Oocyte dysmorphism is not associated with aneuploidy in the developing embryo

Dual-Activated H2O2-Responsive AIE Probes for Oocyte Quality Assessment

Nonobstructive azoospermia (NOA) is an important cause of infertility, and intracytoplasmic sperm injection (ICSI) is the mainstay of treatment for these patients. In cases where a sufficient number of sperm (usually 1-2) is not available, the selection of oocytes for ICSI is a difficult problem that must be solved. Here, we constructed a dual-activated oxidative stress-responsive AIE probe, b-PyTPA. The strong donor-acceptor configuration of b-PyTPA leads to twisted intramolecular charge transfer (TICT) effect that quenches the fluorescence of the probe, however, H2O2 would specifically remove the boronatebenzyl unit and release a much weaker acceptor, which inhibits TICT and restores the fluorescence. In addition, the presence of a pyridine salt makes b-PyTPA more hydrophilic, whereas removal of the pyridine salt increases the hydrophobicity of PyTPA, which triggers aggregation and further enhances fluorescence. Thus, the higher the intracellular level of oxidative stress, the stronger the fluorescence. In vitro, this dual-activated fluorescent probe is capable of accurately detecting senescent cells (high oxidative stress). More importantly, b-PyTPA was able to characterize senescent oocytes, as assessed by the level of oxidative stress. It is also possible to identify high quality oocytes from those obtained for subsequent ICSI. In conclusion, this dual-activated oxidative stress-assessment probe enables the quality assessment of oocytes and has potential application in ICSI.

Different occurrence rates of centrally located cytoplasmic granulation in one cohort oocytes show distinctive embryo competence and clinical outcomes

Centrally located cytoplasmic granulation (central granulation) is a common cytoplasmic dysmorphism in human oocytes retrieved after controlled ovarian hyperstimulation (COH). In order to achieve a better understanding of its formation and effects on clinical outcomes, we retrospectively analyzed 422 ICSI treatment cycles. Three groups of patients were classified according to the ratio of central granulation occurrence in one egg cohort, as partial granulation, all granulation and control groups. The partial granulation group had a significantly lower BMI and higher AMH level compared to the control or all granulation groups. Consistent with these distinctive features in the partial granulation group, fertilization and blastocyst formation rates were reduced significantly in the partial granulation group but not in the all granulation group. Furthermore, the clinical outcomes in fresh embryo transfer cycles were dramatically reduced in the partial granulation group compared with the control group. However, in FET cycles, all three clinical outcomes were significantly reduced in the all granulation group but not in the partial granulation group. We propose that partial granulation may reflect a specific population of patients, and that the central granulation structure is sensitive to cryopreservation.

Does morphological assessment predict oocyte developmental competence? A systematic review and proposed score

PURPOSE

Does existing scientific literature suggest an impact of oocyte dysmorphisms on biological or clinical outcomes of assisted reproduction treatments?

METHODS

Studies of interest were selected from an initial cohort of 6651 potentially relevant records retrieved. PubMed was systematically searched for peer-reviewed original papers and reviews identified by keywords and medical subject heading (MeSH) terms. The most relevant publications were critically evaluated to identify criteria for oocyte morphological evaluation and IVF outcomes. For each morphological abnormality, we generated an oocyte literature score (OLS) through the following procedure: (a) papers showing a negative, absence of, or positive correlation between a given abnormality and IVF outcome were scored 1, 0, and - 1, respectively; (b) the sum of these scores was expressed as a fraction of all analyzed papers; (c) the obtained fraction was multiplied by 10 and converted into decimal number.

RESULT

We identified eleven different dysmorphisms, of which six were extracytoplasmic (COC, zona pellucida, perivitelline space, polar body 1, shape, giant size) and five intracytoplasmic (vacuoles, refractile bodies, SER clusters, granularity, color). Among the extracytoplasmic dysmorphisms, abnormal morphology of the COC generated an OLS of 8.33, indicating a large prevalence (5/6) of studies associated with a negative outcome. Three intracytoplasmic dysmorphisms (vacuoles, SER clusters, and granularity) produced OLS of 7.14, 7.78, and 6.25, respectively, suggestive of a majority of studies reporting a negative outcome.

CONCLUSION

COC morphology, vacuoles, SER clusters, and granularity produced OLS suggestive of a prevalence of studies reporting a negative outcome.

Human Oocyte Morphology and Outcomes of Infertility Treatment: a Systematic Review

Oocyte morphology assessment is easy to implement in any laboratory with possible quality grading prior to fertilization. At present, comprehensive oocyte morphology scoring is not performed as a routine procedure. However, it may augment chances for successful treatment outcomes if a correlation with certain dysmorphisms can be proven. In order to determine a correlation between oocyte morphology and treatment outcome, we performed a systematic search in PubMed and Cochrane Controlled Trials Register following PRISMA guidelines. A total of 52 articles out of 6,755 search results met the inclusion criteria. Dark colour of the cytoplasm (observed with an incidence rate of 7%), homogeneous granularity of the cytoplasm (19%) and ovoid shape of oocytes (7%) appeared to have no influence on treatment outcome. Abnormalities such as refractile bodies (10%), fragmented first polar body (37%), dark zona pellucida (9%), enlarged perivitelline space (18%) and debris in it (21%) are likely to affect the treatment outcome to some extent. Finally, cytoplasmic vacuoles (4%), centrally located cytoplasmic granularity (12%) and clusters of smooth endoplasmic reticulum (4%) negatively impact infertility treatment outcomes. Nonetheless, morphological assessment is informative rather than predictive. Adding oocyte morphology to the artificial intelligence (AI)-driven selection process may improve the precision of the algorithms. Oocyte morphology assessment can be especially useful in oocyte donation cycles, during oocyte freezing for fertility preservation and finally, objective oocyte scoring can be important in cases of very poor treatment outcome as a tool for explanation of results to the patient.

Follicular GH and IGF1 Levels Are Associated With Oocyte Cohort Quality: A Pilot Study

INTRODUCTION

Oocyte quality contributes to the development of an optimal embryo and thus a successful pregnancy. The objective of this study was to analyse the association between oocyte cohort quality and the follicular levels of growth hormone (GH), insulin-like growth factor 1 (IGF1), 25-hydroxy vitamin D (25OHD), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) and antithyroid antibodies, as a function of intracytoplasmic sperm injection (ICSI) outcomes.

MATERIAL AND METHODS

We conducted a prospective comparative pilot study from January 2013 to December 2017. 59 ICSI cycles constituted an abnormal oocyte cohort (n=34 cycles, in which more than 50% of oocytes presented at least one morphological abnormality) and a normal oocyte cohort (n=25 cycles, in which 50% or less of the oocytes presented at least one morphological abnormality). GH, IGF1, 25OHD, TSH, fT3, fT4 and antithyroid antibodies were measured in follicular fluid.

RESULTS

The fertilisation rate was lower in the abnormal oocyte cohort (65.5% vs. 80%, respectively, p=0.012). Oocytes' proportion with at least one abnormality was 79.4% in the abnormal oocyte cohort and 29.0% in the normal oocyte cohort. The mean number of morphological abnormalities per oocyte was significantly higher in the abnormal oocyte cohort. The follicular levels of GH (4.98 vs. 2.75 mIU/L, respectively; p <0.01) and IGF1 (72.1 vs. 54.2 ng/mL, respectively; p=0.05) were higher in the normal oocyte cohort. There was no association with follicular levels of TSH, fT3, fT4, antithyroid antibodies, or 25OHD.

CONCLUSION

Oocyte cohort quality appears to be associated with follicular levels of GH and IGF1.

Ovarian Endometrioma Negatively Impacts Oocyte Quality and Quantity But Not Pregnancy Outcomes in Women Undergoing IVF/ICSI Treatment: A Retrospective Cohort Study

PURPOSE

To determine the impact of ovarian endometrioma per se on in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) outcomes.

METHODS

This retrospective study was conducted using two groups. The endometrioma group consisted of 862 women with infertility who had ovarian endometriomas and underwent their first ovarian stimulation for IVF/ICSI treatment between January 2011 to December 2019 at a public university hospital. A non-endometrioma comparison group, comprising 862 women with other infertility factors, was matched according to maternal age, body mass index (BMI), and infertility duration. Ovarian reserve and response and IVF/ICSI and pregnancy outcomes between the two groups were analyzed. Multivariate logistic regression (MLR) analysis was conducted on the basis of clinical covariates assessed for their association with live birth.

RESULTS

The results showed that significantly lower antral follicle count (AFC), anti-Müllerian hormone (AMH), ovarian sensitivity index (OSI), oocyte maturation and fertilization rates, blastocyst rate, number of oocytes retrieved, and available embryos were found in women with endometrioma compared with the control, respectively (P < 0.05). The cumulative live birth rate per patient in women with endometrioma was lower than that of women without endometrioma (39.32% vs. 46.87%, P = 0.002). In women with endometrioma, those who underwent surgical intervention prior to IVF/ICSI treatment had higher maturation (86.03% vs. 83.42%, P = 0.003), fertilization (78.16% vs. 74.93%, P = 0.004), and top-quality embryo rates (42.94% vs. 39.93%, P = 0.097) but had fewer oocytes retrieved (8.01 ± 5.70 vs. 9.12 ± 6.69, P = 0.013) than women without surgery. However, live birth rates were comparable between women with endometrioma and women in the control group, regardless of whether they had a prior history of ovarian surgery. MLR analysis showed no correlation between endometrioma per se and live birth after being adjusted for number of top-quality embryos transferred and stage of embryo transfer.

CONCLUSIONS

The data from this study supported the conclusion that ovarian endometrioma negatively impacts oocyte quality and quantity, but not overall pregnancy outcomes, in women undergoing IVF/ICSI treatment. Endometrioma lowers the cumulative live birth rate by decreasing the number of embryos. Surgical excision of endometrioma prior to IVF/ICSI can partly improve oocyte maturation and fertilization rates but not pregnancy outcomes.

The impact of endometrioma on in vitro fertilisation/intra-cytoplasmic injection IVF/ICSI reproductive outcomes: a systematic review and meta-analysis

Background

Assisted reproductive technologies (ART) such as in vitro fertilisation (IVF) and intra-cytoplasmic sperm injection (ICSI) are often used to aid fertility in women with endometrioma; however, the implications of endometrioma on ART are unresolved.

Objective

To determine the effect of endometrioma on reproductive outcomes in women undergoing IVF or ICSI.

Methods

A systematic review and meta-analysis was conducted to identify articles examining women who had endometrioma and had undergone IVF or ICSI. Electronic searches were performed in PubMed, BIOSIS and MEDLINE up to September 2019. The primary outcome was live birth rate (LBR). Secondary outcomes included clinical pregnancy rate (CPR), implantation rate (IR), number of oocytes retrieved, number of metaphase II (MII) oocytes retrieved, number of embryos and top-quality embryos and the duration of gonadotrophin stimulation and dose.

Results

Eight studies were included. Where significant heterogeneity between studies was identified, a random-effects model was used. The number of oocytes (weighted means difference; WMD-2.25; 95% CI 3.43 to − 1.06, p = 0.0002) and the number of MII oocytes retrieved (WMD-4.64; 95% CI 5.65 to − 3.63, p < 0.00001) were significantly lower in women with endometrioma versus controls. All other outcomes, including gonadotrophin dose and duration, the total number of embryos, high-quality embryos, CPR, IR and LBR were similar in women with and without endometrioma.

Conclusion

Even though women with endometriomas had a reduced number of oocytes and MII oocytes retrieved when compared to women without, no other differences in reproductive outcomes were identified. This implies that IVF/ICSI is a beneficial ART approach for women with endometrioma.

Selection of competent oocytes by morphological criteria for assisted reproductive technologies

Invasive and noninvasive methods are commonly used to select developmentally competent oocytes that can improve the take-home baby rates in assisted reproductive technology (ART) centers. One of the noninvasive methods conventionally utilized to determine competent oocytes is the morphological analysis of cumulus complex, first polar body, zona pellucida, perivitelline space, meiotic spindle, and ooplasm. Successful fertilization, early embryo development, uterine implantation, and healthy pregnancy depend on the quality of oocytes, and morphological evaluation is one of the options used to predict quality levels. In this review, the morphological criteria being utilized in certain ART centers are comprehensively evaluated with special references to their predictive values and potential contributions to selecting high-quality oocytes.

Nutritional impact on gene expression and competence of oocytes used to support embryo development and livebirth by cloning procedures in goats

Changes in the nutritional plan have been shown to affect oocyte quality, crucial to oocyte donors animals used in cloning. This study aimed to evaluate the impact of diets with increasing nutritional levels (maintenance diet=M; 1.3M; 1.6M; 1.9M) fed to goats for four weeks on follicular fluid composition, gene expression and oocyte competence used to cloning in goats. Donor females were superovulated for the retrieval of matured oocytes and physical measurements reported. After four weeks, groups receiving diets above maintenance increased thickness of subcutaneous adipose tissue and body weight, with higher values in 1.9M Group (P<0.05). Treatments did not affect follicular density, number of aspirated follicles, retrieved and matured oocytes. Animals from 1.3M group had lower (P<0.05) maturation rate (44.0%) and number of viable oocytes (65.3%) than M (68.8%) and 1.9M (76.0%). Follicular fluid glucose concentrations increased with nutritional levels (P=0.010), with a difference (P<0.05) between groups 1.9M (11.4±2.6mg/dL) and M (2.6±0.5mg/dL). The diet did not affect the expression of GDF9, BMP15, and BAX genes in oocytes, but BCL2 and apoptotic index were significantly higher (P<0.05) in the 1.3M and 1.6M groups than the other groups. Following the transfer of cloned embryos, one fetus was born live of a twin pregnancy in the 1.9M Group. The association between energy intake and oocyte quality suggests better nutritional use by oocytes when the maximum flow was used (1.9M), but the optimal feeding level in cloning still needs refinement.

Impact of oocytes with CLCG on ICSI outcomes and their potential relation to pesticide exposure

BACKGROUND

Oocyte quality is a key limiting factor in female fertility which is primarily reflected in morphological features. Centrally located cytoplasm granulation (CLCG) is one type of cytoplasmic dimorphism exhibited by oocytes that could be linked to pesticide exposure with a significant risk of decreased ICSI outcomes.

METHODS

This retrospective study included 633 women who were part of an intracytoplasmic spermatozoa injection (ICSI) program between 2009 and 2011. The participants lived in the Picardy region of France and had been exposed to pesticides. The participants were divided in two groups based on prevalence of oocytes with CLCG (LCLCG [n = 83]: low prevalence of oocytes with CLCG under 25%. HCLCG [n = 68]: high prevalence of CLCG over 75%). The embryological and clinical outcomes were analysed for both groups and were calculated using the difference between the two values.

RESULTS

Results for couples with HCLCG compared to LCLCG showed a decrease in embryo cleavage, ongoing pregnancy, and live birth rates (82%, 14%, 13% vs 99%, 32%, 30%, respectively).The early miscarriage rate was increased (47% vs 11%), with an OR of 3.1 (95%CI [2.1-4.1]). Due to high pesticide exposure (over 3000 g/ha), there is a higher risk of a resulting disturbed oocyte cohort with a high prevalence of CLCG over 75%.

CONCLUSION

The high prevalence of oocytes with CLCG over 75% has a negative effect on embryos and the general ICSI clinical outcomes. Furthermore, a putative association between pesticide exposure and risk of CLCG was identified, justifying the need for further research and a potential need to find alternative assisted reproductive technologies for these couples.

TRIAL REGISTRATION

Tabacfertimasc. ID number: ID2011-A00634-37 ; registered 2011/2/8.

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.

Ultrastructural and cytogenetic analyses of mature human oocyte dysmorphisms with respect to clinical outcomes

PURPOSE

The study aimed to describe the ultrastructure of two human mature oocyte intracytoplasmic dysmorphisms, the bull-eye inclusion and the granular vacuole, with evaluation of clinical outcomes after intracytoplasmic sperm injection (ICSI) treatment.

METHODS

We retrospectively evaluated 4099 consecutive ICSI cycles during the period 2003-2013. Three groups were compared: controls, those with a bulls-eye inclusion, and those with granular vacuoles. Oocyte dysmorphisms were evaluated by transmission electron microscopy and in situ fluorescence hybridization (FISH). Detailed data on demographic and stimulation characteristics, as well as on embryological, clinical, and newborn outcomes, are fully presented.

RESULTS

The bull-eye inclusion is a prominent smooth round structure containing trapped vesicles, being surrounded by lipid droplets. The presence of this dysmorphism in the oocyte cohort had no clinical impact except when transferred embryos were exclusively derived from dysmorphism oocytes. The granular vacuole is delimited by a discontinuous double membrane and contains lipid droplets and vesicles. As FISH analysis revealed the presence of chromosomes, they probably represent pyknotic nuclei. The presence of this dysmorphism in the oocyte cohort had no clinical impact except when at least one transferred embryo was derived from dimorphic oocytes.

CONCLUSIONS

Poor clinical outcomes were observed with transfer of embryos derived from dysmorphism oocytes, although without causing gestation or newborn problems. The bull-eye inclusion and granular vacuoles may thus be new prognostic factors for clinical outcomes.

Effect of oocyte dysmorphisms on intracytoplasmic sperm injection cycle outcomes in normal ovarian responders

AIM

The aim of this study was to identify the influence of oocyte dysmorphisms on clinical outcomes after intracytoplasmic sperm injection cycle in normal responders.

MATERIAL AND METHODS

In the prospective study, morphology of 1999 metaphase II oocytes retrieved from 316 intracytoplasmic sperm injection cycles was evaluated from March 2011 to March 2013 at Royan Institute. Controlled ovarian stimulation was performed by long standard agonist protocol. Oocyte morphology was assessed before sperm injection by one embryologist. The associations between fertilization rate, embryo quality and the independent variables were analyzed using odds ratio (OR) calculated with unconditional logistic regression test.

RESULTS

From all retrieved oocytes, 1543 (77.1%) showed at least one morphologic aberration. Presence of cytoplasmic vacuoles and high cytoplasmic viscosity were associated with a significant decrease in the fertilization rate (OR: 0.5; P = 0.004 and OR: 0.6; P = 0.03, respectively). The results showed that oocyte morphology did not affect embryo quality. The number of gonadotrophin injections used showed a direct relation with presence of large perivitelline space. No significant difference was observed among four groups (women with total normal morphologic oocytes [group 1], women with total extracytoplasmic dysmorphic oocytes [group 2], women with total cytoplasmic dysmorphic oocytes [group 3] and women with total oocytes containing multiple dysmorphic features [group 4]) in terms of implantation and clinical pregnancy rates.

CONCLUSIONS

Metaphase II oocyte morphology had minor impacts on fertilization rate, pronuclear morphology and embryo quality in women with normal ovarian response.

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.

Health outcomes of children born after IVF/ICSI: a review of current expert opinion and literature

The Sixth Evian Annual Reproduction (EVAR) Workshop Group Meeting was held to evaluate the impact of IVF/intracytoplasmic sperm injection on the health of assisted-conception children. Epidemiologists, reproductive endocrinologists, embryologists and geneticists presented data from published literature and ongoing research on the incidence of genetic and epigenetic abnormalities and congenital malformations in assisted-conception versus naturally conceived children to reach a consensus on the reasons for potential differences in outcomes between these two groups. IVF-conceived children have lower birthweights and higher peripheral fat, blood pressure and fasting glucose concentrations than controls. Growth, development and cognitive function in assisted-conception children are similar to controls. The absolute risk of imprinting disorders after assisted reproduction is less than 1%. A direct link between assisted reproduction and health-related outcomes in assisted-conception children could not be established. Women undergoing assisted reproduction are often older, increasing the chances of obtaining abnormal gametes that may cause deviations in outcomes between assisted-conception and naturally conceived children. However, after taking into account these factors, it is not clear to what extent poorer outcomes are due to the assisted reproduction procedures themselves. Large-scale, multicentre, prospective epidemiological studies are needed to investigate this further and to confirm long-term health consequences in assisted-conception children. Assisted reproduction treatment is a general term used to describe methods of achieving pregnancy by artificial means and includes IVF and sperm implantation. The effect of assisted reproduction treatment on the health of children born using these artificial methods is not fully understood. In April 2011, fertility research experts met to give presentations based on research in this area and to look carefully at the evidence for the effects of assisted reproduction treatment on children's health. The purpose of this review was to reach an agreement on whether there are differences in the health of assisted-conception children with naturally conceived children. The researchers discovered no increased risk in birth defects in assisted-conception children compared with naturally conceived children. They found that IVF-conceived children have lower birth weights and higher fat under the skin, higher blood pressure and higher fasting glucose concentrations than naturally conceived children; however, growth, development and cognitive function are similar between groups. A very low risk of disorders of genetic control was observed in assisted-conception children. Overall, there did not appear to be a direct link between assisted reproduction treatment and children's health. The researchers concluded that the cause of some differences in the health of children conceived using assisted reproduction treatment may be due to the age of the woman receiving treatment. Large-scale, research studies are needed to study the long-term health of children conceived using assisted reproduction treatment.

Polar body fragmentation in IVM oocytes is associated with impaired fertilization and embryo development

PURPOSE

The significance of finding a fragmented first polar body in an oocyte prepared for ICSI is controversial with most recent publications suggesting that it is not prognostic for oocyte fertilization or embryo development. Our purpose was to look at this question in the context of oocytes not stimulated for conventional IVF.

METHODS

Oocytes obtained for IVM and obtained from follicles at most 12 mm in diameter were evaluated for their polar body morphology soon after they entered metaphase II when they were denuded in preparation for ICSI. Records were evaluated retrospectively for the fertilization rate and the embryo growth rate (cell number) on each day of development for embryos with normal appearing polar bodies or fragmented polar bodies, but no other cytoplasmic dysmorphisms.

RESULTS

Oocytes with fragmented polar bodies were significantly less likely to fertilize than oocytes with normal appearing polar bodies (p < 0.0001). Embryos which developed from oocytes with fragmented polar bodies had significantly impaired growth compared to embryos that developed from oocytes with normal appearing polar bodies (p = 0.0328).

CONCLUSIONS

Fragmented polar bodies likely reflect cytoplasmic incompetence.

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

PURPOSE

To clarify if birefringent structures of human oocytes and embryos, measurable by polarized light microscopy, have any value in predicting the chance of pregnancy in human in vitro fertilization and may halp to identify the most competent oocytes and embryos.

METHODS

The inner layer of the zona pellucida (IL-ZP) and the meiotic spindle (MS) were analyzed by polarized light microscopy in 258 oocytes and in the 209 embryos deriving from them. Data obtained from 102 ICSI cycles with conception were compared with those obtained in 156 cycles without conception. The retardance and area of the IL-ZP, as well as the retardance, length of the major axis, and area of the MS were measured. Furthermore, polarized light microscopy parameters were related to the embryo morphological score by multiple regression analysis.

RESULT(S)

The mean area of the IL-ZP of both oocytes and embryos was significantly lower in conception than in non-conception cycles (p = 0.0001 for oocytes and p = 0.002 for embryos). The area of the IL-ZP in embryos was significantly, inversely related to the embryo morphological score (p = 0.011). The area, the major axis length and the retarcance of the MS, as well as the retardance of the IL-ZP in oocytes and embryos were comparable in conception and non-conception cycles.

CONCLUSION

The area of the IL-ZP of the human oocytes may represent a marker of oocyte competence, as oocytes with a low IL-ZP area are more frequently obtained in conception cycles. When measured in embryos, a low IL-ZP area identifies embryos with a high chance of implantation.

GnRH agonist versus GnRH antagonist in assisted reproduction cycles: oocyte morphology

BACKGROUND

The selection of developmentally competent human gametes may increase the efficiency of assisted reproduction. Spermatozoa and oocytes are usually assessed according to morphological criteria. Oocyte morphology can be affected by the age, genetic characteristics, and factors related to controlled ovarian stimulation. However, there is a lack of evidence in the literature concerning the effect of gonadotropin-releasing hormone (GnRH) analogues, either agonists or antagonists, on oocyte morphology. The aim of this randomized study was to investigate whether the prevalence of oocyte dysmorphism is influenced by the type of pituitary suppression used in ovarian stimulation.

METHODS

A total of 64 patients in the first intracytoplasmic sperm injection (ICSI) cycle were prospectively randomized to receive treatment with either a GnRH agonist with a long-term protocol (n: 32) or a GnRH antagonist with a multi-dose protocol (n: 32). Before being subjected to ICSI, the oocytes at metaphase II from both groups were morphologically analyzed under an inverted light microscope at 400x magnification. The oocytes were classified as follows: normal or with cytoplasmic dysmorphism, extracytoplasmic dysmorphism, or both. The number of dysmorphic oocytes per total number of oocytes was analyzed.

RESULTS

Out of a total of 681 oocytes, 189 (27.8%) were morphologically normal, 220 (32.3%) showed cytoplasmic dysmorphism, 124 (18.2%) showed extracytoplasmic alterations, and 148 (21.7%) exhibited both types of dysmorphism. No significant difference in oocyte dysmorphism was observed between the agonist- and antagonist-treated groups (P>0.05). Analysis for each dysmorphism revealed that the most common conditions were alterations in polar body shape (31.3%) and the presence of diffuse cytoplasmic granulations (22.8%), refractile bodies (18.5%) and central cytoplasmic granulations (13.6%). There was no significant difference among individual oocyte dysmorphisms in the agonist- and antagonist-treated groups (P>0.05).

CONCLUSIONS

Our randomized data indicate that in terms of the quality of oocyte morphology, there is no difference between the antagonist multi-dose protocol and the long-term agonist protocol. If a GnRH analogue used for pituitary suppression in IVF cycles influences the prevalence of oocyte dysmorphisms, there does not appear to be a difference between the use of an agonist as opposed to an antagonist.

Predictive value of oocyte morphology in human IVF: a systematic review of the literature

BACKGROUND

Non-invasive selection of developmentally competent human oocytes may increase the overall efficiency of human assisted reproduction and is regarded as crucial in countries where legal, social or religious factors restrict the production of supernumerary embryos. The purpose of this study was to summarize the predictive value for IVF success of morphological features of the oocyte that can be obtained by light or polarized microscopic investigations.

METHODS

Studies about oocyte morphology and IVF/ICSI outcomes were identified by using a systematic literature search.

RESULTS

Fifty relevant articles were identified: 33 analysed a single feature, 9 observed multiple features and investigated the effect of these features individually, 8 summarized the effect of individual features. Investigated structures were the following: meiotic spindle (15 papers), zona pellucida (15 papers), vacuoles or refractile bodies (14 papers), polar body shape (12 papers), oocyte shape (10 papers), dark cytoplasm or diffuse granulation (12 papers), perivitelline space (11 papers), central cytoplasmic granulation (8 papers), cumulus–oocyte complex (6 papers) and cytoplasm viscosity and membrane resistance characteristics (2 papers). None of these features were unanimously evaluated to have prognostic value for further developmental competence of oocytes.

CONCLUSIONS

No clear tendency in recent publications to a general increase in predictive value of morphological features was found. These contradicting data underline the importance of more intensive and coordinated research to reach a consensus and fully exploit the predictive potential of morphological examination of human oocytes.

Metaphase II human oocyte morphology: contributing factors and effects on fertilization potential and embryo developmental ability in ICSI cycles

Morphologic abnormalities in the oocyte are relevant for determining its developmental fate and could be related to controlled ovarian stimulation protocols and ovarian response. The contributing factors of oocyte dysmorphism incidence and its effects on fertilization potential and embryo development are the object of discussion in this study.

Severe cytoplasmic abnormalities of the oocyte decrease cryosurvival and subsequent embryonic development of cryopreserved embryos

BACKGROUND

Abnormalities of oocyte morphology affect embryo quality and viability. Whether morphological abnormalities of the oocyte influence cryosurvival and further development of derived embryos is not known. The aim of this study was to compare cryosurvival and progression to the blastocyst stage of frozen-thawed embryos derived from normal and abnormal oocytes.

METHODS

A total of 5292 Grade 1 and 2 embryos from 964 women were frozen, thawed and subsequently cultured up to the blastocyst stage. The study was performed on excess embryos from patients who did not opt for cryopreservation. Cryosurvival, progression to the blastocyst stage and hatching were correlated with morphological characteristics of the oocytes that embryos were derived from.

RESULTS

Presence of a cytoplasmic abnormality of the oocyte significantly decreased cryosurvival. This detrimental effect was more pronounced in embryos derived from oocytes with vacuolar cytoplasm or with central granulation. Furthermore, these embryos did not have the potential to develop into good quality blastocysts or reach the hatching stage. On the other hand, presence of a single extracytoplasmic abnormality of the oocyte did not affect cryosurvival and the potential to develop into good quality blastocysts. Grade 2 embryos derived from oocytes with irregular shape or a large perivitelline space had decreased cryosurvival. However when these embryos survived cryopreservation, their potential to develop good quality blastocysts or to reach hatching stage was unaffected.

CONCLUSIONS

Embryos derived from oocytes with vacuolar cytoplasm or central granulation do not seem to bear the potential to develop good quality blastocysts or to reach hatching stage after cryopreservation. The presence of extracytoplasmic abnormalities alone does not affect blastocyst development despite decreasing cryosurvival.