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

Embryological characteristics and clinical outcomes of oocytes with different degrees of abnormal zona pellucida during assisted reproductive treatment

Abnormalities in the zona pellucida (ZP) adversely affect oocyte maturation, embryo development and pregnancy outcomes. However, the assessment of severity is challenging. To evaluate the effects of different degrees of ZP abnormalities on embryo development and clinical outcomes, in total, 590 retrieval cycles were scored and divided into four categories (control, mild, moderate and severe) based on three parameters: perivitelline space, percentage of immature oocytes and percentage of oocytes with abnormal morphology. As the severity of abnormal ZP increased, both the number of retrieved oocytes and mature oocytes decreased. The fertilization rate did not differ significantly among groups. The rates of embryo cleavage and day-3 high-quality embryos in the mild group and the moderate group did not vary significantly between the two groups but were significantly higher than those in the severe group. The blastulation rates of the abnormal ZP groups were similar; however, they were lower than those of the control group. Moreover, the cycle cancellation rate of the severe abnormal ZP group was as high as 66.20%, which was significantly higher than that of the other three groups. Although the rates of cumulative clinical pregnancy and live births were lower than those in the control group, they were comparable among the abnormal ZP groups. There were no differences in the neonatal outcomes of the different groups. Together, ZP abnormalities show various degrees of severity, and in all patients regardless of the degree of ZP abnormalities who achieve available embryos, there will be an opportunity to eventually give birth.

The effects of H22 tumor on the quality of oocytes and the development of early embryos from host mice: A single-cell RNA sequencing approach

The association between cancer and female reproduction remains largely unknown. Here we investigated the quality of oocytes and the developmental potential of zygotes using H22 tumor-bearing mice model. The results showed that the number of oocytes was decreased in tumor-bearing mice compared with the control mice, and accompanied scattered chromosomes was observed. Further study revealed an abnormal epigenetic reprogramming occurred in the zygotes from the H22 tumor-bearing mice, as exemplified by the aberrant 5hmC/5mC modifications in the pronuclei. Finally, single-cell RNA sequencing was performed on the oocytes collected from the H22 tumor-bearing mice. Our data showed that 45 of the 202 differentially expressed genes in tumor-bearing group were closely associated with oocyte quality. Protein interaction analysis indicated that the potential interaction among these 45 genes. Collectively, our study uncovered that the quality of oocytes and early embryonic development were affected by H22 tumor bearing via the altered expression patterns of genes related with reproduction, providing new insights into the reproductive capability of female cancer patients.

Embryological Characteristics of Human Oocytes With Agar-Like Zona Pellucida and Its Clinical Treatment Strategy

Zona pellucida (ZP) abnormalities are the cause of low fertility or infertility, agar-like ZP is more common in abnormal ZP. The purpose of this exploration is to systematically analyze the fertilization competence of agar-like ZP oocytes, the development characteristics of subsequent embryos as well as the results of embryo transfer, aiming to explore effective clinical treatment strategies. A total of 58 patients with agar-like ZP were set as the case group and the control group involved 3866 patients, in which the patients' oocytes presented normal ZP. BMI, basal hormone levels, and hormone levels were similar in both groups. The case patients suffered significantly longer infertility years than control (p<0.05), and most patients were diagnosed with pelvic inflammatory diseases. A distinct difference was observed in the structure of oocyte corona cumulus complexes between the two groups. The embryo development parameters, which include the rates of cleavage, high-quality embryo, blastocyst, and high-quality blastocyst in the case group were greatly lower than that in the control group (p<0.05). The rates of cumulative clinical pregnancy and live birth were comparable between the two groups. In the subsequent follow-up, thirty-four of the 58 patients receiving intracytoplasmic single sperm injection (ICSI) or early rescue ICSI (R-ICSI) treatment successfully gave birth to babies, and all of the newborns were with no neonatal defects. In addition, the fertilization rate of the R-ICSI group was significantly lower than that of the ICSI group (p<0.05). The occurrence of agar-like ZP impairs the development competence of human oocytes, however, the human oocytes with agar-like ZP can develop into healthy offspring, and an ICSI regimen is the optimal treatment strategy for them.

DYSMORPHISMS OF OOCYTES IN ART PROCEDURES: A LITERATURE REVIEW

Relevance: Assisted reproductive technologies (ART) are rapidly developing and in recent decades have become increasingly important due to the growing number of infertile couples around the world. Human oocytes are the main objects used in ART procedures. Consequently, the quality of oocytes can determine the key parameters of ART. The purpose of this review was to analyze the literature and the results of studies in the field of ART devoted to extracytoplasmic dysmorphisms of human oocytes – morphological changes outside the cytoplasmic structure of oocytes, their effect on fertilization, cleavage, implantation frequency, clinical pregnancy rate, as well as the possibility of their use as biomarkers for predicting the quality of embryos, blastocysts, and their further implantation potential. Materials and Methods: This literature review was based on a search conducted among domestic and foreign publications for 2000-2020 available in Russian and international search systems (PubMed, eLibrary) using the keywords «infertility,” “IVF,” «oocyte,” “morphological assessment of oocytes,” “dysmorphisms of oocytes ,” and “ assisted reproductive technologies.” Results: This literature review contains literature data and the analysis of research results in the field of ART devoted to the morphological qualities and abnormalities (dysmorphisms) of human oocytes. It describes the types of extracytoplasmic abnormalities encountered in the clinical practice of in-vitro fertilization, their effect on fertilization, cleavage, implantation rate, and clinical pregnancy rate, as well as the possibility of their use as biomarkers to predict the quality of embryos and blastocysts and their further implantation potential.

Embryological Characteristics and Clinical Outcomes of Oocytes with Heterogeneous Zona Pellucida During Assisted Reproduction Treatment: A Retrospective Study

Background

The condition of the zona pellucida can be used to predict human oocyte quality. This study investigated the embryological characteristics and clinical outcomes of oocytes with heterogeneous zona pellucida (HZP) during in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).

Material/Methods

This was a retrospective study of IVF and ICSI cycles undertaken at The First Affiliated Hospital of Wenzhou Medical University between June 2006 and March 2016. Cycles involving oocytes with HZP (HZP group) were compared with those involving non-HZP oocytes retrieved on the same day (non-HZP group). Embryological characteristics and clinical outcomes were compared.

Results

There were 29 IVF and 46 ICSI cycles in the HZP group, and 521 IVF and 206 ICSI cycles in the non-HZP group. In ICSI cycles, the rates of MII oocyte and high-quality embryo were lower in the HZP group (p<0.05 vs. non-HZP). In IVF cycles, the MII oocyte (p<0.001), normal fertilization (p<0.001), and cleavage (p<0.001) rates were lower, while the abandoned transfer rate (p<0.001) was higher in the HZP group compared with the non-HZP group. The positive human chorionic gonadotropin (HCG), implantation, pregnancy, and miscarriage rates were similar between groups. Multivariate analysis revealed that the woman’s age (OR=0.916 95% CI 0.873–0.962; p<0.001) and the number of D3 high-quality embryos (OR=1.120 95% CI 1.004–1.249; p=0.043) were associated with pregnancy in IVF cycles, but no significant factors were found in ICSI cycles.

Conclusions

ICSI may help increase the number of viable embryos in cycles with oocytes showing HZP. However, both IVF and ICSI cycles can achieve pregnancy.

Blastulation of a zygote to a hatched blastocyst without any clear cell division: an observational finding in a time-lapse system after in vitro fertilization

PURPOSE

To describe an interesting not previously described morphokinetic finding.

METHODS

Retrospective case report of a couple undergoing controlled ovarian stimulation (COS) followed by in vitro fertilization and blastocyst transfer.

RESULTS

We identified a unique finding of blastulation of a fertilized human zygote after conventional in vitro fertilization. The fertilized zygote did not show any clear cytokinesis until approximately 107 h post insemination, when it started dividing into a blastocyst. By 113 h post insemination, inner cell mass and trophectoderm cells could be clearly distinguished and the blastocyst was completely hatched by 136 h post insemination.

CONCLUSION

Time-lapse systems offer more detailed observations of embryonic development. Here, we report an atypical development of an embryo that was not described previously. We hope to become an insightful discussion among peers and incentive the publication of such findings in the future.

Zona pellucida blocks adenovirus from entering porcine oocytes

Adenovirus is a kind of non-enveloped,double-stranded DNA virus. As a member of the mammalian adenoviruses of the Adenoviridae family, porcine adenovirus causes gastrointestinal disease in piglets. In this study, the modified adenovirus was manipulated to carry a green fluorescence EGFP marker. The modified adenovirus was added to medium199 for co-incubation or microinjected into the cytoplasm of porcine oocytes. The effect of adenovirus on the first polar body extrusion was not significant during porcine oocyte maturation. Our data demonstrated the zona pellucida plays a vital role in porcine oocytes being resistant to modified adenovirus. Additionally, the results suggested that oocytes protect themselves from nonself substances.

Human sperm acrosomal status, acrosomal responsiveness, and acrosin are predictive of the outcomes of in vitro fertilization: A prospective cohort study

The sperm acrosome reaction (AR) is a physiological secretory course of membrane fusion and hydrolytic enzymes, as well as matrix protein release, enabling spermatozoa to penetrate the egg surroundings. An instable acrosomal status before a specific stimulus, insufficient acrosomal responsiveness, or inadequate enzymatic activity of acrosomal content can be detrimental to male fertility. This prospective cohort study was designed to determine whether three human sperm acrosome evaluation parameters-including spontaneous AR rate, AR after calcium ionophore A23187 challenge (ARIC) rate, and modified Kennedy acrosin activity-can predict fertilization outcomes in vitro and are correlated with male characteristics. A total of 485 eligible couples undergoing in vitro fertilization (IVF) therapy were included in two phases of this study. In a 'construction phase', three acrosome evaluation parameters were determined simultaneously in 132 cases, whereas in a 'validation phase', the spontaneous AR rate was determined in 353 cases. The results of the 'construction phase' revealed that the spontaneous AR rate was the only significant predictor of fertilization outcome (unadjusted odds ratio [OR] = 0.68, 95% confidence interval [CI]: 0.53-0.88, P =  0.003; adjusted OR = 0.64, 95% CI: 0.43-0.95, P =  0.03), and the cut-off value for total fertilization failure (TFF) prediction, determined by ROC curve analysis, was 9.91%; higher acrosin activity was shown to predict a higher fertilization rate only when patients were divided into groups (≥25 μIU/10⁶ spermatozoa, 14-25 μIU/10⁶ spermatozoa, <14 μIU/10⁶ spermatozoa). The spontaneous AR rate was negatively correlated with sperm motility, forward progression motility, and normal morphology; modified Kennedy acrosin activity was positively correlated with normal morphology; and the ARIC rate was not correlated with any of the male characteristics. A similar result was obtained for the spontaneous AR rate in the 'validation phase', and the cut-off value in predicting TFF was calibrated for 9.52%. Clinically, patients can voluntarily choose spontaneous AR rate alone or in combination with modified Kennedy acrosin activity to predict TFF, and early rescue intracytoplasmic sperm injection (ICSI), half ICSI, or full ICSI should be considered in advance for men with spontaneous AR rates ≥9.52% or spontaneous AR rates ≥9.52% and AE activities <25 μIU/10⁶ spermatozoa.

Developmental potential of embryos from cycles containing oocytes with severe ovoid zona pellucida

The purpose of this study was to determine the incidence of oocytes with severe ovoid zona pellucida (ZP), investigate the development potential of their sibling oocytes and the clinical outcomes from affected cycles. The data were collected from our medical records. Cycles having at least one oocyte with severe ovoid ZP were defined as the 'severe ovoid group', cycles having at least one oocyte with mild ovoid ZP were defined as the 'mild ovoid group', whereas cycles without oocytes with ovoid ZPs were defined as the 'control group' (n = 150 for each group). The results showed that sibling embryos in the 'severe ovoid group' were characterized by delayed development and lower available embryo rate. The implantation, clinical pregnancy and live birth rates in this group were also significantly lower than that in the other two groups. There were five cycles in which only one embryo with severe ovoid ZP was transferred and two healthy babies were born. The mild ovoid group showed comparable embryo development and clinical outcomes compared with the control group. This study suggests that cycles containing oocytes with severe ovoid ZPs had delayed embryo development, lower available embryo rate, compromised implantation, clinical pregnancy and live birth rates.

Comparison of the Developmental Potential and Clinical Results of In Vivo Matured Oocytes Cryopreserved with Different Vitrification Media

Background:

Oocyte vitrification is widely used throughout the world, but its clinical efficacy is inconsistent and depends on the vitrification media. This study compared the developmental potential and clinical results of in vivo matured oocytes cryopreserved with different vitrification media.

Methods:

This retrospective study involved vitrified-warmed oocytes at one in vitro fertilization laboratory. Vitrification media kits comprised the MC kit (ethylene glycol [EG] plus 1,2-propanediol [PROH]), the KT kit (EG plus dimethyl sulphoxide [DMSO]), and the Modified kit (EG plus DMSO and PROH kit). Rates of oocyte survival and subsequent developmental potential were recorded and analyzed. The t-test and the Chi-square test were used to evaluate each method's efficacy.

Results:

Oocyte survival rate was significantly higher for the Modified kit (92.0%) than for the MC kit (88.2%) (P < 0.05) and the KT kit (77.3%) (P < 0.001). The rate of high-quality embryo development in the Modified kit group (35.8%) was significantly higher than in the MC kit group (29.0%) and the KT kit group (28.3%) (P < 0.001). No significant differences were observed in the clinical pregnancy and implantation rates among the MC, KT, and Modified kit groups (37.2% vs. 30.2% vs. 39.6%; 21.9% vs. 18.8% vs. 27.4%, respectively) (P > 0.05). The high-quality embryo rate per warmed oocyte was significantly higher (23.4%) in the Modified kit group than in the other groups (P < 0.001). The embryo utilization and live birth rates per warmed oocyte were the highest in the Modified kit group, but not significantly (P > 0.05).

Conclusions:

Modified vitrification media are efficient for oocyte vitrification and, with further verification, may be able to replace commercially available media in future clinical applications.