Evaluation Of Oocyte Quality Research Articles

Correlation between oocyte morphology and the embryo aneuploidy rate in IVF cycles

Aneuploidy is the main genetic cause of miscarriages and congenital birth defects following both natural conception and in vitro fertilization (IVF). The oocyte aneuploidy rate varies over a wide range, but there is a close correlation between advancing maternal age and the increasing aneuploidy rate. Controlled ovarian stimulation additionally complicates this problem because it leads to the maturation of oocytes that would naturally undergo apoptosis. A large proportion of oocytes recovered from exogenous gonadotropin-stimulated cycles exhibit different morphological abnormalities (dysmorphisms). The purpose of the study was to evaluate the aneuploidy rates of chromosomes 13, 18, 21, X and Y in embryos from patients with different oocyte morphotypes. Materials and methods: This prospective study included 84 patients treated with IVF at a single academic center. The patients were divided into the following groups: group 1 consisted of women with cytoplasmic dysmorphisms (n = 28), group 2 consisted of women with extracytoplasmic dysmorphisms (n = 28), and group 3 consisted of women with morphologically normal oocytes (n = 28). One blastomere from each embryo was analyzed for aneuploidies of chromosomes 13, 18, 21, X, and Y results. In total we sampled 368 embryos on day 3 (98 from group 1, 126 from group 2 and 144 from group 3). In group 1, there were 67 aneuploid embryos (68.4%); in group 2, there were 49 aneuploid embryos (38.9%); and in group 3, there were 45 (31.3%) (p < 0.0001). To identify the factors that influenced the appearance of aneuploidy in the embryo, we compared the groups with euploid (group A, n = 161) and aneuploid embryos (group B, n = 207). The aneuploidy rate was related to some of the female baseline characteristics, specifically, body mass index (BMI) and the basal AMH level. The women in group B were more likely to have histories of chlamydia infection. The summary dose of gonadotropins was higher in group B. Sperm quality (from the fertile or subfertile males) did not influence the embryo aneuploidy rate. The adjusted odds ratio (OR) for an aneuploid embryo in cases of cytoplasmic dysmorphisms was 3.6 (95% CI = 1.8; 7.2) after adjusting for the confounders. The adjusted OR for an aneuploid embryo in cases of extracytoplasmic dysmorphisms was 1.3 (95% CI = 0.7; 2.1) after considering the confounders. The highest percentage of aneuploid embryos occurred in the subgroup of oocytes with vacuoles (100%) followed by the oocytes with dark cytoplasm (73.1%), centrally located granular cytoplasm (66.7%) and SERc (65.2%) (Table 1). The most frequent type of aneuploidy was chromosomal polysomy. The prevalence of all of the types of polysomies was much higher in the group of women with cytoplasmic dysmorphisms. Discussion: Aneuploidies of the gametes are not only the limiting factors for human fertility but are also for the medical treatment of infertility. Morphological assessments of oocytes are the most common method for evaluating oocyte quality in routine practice. Oocyte dysmorphisms are correlated with impaired embryo quality and thus poor clinical outcomes, which may be related to high aneuploidy rates in oocytes with dysmorphisms. We recommend that woman with oocyte dysmorphisms, especially a centrally located granular cytoplasm, SERc and a dark cytoplasm, be subjected to additional genetic counseling to improve the effectiveness of IVF cycles and reduce the risk of giving birth to children with congenital defects.

Development of insulin resistance in dairy cows by 150 days of lactation does not alter oocyte quality in smaller follicles

The objective of this study was to test the hypothesis that high-producing dairy cows become increasingly resistant to insulin throughout lactation and that, consequently, oocyte quality is compromised. We used Holstein cows at 50 (51.5±3.7; n=30), 100 (102.3±9.4; n=30), and 150 (154.5±18.9; n=30) days in milk (DIM). We measured circulating insulin and glucose and performed a glucose tolerance test (GTT) after 5h of fasting. To evaluate oocyte quality, we performed ovum pickup on the day before the GTT (581 oocytes). We performed statistical analyses using the MIXED procedure of SAS. The model included the fixed effects of DIM, period, time, parity, and an interaction between DIM and time. We observed no difference in the GTT between groups for any variable related to circulating glucose (for example, glucose peak=203.3±7.2, 208.8±6.3, and 194.3±5.9mg/dL). However, various measures of circulating insulin were different in cows at 150 DIM compared with 50 or 100 DIM: higher basal insulin (8.8±0.9, 8.8±0.8, and 11.9±0.8 µIU/mL), peak insulin (61.9±6.2, 69.1±5.7, and 89.0±6.1 µIU/mL), delta maximum insulin (51.1±5.5, 59.4±5.0, and 73.5±5.4 µIU/mL), and area under the curve 5-60 (1,874.8±171.0, 2,189.5±157.8, and 2,610.5±174.0 µIU/mL × min). Nevertheless, we observed no difference among groups in the number of viable oocytes (3.2±0.7, 3.9±0.7, and 3.6±0.7 per cow per ovum pickup) or percentage of viable oocytes (49.3, 52.2, and 51.8%). Increased circulating insulin before and throughout the GTT in cows at 150 DIM indicates that cows develop increasing insulin resistance with increasing DIM; however, increased insulin resistance was not associated with a detectable alteration in the quality of oocytes aspirated from small and medium-sized follicles.

Developmental competence of mammalian oocytes-insights into molecular research and the promise of microfluidic technology: a review

Developmental competence of female gametes determines their maturation ability, successful fertilisation, and proper zygote formation. Oocyte quality may be assessed by expression profiling of several gene markers such as Cx43, TGFB, GDF9, BMP, Lox and Pdia5 that determine the biological features of oocytes. Conversely, several other extrinsic factors, including follicular size or heat shock may significantly influence oocyte quality and ability to grow and develop during folliculo- and oogenesis. However, using molecular methods for evaluation of oocyte quality often leads to destruction of an analysed cell. Therefore, there is an increased requirement to seek new non-invasive methods of oocyte-embryo quality assessment. Here we describe the Lab-on-Chip system based on microfluidic technology, which is the first parametric and objective device for evaluation of oocyte developmental competence using spectral images. In this review several extrinsic factors and molecular markers of oocyte developmental competence are discussed. Furthermore, based on our previous studies, we discuss the possibility of applying the spectrophotometric system (Lab-on-Chip) in both biomedical and reproductive research in domestic animals.

Relationship between diminished ovarian reserve and mitochondrial biogenesis in cumulus cells.

What part do mitochondria play in cases of diminished ovarian reserve (DOR)? Mitochondrial biogenesis in cumulus cells may be linked with impaired oocyte competence in patients with DOR. DOR, one of the causes of infertility even in young women, is characterized by the depletion of the ovarian pool associated with a decline in oocyte competence. Mitochondria, which play a role in oocyte quality, could be involved in the pathogenesis of DOR. The study of cumulus cells offers an interesting non-invasive approach for evaluating oocyte quality and the metabolic processes on which it depends. If mitochondrial dysfunction is involved in DOR, it is likely to have an impact on the functioning of cumulus cells. This is an observational study of 74 immature oocyte-cumulus complexes retrieved from 47 women undergoing in vitro fertilization with intracytoplasmic sperm injection at the University Hospital of Angers, France, from March 2013 to March 2014. The women were divided into two groups: one group included 26 women with DOR, and the other, which included 21 women with a normal ovarian reserve (NOR), served as a control group. The oocyte mitochondrial content and the average mitochondrial content of the cumulus cells were assessed by mitochondrial (mt)DNA quantification using a quantitative real-time PCR technique. Microfluidic-based quantitative RT-PCR assays were used to quantify the expression of 13 genes involved in mitochondrial functions such as apoptosis and antioxidant activity or in mitochondrial biogenesis. We used orthogonal partial least-squares discriminant analysis (OPLS-DA) to distinguish between the DOR group and the NOR group of patients, and an OPLS model to predict the value of the oocyte mtDNA content that could be used as a critical marker of oocyte quality. The OPLS-DA model showed a good predictive capability (Q2 = 0.543). Using the variable importance in projection (VIP) metric we found three mitochondrial variables distinguishing the DOR group from the NOR group of patients, i.e. the oocyte mtDNA content (VIP = 0.92), the cumulus cell mtDNA content (VIP = 0.95) and the expression in cumulus cells of peroxisome proliferator-activated receptor γ coactivator 1 alpha (PPARGC-1A) (VIP = 1.10), all of which were lower in the DOR group than in the NOR group of patients. The OPLS model was able to satisfactorily predict the oocyte mtDNA content in only the NOR group of patients (Q2 = 0.506). We found four new variables positively linked to the oocyte mitochondrial mass, i.e. the cumulus cell mtDNA content (VIP = 1.19), and the expression in cumulus cells of three factors of mitochondrial biogenesis: polymerase gamma (POLG) (VIP = 2.13), optic atrophy 1 (OPA1) (VIP = 1.89) and the transcription factor associated with mitochondria (TFAM) (VIP = 1.32). This is a descriptive study. Because of ethical concerns in human clinical practice, this study has been performed only on immature oocytes and corresponding cumulus cells, which are usually discarded during in vitro fertilization procedures. Cumulus cells may govern mitochondrial biogenesis, creating an adequate oocyte mitochondrial pool to promote embryonic development. The alteration of this process in patients with DOR may account for the impairment of oocyte quality. This suggests that some mitochondrial characteristics of cumulus cells may serve as indicators of oocyte competence and that oocyte quality may be improved by products enhancing mitochondrial biogenesis. This work was supported by a grant from the University Hospital of Angers, France: 'Appel d'offre interne à la recherche 2014'. N/A.

Evaluation of oocyte quality and ovarian function in aged female cystine-glutamate transporter gene-deficient mice

Evaluation of oocyte quality and ovarian function in aged female cystine-glutamate transporter gene-deficient mice

Kit ligand and insulin-like growth factor I affect the in vitro development of ovine preantral follicles

We investigated the effect of KL and IGF-I, alone or in combination, on the in vitro survival, growth and antrum formation of sheep preantral follicles, and subsequent oocyte developmental competence. Preantral follicles ∼200μm were isolated and cultured for 18 days in basic medium (control) added or not by KL, IGF-I or both. Every six days follicular survival, growth and antrum formation was evaluated. At the end of the culture period, the oocytes underwent in vitro maturation (IVM) and their viability and chromatin configuration were assessed. To evaluate oocyte quality and its developmental competence, parthenogenetic activation and in vitro fertilization (IVF) of the oocytes recovered from in vitro grown preantral follicles were performed. Medium supplementation with KL improved follicular integrity and antrum formation. IGF-I promoted the increase in follicular diameter at the end of the in vitro culture when compared to control, but not differently from KL. Follicles cultured in the presence of KL presented the highest percentages of meiosis resumption (92.3%). Therefore, these oocytes were submitted to parthenogenetic activation and IVF resulting in a percentage of 35.6% of parthenotes and 23.1% of 2- or 4-cells embryos. Medium supplementation with KL results in increased rates of antrum formation, as well as in meiosis resumption, resulting in the production of embryos using parthenogenetic activation or IVF.

A methodological and functional proteomic approach of human follicular fluid en route for oocyte quality evaluation

Human follicular fluid (HFF) has been proven to contain biologically active molecules and proteins that may affect follicle growth and oocyte fertilization. Based on this concept, HFF proteomic characterization is having a significant impact in the delineation of a biomarkers' profile for oocyte quality estimation and, maybe, for in vitro fertilization (IVF) success improvement. Follicular fluid is characterized by a vast protein complexity and a broad dynamic range of protein abundances that hinder its analysis. In this study we determined a proper solubilization and resolution method of HFF in 2-DE, minimizing sample manipulation, protein loss, and experimental artifacts. According to our methodology some low-abundance proteins were detected and identified by MS. Identified proteins were then functionally cross-linked by a pathway analysis. The generated path highlighted the occurrence in HFF of a tight functional-network in which effectors and inhibitors control and balance a space- and time-dependent induction/inhibition of inflammation, coagulation, and ECM degradation/remodeling. Such fine modulation of enzymatic activities exerts a fundamental role in follicle development and in oocyte competence acquiring. Alpha-1-antitrypsin resulted in the core protein of the delineated net and we interestingly detected its differential incidence in FF and serum from two small cohorts of patients who underwent IVF. Human ovarian follicular fluid (HFF) is the in vivo microenvironment for oocyte during folliculogenesis. It contains biologically active molecules that may affect oocyte quality, fertilization, and embryo development. HFF is also one of the most abundant "waste product" in assisted reproduction. This makes HFF a readily accessible source of biomolecules for competence evaluation of collected oocytes. The methodological improvement we obtained in proteomics characterization of HFF lead to a wide overview on the functional correlation existing between several fluid components and on how their aberrant occurrence/activity may affect oocyte quality and ovulation.

Follicular-fluid anti-Mullerian hormone (FF AMH) is a plausible biochemical indicator of functional viability of oocyte in conventional in vitro fertilization (IVF) cycles

CONTEXT:Oocyte quality may be a governing factor in influencing in vitro fertilization (IVF) outcomes. However, morphological evaluation of oocyte quality is difficult in conventional IVF cycles. Follicular-fluid (FF), the site for oocyte growth and development, has not yet been sufficiently explored to obtain a marker indicative of oocyte quality. Anti-Mullerian hormone (AMH) is produced by granulosa cells of preantral and early-antral follicles and is released in FF.AIM:To investigate AMH as a biochemical indicator of functional viability/quality of oocyte produced in the FF micro-environmental milieu.SETTINGS AND DESIGN:Prospective study involving 132 cycles of conventional IVF-embryo transfer (ET) in infertile women.SUBJECTS AND METHODS:AMH concentration was estimated in pooled FF on day of oocyte pickup. Cycles were sorted into low and high groups according to median (50 th centile) values of measurement. Main outcome measure was oocyte viability, which included morphological assessment of oocyte quality, fertilization rate, clinical pregnancy, and implantation rates.STATISTICAL ANALYSIS:Graph-pad Prism 5 statistical package.RESULTS:Low FF AMH group shows significantly higher percentage of top-quality oocytes (65.08 ± 24.88 vs. 50.18 ± 25.01%, P =0.0126), fertilization (83.65 ± 18.38 vs. 75.78 ± 21.02%, P =0.0171), clinical pregnancy (57.57 vs. 16.67%, P >0.0001), and embryo implantation rates (29.79 vs. 7.69%, P >0.0001) compared to high FF AMH group. FF AMH shares an inverse correlation with FF E2 (Pearson r = −0.43, r2 = 0.18) and clinical pregnancy (Pearson r = −0.46, r2 = 0.21). Threshold value of FF AMH for pregnancy is >1.750 ng/mg protein.CONCLUSION:FF AMH is a plausible biochemical indicator of functional viability of oocyte in conventional IVF cycles.

Gene Expression Profiling of Human Oocytes Developed and MaturedIn VivoorIn Vitro

The quality of the human oocyte determines the success of fertilization and affects the consequent embryo development, pregnancy and birth; it therefore serves as a basis for human reproduction and fertility. The possibility to evaluate oocyte quality in the in vitro fertilization programme is very limited. The only criterion which is commonly used to evaluate oocyte quality is its morphology. There is a mass of oocytes in the in vitro fertilization programme which are not fertilized in spite of normal morphology. In the past, several attempts focused on oocyte gene expression profiling by different approaches. The results elucidated groups of genes related to the human oocyte. It was confirmed that some factors, such as oocyte in vitro maturation, are detectable at the molecular level of human oocytes and their polar bodies in terms of gene expression profile. Furthermore, the first genetic evaluations of oocyte-like cells developed in vitro from human stem cells of different origin were performed showing that these cells express some genes related to oocytes. All these findings provide some new knowledge and clearer insights into oocyte quality and oogenesis that might be introduced into clinical practice in the future.

Eight-Cell Parthenotes Originated From In Vitro Grown Sheep Preantral Follicles

We investigated the effect of the leukemia inhibitory factor (LIF) alone or in association with follicle-stimulating hormone (FSH) on the in vitro growth and antrum formation of sheep preantral follicles. To evaluate oocyte quality, parthenogenetic activation of the oocytes recovered from in vitro grown preantral follicles was performed. Preantral follicles >110 μm in diameter were isolated and cultured for 18 days in basic medium either alone (control) or supplemented with LIF (10 or 50 ng/mL) in the absence or presence of FSH. Every 6 days the follicular survival, growth, and antrum formation were evaluated. When compared to control (P < .05), antrum formation was increased in follicles cultured in the presence of LIF10 and FSH. At the end of the culture, the oocytes underwent in vitro maturation (IVM); their viability and chromatin configuration were assessed. Although IVM was not affect by the treatments (P > .05), the numerically highest maturation rates (29.63%) were obtained when follicles were cultured in 50 ng/mL LIF (LIF50). Therefore, their oocytes were submitted to parthenogenetic activation; from which 58.3% of the mature oocytes resulted in 8-cell stage parthenotes. In conclusion, although LIF10 + FSH increases antrum formation when compared to a nonsupplemented medium (minimum essential medium), oocytes from sheep preantral follicles are capable of growing and maturing in vitro independent of LIF addition to the medium, which resulted in the formation of 8-cell parthenotes.

Comparative evaluation of oocyte quality in stimulated-intrauterine insemination (IUI) to in vitro fertilization (IVF) conversion cycles vs conventional IVF cycles and its impact on pregnancy outcome

Conversion of high-response ovulation induction-IUI cycles to In vitro fertilization-embryo transfer (IVF-ET) is a valid option to reduce the risks of Ovarian Hyperstimulation Syndrome and high-order multiple pregnancy besides. The aim of our study was to analyze the oocyte quality and clinical pregnancy rate (CPR) in IUI to IVF converted cycles and compare it with matched IVF controls.

43 EFFECT OF VITRIFICATION AT GERMINAL VESICLE STAGE ON THE MITOCHONDRIAL AND CYTOSKELETAL INTEGRITY IN BOVINE OOCYTES

In the previous report, we demonstrated that bovine germinal vesicle (GV) stage oocytes vitrified using a nylon mesh holder showed an in vitro maturation rate to the metaphase II (MII) stage similar to that of fresh ones. However, cleavage and developmental rates of vitrified oocytes were low. Because mitochondria and the cytoskeleton are thought to have a central role in energy supply and cellular division in mammalian embryogenesis, it seems possible that alternation in their function in vitrified GV oocytes may contribute to subsequent lower cleavage and developmental rates. The oxygen consumption rate reflects the mitochondrial activity and its measurement may be an effective way for non-invasive evaluation of oocyte quality. In this study, to ascertain that altered mitochondrial functions and cytoskeleton may contribute to reduce the quality of oocytes after vitrification, we evaluated the distribution of active mitochondria and the cytoskeleton in vitrified oocytes. We also examined the relationship between oxygen consumption rate and the distribution of active mitochondria in vitrified oocytes. Bovine GV oocytes connected with cumulus cells were exposed to the cryoprotectant (EFS40) in a stepwise way and transferred onto a nylon mesh holder, followed by plunging them directly into liquid nitrogen. After warming, vitrified oocytes were allowed in vitro maturation. After denuding, matured oocytes were stained with a mitochondria-specific probe, rhodamine-123 and then oxygen consumption rate using an embryo respirometer (HV-403; Research Institute for Functional Peptides, Yamagata, Japan) was measured in each oocyte. According to morphological distribution of mitochondria, oocytes were classified as follows: type 1, uniform distribution; type 2, spotted distribution; and type 3, a weak fluorescence. The oxygen consumption rate of the fresh oocytes at the MII stage was significantly (P &lt; 0.05) higher than that of vitrified oocytes (5.24 and 4 × 1015 mol–1 s–1, respectively), although there was no difference between the fresh and vitrified groups at the GV stage (5.02 and 5.06 × 1015 mol–1 s–1, respectively). The oxygen consumption rates of type 1 oocytes in fresh and vitrified groups at the MII stage tended to be higher than those of type 2 and 3 oocytes (type 1, 5.29 and 5.27; type 2, 4.99 and 4.52; type 3, 4.77 and 4.48 × 1015 mol–1 s–1, respectively). In addition, the percentage of type 1 oocytes in the fresh group was significantly (P &lt; 0.05) higher than that in the vitrified group (59.4 and 34.3%, respectively). The matured oocytes also were stained with α-tubulin monoclonal antibody or F-phalloidin independently to examine the morphological status of microtubules or microfilament. The rates of oocytes with abnormal microtubules and microfilament in the vitrified group were 29.7 and 43.5%, respectively, showing higher rates compared with corresponding fresh oocytes (9.8%; P &lt; 0.05 and 25.0%; P = 0.21, respectively). These results suggested that the reduction of quality and subsequent developmental competence in vitrified oocytes might be related to damages of mitochondria and cytoskeleton.

The Transcriptome of a Human Polar Body Accurately Reflects Its Sibling Oocyte

Improved methods are needed to reliably and accurately evaluate oocyte quality prior to fertilization and transfer into the woman of human embryos created through in vitro fertilization (IVF). All oocytes that are retrieved and matured in culture are exposed to sperm with little in the way of evaluating the oocyte quality. Furthermore, embryos created through IVF are currently evaluated for developmental potential by morphology, a criterion lacking in quantitation and accuracy. With the recent successes in oocyte vitrification and storage, clear metrics are needed to determine oocyte quality prior to fertilizing. The first polar body (PB) is extruded from the oocyte before fertilization and can be biopsied without damaging the oocyte. Here, we tested the hypothesis that the PB transcriptome is representative of that of the oocyte. Polar body biopsy was performed on metaphase II (MII) oocytes followed by single-cell transcriptome analysis of the oocyte and its sibling PB. Over 12,700 unique mRNAs and miRNAs from the oocyte samples were compared with the 5,431 mRNAs recovered from the sibling PBs (5,256 shared mRNAs or 97%, including miRNAs). The results show that human PBs reflect the oocyte transcript profile and suggests that mRNA detection and quantification through high-throughput quantitative PCR could result in the first molecular diagnostic for gene expression in MII oocytes. This could allow for both oocyte ranking and embryo preferences in IVF applications.

Secretion profiles from in vitro cultured follicles, isolated from fresh prepubertal and adult mouse ovaries or frozen–thawed prepubertal mouse ovaries

In vitro folliculogenesis could be a new technology to produce mature oocytes from immature follicles that have been isolated from cryopreserved or fresh ovarian tissue. This technique could also be a tool for evaluation of oocyte quality and/or for determination of follicular parameters during follicular growth. Our objective was to characterize in mice the secretion profiles of follicles that had been isolated mechanically during in vitro follicular growth and in relation to the growth curve. Early preantral follicles from fresh prepubertal and adult mouse ovaries or frozen-thawed prepubertal mouse ovaries were cultured individually in microdrops under oil for 12 days. Each day, two perpendicular diameters of the follicles were measured. From day-3 to day-12 of culture, culture medium was collected and preserved for determination of inhibin B, anti-Müllerian hormone (AMH) and estradiol levels. At the end of the culture, after maturation, the status of the oocyte was evaluated. Follicular growth and their individual hormone production did not always correlate. Inhibin B was never secreted from follicles of less than 200 μm diameter, whether the follicles were examined when fresh or after freezing-thawing. Estradiol secretion was never observed in frozen-thawed follicles. AMH was mainly secreted between day-3 and day-9. Despite similar morphological aspects at the start of culture, follicles selected for in vitro folliculogenesis were found to be heterogeneous and differed in their ability to grow and to produce hormones, even if they had similar growth curves. Follicles from frozen-thawed ovaries developed slowly and produced fewer hormones than freshly collected follicles.

Involvement of anticentromere antibody in interference with oocyte meiosis and embryo cleavage

The aim of this study was to investigate the clinical significance of anticentromere antibody (ACA) among types of antinuclear antibody (ANA) in the properties of oocytes retrieved from infertile women. The rate of metaphase II oocytes or embryo cleavage was significantly decreased in patients with positive ACA compared with patients with negative ACA, suggesting that ACA is an essential marker for flawed oocytes in infertile women with any type of ANA.

Polarized Light Microscopy in Mammalian Oocytes

The meiotic spindle structure plays a key role in normal chromosome alignment and segregation during meiosis. Polarized light microscopy (PLM) allows non-invasive evaluation of the meiotic spindle of metaphase oocytes from different animal species. The purpose of this article is to review the use of PLM in animal reproduction, mainly in the assessment of the meiotic spindle in oocytes. A brief overview of the methods to assess the meiotic spindle is presented as well as the principles behind the PLM. The use of PLM to evaluate oocyte quality and spindle morphology is discussed and the results on the viability of the oocytes after being exposed to PLM are presented. Several researchers showed that PLM could be successfully implemented on cryopreservation, nuclear transfer and intracytoplasmic sperm injection procedures as a tool to improve the outcome of these procedures. In addition, PLM can be used to develop studies on oocyte maturation and spindle dynamics. However, the information on the practical use of this technology in farm animals is very limited and further studies are needed to assess the importance of PLM in animal reproduction.

Les secrets des dosages dans le liquide folliculaire

Only 5% of oocytes lead to life birth after IVF. Currently, it is difficult to evaluate oocyte quality on the sole basis of morphology criteria. Embryo morphology is considered as a good marker of potential implantation of embryo after ET, however it is not enough. Therefore, we need to develop non invasive assessment of oocyte quality. Research performed on follicular fluid may represent a new tool of increasing interest. The presence of G-CSF in follicular fluid could predict ongoing pregnancy. Cytokines, IL-7 and IL-17 could be also a predictor of success.

Mitochondrial functions on oocytes and preimplantation embryos

Oocyte quality has long been considered as a main limiting factor for in vitro fertilization (IVF). In the past decade, extensive observations demonstrated that the mitochondrion plays a vital role in the oocyte cytoplasm, for it can provide adenosine triphosphate (ATP) for fertilization and preimplantation embryo development and also act as stores of intracellular calcium and proapoptotic factors. During the oocyte maturation, mitochondria are characterized by distinct changes of their distribution pattern from being homogeneous to heterogeneous, which is correlated with the cumulus apoptosis. Oocyte quality decreases with the increasing maternal age. Recent studies have shown that low quality oocytes have some age-related dysfunctions, which include the decrease in mitochondrial membrane potential, increase of mitochondrial DNA (mtDNA) damages, chromosomal aneuploidies, the incidence of apoptosis, and changes in mitochondrial gene expression. All these dysfunctions may cause a high level of developmental retardation and arrest of preimplantation embryos. It has been suggested that these mitochondrial changes may arise from excessive reactive oxygen species (ROS) that is closely associated with the oxidative energy production or calcium overload, which may trigger permeability transition pore opening and subsequent apoptosis. Therefore, mitochondria can be seen as signs for oocyte quality evaluation, and it is possible that the oocyte quality can be improved by enhancing the physical function of mitochondria. Here we reviewed recent advances in mitochondrial functions on oocytes.

Effects of in vitro maturation and age on oocyte quality in the rhesus macaque Macaca mulatta

To evaluate oocyte quality in a primate model. Analysis of oocyte karyotype by chromosome spreading and oocyte spindles by confocal microscopy. Research laboratory, Caribbean Primate Research Center. Rhesus macaques aged 6-22 years. Fourteen females underwent both Regimen A (FSH + hCG) and Regimen B (FSH only) stimulation cycles to facilitate collection of mature and immature oocytes. Immature oocytes from Regimens A and B underwent in vitro maturation (IVM) to produce metaphase II oocytes. All metaphase II oocytes underwent gradual fixation to spread chromosomes or were fixed and stained with probes specific to alpha-tubulin, actin, and DNA for visualization of the meiotic spindle using confocal microscopy. Karyotype and meiotic spindle architecture differences among in vivo matured (IVO) and IVM oocytes from young and old rhesus macaques. In all, 4.7% of IVO oocytes (Regimen A) from young females were hyperhaploid versus 25.0% of IVM oocytes (Regimen B) from old females; 4.5% of IVO oocytes (Regimen A) from young females versus 51.5% of IVM oocytes (Regimen B) from old females displayed abnormal chromosome alignment on the metaphase spindle. IVM can induce meiotic anomalies in macaque oocytes, especially those obtained from older females. Results from this study provide possible explanations for the reported reduction in developmental competence of IVM primate oocytes.

Effect of temporary nuclear arrest by Phosphodiesterase 3‐Inhibitor on morphological and functional aspects of in vitro matured mouse oocytes

The present study aimed to analyze detailed morphological and functional characteristics of mouse in vitro matured oocytes after a pre-maturation culture (PMC) by temporary nuclear arrest with the specific phosphodiesterase 3-inhibitor (PDE3-I) Cilostamide. In a first experiment the lowest effective dose of Cilostamide was determined. Cumulus-oocyte complexes (COCs), isolated from small antral follicles, were exposed to different concentrations of Cilostamide (ranging from 0 (control) to 10 microM) for 24 hr. Afterwards, oocytes were removed from PDE3-I-containing medium and underwent in vitro maturation (IVM) for 16-18 hr. A concentration of 1 microM Cilostamide was the lowest effective dose for maximum level of inhibition and reversibility of meiosis inhibition. This concentration was used in further experiments to evaluate oocyte quality following IVM in relation to different parameters: kinetics of meiotic progression, metaphase II (MII) spindle morphology, aneuploidy rate, fertilization, and embryonic developmental rates. The results were compared to nonarrested (in vitro control) and in vivo matured oocytes (in vivo control). Following withdrawal of the inhibitor, the progression of meiosis was more synchronous and accelerated in arrested when compared to nonarrested oocytes. A PMC resulted in a significant increase in the number of oocytes constituting a MII spindle of normal morphology. None of the oocytes exposed to PDE3-I showed numerical chromosome alterations. In addition, fertilization and embryonic developmental rates were higher in the PMC group compared to in vitro controls, but lower than in vivo controls. These results provide evidence that induced nuclear arrest by PDE3-I is a safe and reliable method to improve oocyte quality after IVM.