Polarized light microscopy-detectable structures of human oocytes and embryos are related to the likelihood of conception in IVF

The Implications of the Meiotic Spindle Visualization Technique on In Vitro Fertilization (IVF) Outcome in a Perimenopausal Patient

An infertile couple visited an in vitro fertilization center situated in Maharashtra, India, seeking treatment for primary infertility. The 39-year-old premenopausal woman had a history of two intrauterine inseminations and intracytoplasmic sperm injections (ICSI), along with a history of tuberculosis from six years, and a normal hormonal range. The male was normozoospermic. The patient was given a gonadotropin-releasing hormone antagonist treatment and triggered before 36 hours of ovum pickup (OPU), but the cycle failed. Due to normal blood parameters, it was decided to use an optimal microscope using a polarizing filter to check the timing of meiotic spindle (MS) formation in the oocytes. The patient was triggered again for OPU, and during the procedure, 14 oocytes were retrieved. It was decided to perform ICSI after seven and a half hours of OPU post-observation of MS formation around the same hour. On day 21, the patient was suggested for embryo transfer (ET), where two blastocysts (4AA and 3AA) were transferred into the uterus. After a successful ET, the patient was discharged from the hospital. On day 14, a beta-human chronic gonadotrophin report revealed a positive pregnancy (910 mIU/mL).

Predictive value of cytoplasmic granulation patterns during in vitro fertilization in metaphase II oocytes: Part I, poor-prognosis patients

OBJECTIVE

To determine whether 4 cytoplasmic granulation patterns of human metaphase II oocytes have a predictive value for in vitro fertilization outcomes.

DESIGN

A retrospective cohort study.

SETTING

An academically affiliated private clinical infertility and research center.

PATIENT(S)

A total of 2,690 consecutive fresh autologous oocytes collected from women aged 41.2 ± 5.0 years between 2017 and 2019.

INTERVENTION(S)

Determination of granulation pattern in every oocyte during intracytoplasmic sperm injection as fine, central, dispersed, and newly introduced uneven granulations.

MAIN OUTCOME MEASURE(S)

Fertilization outcomes (2 pronuclei [2PN], <2PN, and >2PN rates), pregnancy, and live birth rates for different granulation patterns at different ages.

RESULT(S)

Fine granulation produced the highest 2PN rate, followed by central, uneven, and dispersed granulation (91.8%, 83.9%, 77.9%, and 54.8%, respectively). Differences in fertilization were surprisingly relatively independent of age and other variables. Overall, compared with fine granulation, dispersed granulation resulted in lower pregnancy rates (4.6% vs. 10.7%) and known-outcome analysis (1.3% vs. 5.6%) as well as lower live birth rates (3.0% vs. 8.9%) and known-outcome analysis (0.6% vs. 5.6%). The known-outcome analysis demonstrated that uneven granulation had lower live birth rates than fine granulation (2.3% vs. 5.6%). Unexpectedly, the ooplasm granulation patterns were largely disassociated from embryo morphologic grades.

CONCLUSION(S)

We, for the first time, demonstrated that 4 distinct cytoplasmic granulation patterns in metaphase II oocytes had, largely independent of age and other variables, a predictive value for fertilization, pregnancy, and live birth outcomes in in vitro fertilization cycles of poor-prognosis patients. These data suggest that upstream ooplasm granulation patterns deserve closer attention in terms of embryo selection.

Current Advancements in Noninvasive Profiling of the Embryo Culture Media Secretome

There have been over 8 million babies born through in vitro fertilization (IVF) and this number continues to grow. There is a global trend to perform elective single embryo transfers, avoiding risks associated with multiple pregnancies. It is therefore important to understand where current research of noninvasive testing for embryos stands, and what are the most promising techniques currently used. Furthermore, it is important to identify the potential to translate research and development into clinically applicable methods that ultimately improve live birth and reduce time to pregnancy. The current focus in the field of human reproductive medicine is to develop a more rapid, quantitative, and noninvasive test. Some of the most promising fields of research for noninvasive assays comprise cell-free DNA analysis, microscopy techniques coupled with artificial intelligence (AI) and omics analysis of the spent blastocyst media. High-throughput proteomics and metabolomics technologies are valuable tools for noninvasive embryo analysis. The biggest advantages of such technology are that it can differentiate between the embryos that appear morphologically identical and has the potential to identify the ploidy status noninvasively prior to transfer in a fresh cycle or before vitrification for a later frozen embryo transfer.

Effect of a Combination of Myo-Inositol, Alpha-Lipoic Acid, and Folic Acid on Oocyte Morphology and Embryo Morphokinetics in non-PCOS Overweight/Obese Patients Undergoing IVF: A Pilot, Prospective, Randomized Study

Herein we aimed at assessing whether Myo-Inositol (MI), Alpha–Lipoic acid (ALA), and Folic acid (FA) could improve oocyte quality and embryo development in non-PCOS overweight/obese women undergoing IVF. Three hundred and twenty-four mature oocytes were obtained from non-PCOS overweight/obese patients, randomized to receive either MI, ALA, and FA (MI + ALA + FA group, n = 155 oocytes) or FA alone (FA-only group, n = 169 oocytes). Oocytes were examined using Polarized Light Microscopy to assess morphological features of zona pellucida (ZP) and meiotic spindle (MS). One hundred and seventy-six embryos (n = 84 in the MI + ALA + FA group, n = 92 in the FA-only group) were assessed by conventional morphology on days 2 and 5, as well as using the Time-Lapse System morphokinetic analysis. A significantly higher ZP retardance, area, and thickness (p < 0.05), and a shorter MS axis (p < 0.05) were observed in the MI + ALA + FA group, suggesting a positive effect on oocyte quality. Conventional morphology evaluation on day 2 showed a higher mean embryo score in the MI + ALA + FA group, whereas embryo morphokinetic was comparable in the two groups. Overall, our data show a possible beneficial effect of the combination of MI, ALA, and FA on oocyte and embryo morphology, encouraging testing of this combination in adequately powered randomized trials to assess their impact of clinical IVF results.

A prospective randomized trial comparing corifollitropin-α late-start (day 4) versus standard administration (day 2) in expected poor, normal, and high responders undergoing controlled ovarian stimulation for IVF

OBJECTIVE

To assess whether corifollitropin-α (CFα) late-start administration (day 4) and standard administration (day 2) can obtain similar oocyte yield and live birth rate.

STUDY DESIGN

A randomized controlled trial.

SETTING

University Hospital IVF Unit.

PATIENTS

One hundred thirteen women undergoing IVF.

INTERVENTIONS

Patients distributed in three subgroups (expected poor, normal, or high responders to FSH) were randomized into two treatment arms: (a) CFα late-start: CFα on day 4 + GnRH antagonist from day 8 + (when needed) recFSH from day 11; (b) CFα standard start: CFα on day 2 + GnRH antagonist from day 6 + (when needed) recFSH from day 9. IVF or ICSI was performed as indicated.

RESULTS

Considering the whole study group, the late-start regimen obtained comparable oocyte yield (8.9 ± 5.6 vs. 8.8 ± 6.2; p = n.s.), cPR/started cycle (25% vs. 31.6%, p = n.s.), and cumulative live birth rate (LBR)/ovum pickup (OPU) (29.2% vs. 37.7%, p = n.s.) than the standard regimen. The outcome of the two regimens was comparable in the two subgroups of high and normal responders. Differently, in poor responders, oocyte yield was similar, but LBR/OPU was significantly lower with late-start CFα administration that caused 40% cancellation rate due to monofollicular response. ROC curves showed that the threshold AMH levels associated with cycle cancellation were 0.6 ng/ml for late-start regimen and 0.2 ng/ml for standard regimen.

CONCLUSION

CFα may be administered on either day 2 or day 4 to patients with expected high or normal response to FSH without compromising oocyte yield and/or live birth rate. Differently, late-start administration is not advisable for expected poor responders with AMH ≤ 0.6 ng/ml.

TRIAL REGISTRATION

NCT03816670.

Does the meiotic spindle really predicts embryo implantation and live birth rates? An update

SummaryThe aim of this study was to determine the capacity of the meiotic spindle (MS) to predict embryo implantation and live birth rates. For this purpose, we performed a broad systematic literature search. Of all publications retrieved, only those in which the implantation rates were related to some characteristics of the MS were evaluated. Despite the different methodology used in all the chosen studies, presence of the MS in oocytes was found to be positively associated with embryo implantation. Moreover, high retardance values, as well as strict criteria of normality in the MS structure, are significantly related to higher embryo implantation numbers and live birth rates.

Zona pellucida gene mRNA expression in human oocytes is related to oocyte maturity, zona inner layer retardance and fertilization competence

STUDY QUESTION

Do the mRNA expression levels of zona pellucida (ZP) genes, ZP1, 2, 3 and 4 in oocyte and cumulus cells (CC) reveal relevant information on the oocyte?

SUMMARY ANSWER

The ZP mRNA expression in human oocytes is related to oocyte maturity, zona inner layer (IL) retardance and fertilization capacity.

WHAT IS KNOWN ALREADY

ZP structure and birefringence provide useful information on oocyte cytoplasmic maturation, developmental competence for embryonic growth, blastocyst formation and pregnancy. In order to understand the molecular basis of morphological changes in the ZP, in the current study, the polarized light microscopy (PLM) approach was combined with analysis of the expression of the genes encoding ZP1, 2, 3 and 4, both in the oocytes and in the surrounding CC.

STUDY DESIGN, SIZE, DURATION

This is a retrospective study comprising 98 supernumerary human cumulus oocyte complexes (COC) [80 Metaphase II (MII), 10 Metaphase I (MI) and 8 germinal vesicle (GV)] obtained from 39 patients (median age 33.4 years, range 22-42) after controlled ovarian stimulation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Single oocytes and their corresponding CC were analysed. Oocytes were examined using PLM, and quantitative RT-PCR was performed for ZP1, 2, 3 and 4 in these individual oocytes and their CC. Ephrin-B2 (EFNB2) mRNA was measured in CC as a control. Presence of ZP3 protein in CC and oocytes was investigated using immunocytochemistry. Data were analysed using one-parametric and multivariate analysis and were corrected for the potential impact of patient and cycle characteristics.

MAIN RESULTS AND THE ROLE OF CHANCE

Oocytes contained ZP1/2/3 and 4 mRNA while in CC only ZP3 was quantifiable. Also ZP3 protein was detected in human CC. When comparing mature (MII) and immature oocytes (MI/GV) or their corresponding CC, ZP1/2 and 4 expression was lower in mature oocytes compared to the expression in immature oocytes (all P < 0.05) and ZP3 expression was lower in the CC of mature oocytes compared to the expression in CC of immature oocytes (P < 0.05). This coincided with a significantly smaller IL-ZP area and thickness in mature oocytes than in immature oocytes (all P < 0.05). In mature oocytes, IL-ZP retardance was significantly correlated with the expression of all four ZP mRNAs (all P < 0.05). The oocyte ZP3 expression was the main predictor of the fertilization capacity, next to IL-retardance and IL-thickness. Using stepwise regression analysis, IL-thickness combined with EFNB2 expression in CC and the patient's ovarian response resulted in a noninvasive oocyte fertilization prediction model.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

This is a retrospective study and the relation of oocyte mRNA levels to fertilization capacity is indirect as oocyte gene expression analysis required lysis of the oocyte.

WIDER IMPLICATIONS OF THE FINDINGS

Overall relations between PLM observations, mRNA expression changes and intrinsic oocyte competence were successfully documented. As such PLM and CC gene expression are confirmed as valuable noninvasive techniques to evaluate oocyte competence.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by University of Torino, Italy, WFWG UZ-Brussel and Agentschap voor Innovatie door Wetenschap en Technologie IWT 110680, Belgium. All authors declare that their participation in the study did not involve actual or potential conflicts of interests.

Oocyte polarized light microscopy, assay of specific follicular fluid metabolites, and gene expression in cumulus cells as different approaches to predict fertilization efficiency after ICSI

BACKGROUND

The complex relationship between oocyte morphology, specific follicular fluid metabolites, gene expression in cumulus granulosa cells, and oocyte competence toward fertilization and embryo development still needs further clarification.

METHODS

Forty-six oocytes retrieved from the largest pre-ovulatory follicle of patients undergoing intra-cytoplasmic sperm injection (ICSI) were considered assessing: (a) oocyte morphological characteristics at polarized light microscopy (PLM), (b) specific follicular fluid (FF) metabolites previously suggested to influence oocyte competence (AMH, markers of redox status and of cytotoxicity), (c) transcription of AMH and AMH type II receptor genes in cumulus cells. Data were analyzed using mono-parametric tests and multivariable logistic analysis in order to correlate morphological and biochemical data with fertilization.

RESULTS

Comparing normally fertilized oocytes (n = 29, F group) with unfertilized (n = 17, nF group) we observed that: (a) the meiotic spindle area and major axis were significantly higher in nF group and in fertilized oocytes undergoing an early embryo development arrest; (b) AMH level in FF was comparable in F and nF groups; (c) the FF of nF group contained significantly higher levels of cytotoxicity (lactate dehydrogenase) and oxidative stress (Cu,Zn-superoxide dismutase, catalase, 4-hydroxynonenal-protein conjugates) markers; (d) cumulus cells of nF group showed significantly higher AMH receptor type II gene expression.

CONCLUSIONS

Taken together, these observations suggest that an excessive cytotoxicity level can alter AMH signal transduction within cumulus cells, in turn leading to partial inhibition of aromatase activity, altered cytoplasmic maturation and increased oxidative stress, factors able to impair oocyte fertilization competence and embryo growth.

Evaluation of equine oocyte developmental competence using polarized light microscopy

The purpose of this study was to observe in vitro-matured equine oocytes with an objective computerized technique that involves the use of a polarized light microscope (PLM) in addition to the subjective morphological evaluation obtained using a classic light microscope (LM). Equine cumulus-oocyte complexes (COCs, n = 922) were subjected to different in vitro maturation times (24, 36 or 45 h), however, only 36-h matured oocytes were analyzed using CLM. The 36-h matured oocytes that reached maturity were parthenogenetically activated to evaluate the quality and meiotic competence. Average maturation percentages per session in groups 1, 2 and 3 (24-, 36- and 45-h matured oocytes respectively) were 29.31 ± 13.85, 47.01 ± 9.90 and 36.62 ± 5.28%, whereas the average percentages of immature oocytes per session were 28.78 ± 20.17, 7.83 ± 5.51 and 22.36 ± 8.39% respectively. The zona pellucida (ZP) birefringent properties were estimated and correlated with activation outcome. ZP thickness and retardance of the inner layer of the zona pellucida (IL-ZP) were significantly increased in immature oocytes compared with mature oocytes (P < 0.001 and P < 0.01 respectively). The comparison between parthenogenetically activated and non-activated oocytes showed a significant increase in the area and thickness of the IL-ZP in parthenogenetically activated oocytes (P < 0.01). These results show that the 36-h in vitro maturation (IVM) protocol allowed equine oocytes to reach maturity, and PLM observation of ZP can be used to distinguish mature and immature oocytes as well as activated and non-activated oocytes.

Developmental competence of immature oocytes aspirated from antral follicles in patients with gynecological diseases

BACKGROUND

In vitro maturation (IVM) of immature oocytes collected from ovary has been proposed for fertility preservation. In addition, quality of oocytes post IVM is one of the factors determining its developmental competence. By using the non-invasive Polscope system, both meiotic spindle (MS) and zona pellucida (ZP) can be assessed in living oocytes.

OBJECTIVE

The aim was to investigate the developmental potential of immature oocytes retrieved from ovarian tissue after IVM, as a method for fertility preservation, in patients with gynecological diseases.

MATERIALS AND METHODS

The ovarian cortex from 26 patients with malignant and benign diseases (21-45 years old), were obtained directly from collaborating hospitals, and transported to the IVF center on ice. In total 61 immature oocytes were aspirated, of which 18 (29.5%) were degenerated and discarded. The remaining 43 (70.5%) healthy oocytes were cultured in IVM culture media for 48 hr. The rate of maturity was assessed, and the ZP birefringence and MS were imaged with Polscope technology.

RESULTS

Overall 43 immature oocytes underwent IVM technology, of which 30.2% reached viable metaphase II (MII) oocytes. The ovarian tissues of 9 (34.6%) women were lacking oocytes at any stage. During polarized light microscopy examination, MS could be visualized only in one of the MII oocytes, but high ZP birefringence's were observed in the majority of the oocytes post IVM (61.5%).

CONCLUSION

Oocytes maturation post IVM from unstimulated ovaries showed a good developmental competence in gynecologic patients. Further studies should be performed to advance the oocyte maturation program, such as co-culture system, for fertility preservation.

Quantitative polarized light microscopy of human cochlear sections

Dysfunction of the inner ear is the most common cause of sensorineural hearing loss, which is the most common sensory deficit worldwide. Conventional imaging modalities are unable to depict the microanatomy of the human inner ear, hence the need to explore novel imaging modalities. We provide the first characterization of the polarization dependent optical properties of human cochlear sections using quantitative polarized light microscopy (qPLM). Eight pediatric cadaveric cochlear sections, aged 0 (term) to 24 months, were selected from the US National Temporal Bone Registry, imaged with qPLM and analyzed using Image J. Retardance of the bony otic capsule and basilar membrane were substantially higher than that of the stria vascularis, spiral ganglion neurons, organ of Corti and spiral ligament across the half turns of the spiraling cochlea. qPLM provides quantitative information about the human inner ear, and awaits future exploration in vivo.

Inducible nitric oxide synthase and heme oxygenase 1 are expressed in human cumulus cells and may be used as biomarkers of oocyte competence

The interplay between oocyte and surrounding cumulus cells (CCs) during follicular growth influences oocyte competence to undergo fertilization and sustain embryo development. The expression of many genes and proteins in CCs has been suggested as potential biomarker of oocyte competence in human in vitro fertilization (IVF). In the present study, we analyzed 90 human cumulus-oocyte complexes obtained during IVF procedure: 30 CCs were analyzed using quantitative real-time polymerase chain reaction and 60 CCs using Western blotting analysis to detect gene and protein expression of some enzymes related to oxidative stress, that is, the 3 nitric oxide synthase (NOS) isoforms and heme oxygenase 1 (HO-1). In the group of 60 CCs, we also investigated the expression and phosphorylation of IkBα, a known inhibitor of the nuclear factor κB (NF-κB) pathway, which controls several redox-sensitive genes. The expression of the messenger RNAs (mRNAs) was related to the oocyte morphological analysis performed by polarized light microscopy and to the occurrence of normal fertilization after intracytoplasmic sperm injection. We observed that the amount of iNOS and HO-1 mRNAs and proteins is significantly higher, and that in the meanwhile the NF-κB pathway is activated, in CCs corresponding to oocytes that were not fertilized in comparison to CCs whose corresponding oocyte showed normal fertilization. Instead, no correlation between the fertilization and the oocytes' morphological data was observed. These results suggest that the increase in iNOS and HO-1 mRNAs expression in CCs is a negative index of oocyte fertilizability and might be an useful tool for oocyte selection.

Pregnancy with oocytes characterized by narrow perivitelline space and heterogeneous zona pellucida: is intracytoplasmic sperm injection necessary?

PURPOSE

This retrospective study analyzed fertilization protocols and pregnancy outcomes for oocytes with with narrow perivitelline space and heterogeneous zona pellucid (NPVS/HZP).

METHODS

In 63 in-vitro fertilization cycles filled with NPVS/HZP oocytes (abnormal oocytes group) and 521 cycles with normal oocytes (normal oocytes group), major clinical and laboratory parameters were recorded and compared in different fertilization cycles (conventional IVF cycles, rescue ICSI cycles, and traditional ICSI cycles).

RESULTS

NPVS/HZP oocytes meant lower MIIoocytes rates in both IVF and ICSI cycles compared with normal oocytes (p < 0.05). The 2PN rates for abnormal oocytes were significantly lower than those for normal oocytes in both conventional IVF cycles (58.8% VS 71.3%, P < 0.05) and rescue ICSI cycles (58.0% VS 78.0%, P = 0.0000). The high-quality embryo rates in normal oocytes groups were significantly higher than those in abnormal oocytes groups in different fertilization cycles (52.2% VS 35.0%, P < 0.01; 42.9% VS 23.9%, P < 0.001; 50.6% VS 31.0%, P = 0.0000, respectively). No clinical pregnancy was obtained from abnormal oocytes in 11 conventional IVF cycles. The clinical pregnancy rates in rescue ICSI and traditional ICSI cycles were comparatively lower in abnormal oocytes groups, but there was no significant difference as compared with normal oocytes groups (35.0% VS 48.1% and 26.7% VS 50.7%, P > 0.05, respectively).

CONCLUSIONS

Retrieval of oocytes characterized by NPVS/PZP from cycle to cycle was one of the reasons for obscure infertility. ICSI may be the right way to avoid fertilization failure and get pregnancy in women with NPVS/HZP oocytes.

Intracellular glutathione content, developmental competence and expression of apoptosis-related genes associated with G6PDH-activity in goat oocyte

PURPOSE

To associate glucose-6-phosphate dehydrogenase (G6PDH) activity in goat oocytes with intracellular glutathione (GSH) content, meiotic competence, developmental potential, and relative abundance of Bax and Bcl-2 genes transcripts.

METHODS

Goat oocytes were exposed to brilliant cresyl blue (BCB) staining test and categorized into BCB(+) (blue-cytoplasm), and BCB(-) (colorless-cytoplasm) groups. A group of oocytes were not exposed to BCB test and was considered as a control group. After maturation in vitro, a group of oocytes were used for determination of nuclear status and intracellular GSH content while another group was subjected to parthenogenetic activation followed by in vitro embryo culture.

RESULTS

We found that BCB(+) oocytes not only yielded higher rate of maturation, but also showed an increased level of intracellular GSH content than BCB(-) and control oocytes. Furthermore, BCB(+) oocytes produced more blastocysts than BCB(-) and control oocytes. Our data revealed that the expression of anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) genes were interacted with G6PDH-activity in mature oocyte, their surrounding cumulus cells, and blastocyst-stage embryos.

CONCLUSIONS

The results of this study demonstrate that selection of goat oocytes based on G6PDH-activity through the BCB test improves their developmental competence, increases intracellular GSH content, and affects the expression of the apoptosis-related genes.