IV were 58.16%, 55.91%, and 55.95%, respectively, versus 37.78% in the control group (p<0.05).

Conclusion

Supplementation of IVM culture media with GDF9 and CCs enhanced the fertilization, embryo formation, and viability rates of blastocysts generated from vitrified cleavage embryos.

Vitrification has detrimental effects on maturation, viability, and subcellular quality of oocytes post IVM in cancerous women: An experimental study

Background

In vitro maturation (IVM) of immature oocytes retrieved from ovarian tissue has been considered as a valuable approach for fertility preservation in cancerous patients.

Objective

To evaluate the efficacy of vitrification on oocyte maturation, survival rates, as well as the subcellular oocyte quality post IVM.

Materials and Methods

The ovarian cortexes from 19 women with cervix and uterine malignancy aged 21-39 yr were collected. Cumulus-oocyte complexes were aspirated from all visible antral follicles. 102 immature oocytes were collected, and 43 oocytes were detected appropriately for IVM (control group). Also, 59 immature oocytes were vitrified, then matured in vitro (IVM) in two groups: with Growth/differentiation factor 9 (GDF9) (group 1) and without GDF9 (group 2) supplementation. Rates of oocytes viability, maturation, and survival along with meiotic spindle visualization and zona pellucida birefringence were assessed with Polyscope.

Results

The rate of maturation was significantly higher in controls (55.8%) compared to the other groups. Maturation rate was 23.3% in oocytes cultured in IVM medium enriched with GDF9, and 27.6% in those cultured in IVM medium lacking GDF9 (p = 0.86). Also, the meiotic spindle was present in 74.4% of control oocytes which was significantly higher than the other groups. The proportion of high zona pellucida birefringence was higher in the controls when compared with group 1 (51.2% vs. 23.3%, respectively, p = 0.04).

Conclusion

Vitrification had a detrimental effect on oocyte maturation, viability as well as the subcellular quality of the oocytes after IVM in cancerous women.

Does rescue in vitro maturation of germinal vesicle stage oocytes impair embryo morphokinetics development?

SummaryCurrently, rescue in vitro maturation (IVM) is not a routine method in assisted reproductive treatment (ART) programmes but is a promising procedure for ART to improve IVM. The aim of this study was to compare embryo morphokinetics of germinal vesicles (GV) with metaphase II (MII) oocytes from controlled ovarian hyperstimulation (COH) cycles by time-lapse photography monitoring (TLM). Morphokinetics of the same number of embryos derived from the in vivo (group I) and rescue of in vitro matured oocytes (group II) from 310 patients were analyzed and compared retrospectively. The time to form second PB extrusion (tPB2), time of pronuclei appearance (tPNa), time of pronuclei fading (tPNf) and time of two to eight discrete cells (t2-t8) were assessed. Abnormal cleavage patterns such as uneven blastomeres at the two-cell stage, cell fusion (Fu), trichotomous mitoses (TM), and the rates of embryo arrest were assessed. These data showed that tPB2, tPNa, tPNf, t2, t3 and t4 stages took place later in group II compared with group I (P<0.001, P=0.017, P<0.001, P<0.001, P<0.001, P<0.001, respectively). The rates of uneven blastomeres, Fu, TM, and embryo arrest were increased significantly in group II compared with group I (P=0.001, P<0.001, P=0.003, P<0.001, respectively). Based on the exact annotation of timing parameters and cleavage patterns, the present data agreed with the concept that rescue IVM of oocytes negatively influences embryo morphokinetics. Therefore, cautious use of embryos derived from rescue IVM of GV oocytes should be made.

Pronuclear pattern does not predict morphokinetics behavior in human embryos

The purpose was to investigate the correlation between pronuclei (PN) morphology and morphokinetic behaviors of derived embryos with time lapse monitoring (TLM) in assisted reproduction setting. Over time, PN morphology from PN appearance (PNA) to PN fading (PNF), PNF according to size, contact, number and position of nuclear precursor bodies (NPBs) within each PN and morphokinetics variables, including absolute time points, relative timing parameters, cleavage patterns and arrest rate, were evaluated using TLM. There were insignificant relationship between morphokinetics variables including tBP2, tPNA, tPNF, t2, t3, t4, t5, t6, t7, t8, S1, CC2, S2 and Z scoring according Z1 to Z4 (p > .05). Also, an insignificant relationship was noticed between uneven blastomeres, reverse cleavage embryos and Z scoring (p > .05). However, there were significant correlations between the rates of direct and arbitrary cleavage as well as arrested embryos and Z scores. Combined PN morphology and embryo kinetic evaluation were suggested in assisted reproduction programs.

Development of in vitro maturation techniques for clinical applications

In vitro maturation (IVM) refers to maturation in culture of immature oocytes at different stages that may or may not have been exposed to short courses of gonadotropins. The source of immature oocytes is an important feature for subsequent embryonic development, pregnancy, and healthy live births. IVM is an effective treatment that has already achieved significant outcomes of acceptable pregnancy and implantation rates and has led to the births of several thousand healthy babies. As the development of IVM treatment continues, an attractive possibility for improving the already successful outcome is to combine a natural-cycle in vitro fertilization (IVF) treatment with immature-oocyte retrieval followed by IVM of those immature oocytes. If the treatment processes can be simplified for immature-oocyte retrieval, different types of infertile women may be able to take advantage of these treatments. Mild-stimulation IVF combined with IVM treatment may represent a viable alternative to the standard treatment. Although IVM treatment is still considered to be experimental, it is now time to reconsider the IVM technology and its development. Mild-stimulation IVF combined with IVM may prove to be not just alternatives to standard treatments, but potentially first-line treatment choices.

Oocyte morphology and embryo morphokinetics in an intra-cytoplasmic sperm injection programme. Is there a relationship?

The aim was to investigate the relationship between the morphological parameters of metaphase II (MII) oocytes with morphokinetic variables of embryos following an intra-cytoplasmic sperm injection (ICSI) procedure. Morphokinetic behaviour and abnormal cleavage patterns of 334 zygotes were analyzed using time-lapse monitoring (TLM). In addition, oocyte morphology was assessed in relation to embryo morphokinetic (absolute time point, including time to second polar body (PB) extrusion (ESPB), pronuclei (PN) appearance (PNA), PN fading (PNF), time to 2-cells (t2), 3c (t3), 4c (t4), 5c (t5), 6c (t6), 7c (t7), 8c (t8) and relative timing parameters (S1, S2, CC2 and CC3). Also, cleavage patterns (uneven blastomeres, reverse, direct and arbitrary) were assessed. The data showed that 79% of the normal fertilized oocytes had at least one abnormal morphological characteristic. Intra-cytoplasmic abnormalities were observed in 12% of the oocytes. Also, extra-cytoplasmic abnormalities were noticed in 29%, while combined intra- and extra-cytoplasmic abnormalities were responsible for the remaining 38% of the oocytes. Nearly all cleavage and interval times, except extrusion of the ESPB time (P = 0.003), were similar between normal and abnormal morphologic oocytes (P < 0.05). Moreover, there was significant relationship for oocyte morphology abnormalities and cleavage patterns, including uneven blastomere (P = 0.037), reverse cleavage (RC) (P = 0.0), direct (P = 0.001) and arbitrary cleavages (P = 0.001). Using TLM, the cleavage patterns of embryos were affected by the quality of MII oocytes in the ICSI cycles. So, evaluation of oocyte morphology with subsequent embryo morphokinetics is recommended in assisted reproductive programmes.

Analysis of meiotic spindle and zona pellucida birefringenceof IVM oocytes in PCOS patients

BACKGROUND/AIM

Polycystic ovarian syndrome (PCOS) is one of the most common causes of infertility. One of the best therapeutic options for PCOS patients is intracytoplasmic sperm injection (ICSI). In vitro maturation (IVM) can also be a useful technique for these women. The goal of this study was to evaluate both the zona pellucida (ZP) birefringence and meiotic spindle (MS) of in vivo- and in vitro-matured oocytes from PCOS patients using the PolScope system.

MATERIALS AND METHODS

Immature oocytes undergoing IVM and MII oocytes were obtained from PCOS patients in an ICSI program. Using PolScope, the presence of MS and ZP birefringence was assessed in both in vivo-matured oocytes (n = 32) and IVM oocytes (n = 24). Oocytes were classified as having highly birefringent (HB) ZP and lowly birefringent (LB) ZP. Furthermore, the rates of fertilization after ICSI were evaluated.

RESULTS

The maturation rate was 68.5% after IVM. The percentage of a HB-ZP was significantly higher in the IVM oocytes than in vivo-matured ones (58.3% vs. 31.2%, respectively; P = 0.04). There were similar outcomes for the fertilization rates and MS detection between the two groups (P = 0.80 and P = 0.53, respectively).

CONCLUSION

Clinical IVM is a safe technology for the maturation and maintenance of oocyte integrity in PCOS patients. The use of the noninvasive PolScope is recommended for detection of healthy oocytes in ICSI.

Noninvasive assays of in vitro matured human oocytes showed insignificant correlation with fertilization and embryo development

PURPOSE

Recently, the upgrading of in vitro maturation (IVM) of human oocytes as a promising strategy has emerged in assisted reproductive technology (ART). The goal was to evaluate the correlation of the in vitro matured oocytes selected on the basis of the zona pellucida (ZP) birefringence and meiotic spindles (MS) detection with fertilization and subsequent embryo development in ICSI program.

METHODS

A total of 168 immature oocytes [germinal vesicle (n = 140) and metaphase I (n = 28)] obtained from patients undergoing oocytes retrieval for ICSI. After in vitro culture for 24-40 h, 112 (67 %) oocytes reached to MII stage. Using a polarized microscopy, the presence of MS and ZP birefringence were assessed in matured oocytes, followed by ICSI performance.

RESULTS

The rates of fertilization in oocytes with spindles (51.3 %) were similar to that of the oocytes without spindles (50.7 %; P = 1.00). Moreover, the fertilization rates in high birefringence (HB) oocytes was not statistically different than oocytes with low birefringence (LB) (P = 0.44). The findings also showed that 64.9 % of the fertilized oocytes developed to embryos, in which 33.3 % were derived from spindle-detected oocytes. Regarding the ZP birefringence, 35.5 % of the embryos were derived from HB oocytes.

CONCLUSIONS

There were insignificant relationships between the MS detection and ZP birefringence score with the rates of fertilization and embryo development in IVM oocytes.

Use of both cumulus cells' transcriptomic markers and zona pellucida birefringence to select developmentally competent oocytes in human assisted reproductive technologies

BACKGROUND

Selection of the best oocyte for subsequent steps of fertilization and embryo transfer was shown to be the crucial step in human infertility treatment procedure. Oocyte selection using morphological criteria mainly Zona pellucida (ZP) has been the gold standard method in assisted reproductive technologies (ART) clinics, but this selection approach has limitations in terms of accuracy, objectivity and constancy. Recent studies using OMICs-based approaches have allowed the identification of key molecular markers that quantitatively and non-invasively predict the oocyte quality for higher pregnancy rates and efficient infertility treatment. These biomarkers are a valuable reinforcement of the morphological selection criteria widely used in in vitro fertilization (IVF) clinics. In this context, this study was designed to investigate the relationship between transcriptomic predictors of oocyte quality found by our group and the conventional morphological parameters of oocyte quality mainly the ZP birefringence.

RESULTS

Microarray data revealed that 48 and 27 differentially expressed candidate genes in cumulus cells (CCs) were respectively overexpressed and underexpressed in the ZGP (Zona Good Pregnant) versus ZBNP (Zona Bad Non Pregnant) groups. More than 70% of previously reported transcriptomic biomarkers of oocyte developmental competence were confirmed in this study. The analysis of possible association between ZP birefringence versus molecular markers approach showed an absence of correlation between them using the current set of markers.

CONCLUSIONS

This study suggested a new integrative approach that matches morphological and molecular approaches used to select developmentally competent oocytes able to lead to successful pregnancy and the delivery of healthy baby. For each ZP birefringence score, oocytes displayed a particular CCs' gene expression pattern. However, no correlations were found between the 7 gene biomarkers of oocyte developmental potential and the ZP birefringence score. Further studies using larger lists of candidate markers are required to identify suitable genes that are highly correlated with the morphological criteria, and therefore able to reinforce the accuracy of oocyte selection and the effectiveness of infertility treatment.