Importance of In Vitro Embryo Model Procedure Standardization.

In vivo studies offer a detailed understanding of organism functioning, surpassing the insights provided by in vitro studies. These experiments are crucial for comprehending disease emergence, progression, and associated mechanisms in humans, as well as for developing treatments. When choosing experimental models, factors such as genomic similarity, physiological relevance, ethical appropriateness, and economic feasibility must be considered. Standardized protocols enhance the reliability, and reproducibility of scientific methods, promoting the assessment of research in the scientific literature. Researchers conducting embryo studies should establish and document standardized protocols for increased data comparability. Standardization is vital for scientific validity, reproducibility, and comparability in both in vivo and in vitro studies, ensuring the accuracy and reliability of experimental results and advancing scientific knowledge.

The density of the inner cell mass is a new indicator of the quality of a human blastocyst: a valid supplement to the Gardner scoring system.

STUDY QUESTION: Can the density of the inner cell mass (ICM) be a new indicator of the quality of the human blastocyst? SUMMARY ANSWER: The densification index (DI) developed in this study can quantify ICM density and provide positive guidance for ploidy, pregnancy, and live birth. WHAT IS KNOWN ALREADY: In evaluating the quality of ICM, reproductive care clinics still use size indicators without further evaluation. The main disadvantage of this current method is that the evaluation of blastocyst ICM is relatively rough and cannot meet the needs of clinical embryologists, especially when multiple blastocysts have the same ICM score, which makes them difficult to evaluate further. STUDY DESIGN, SIZE, DURATION: This observational study included data from 2272 blastocysts in 1991 frozen-thawed embryo transfer (FET) cycles between January 2018 to November 2021 and 1105 blastocysts in 430 preimplantation genetic testing cycles between January 2019 and February 2023. PARTICIPANTS/MATERIALS, SETTING, METHODS: FET, ICSI, blastocyst culture, trophectoderm biopsy, time-lapse (TL) monitoring, and next-generation sequencing were performed. After preliminary sample size selection, the 11 focal plane images captured by the TL system were normalized and the spatial frequency was used to construct the DI of the ICM. MAIN RESULTS AND THE ROLE OF CHANCE: This study successfully constructed a quantitative indicator DI that can reflect the degree of ICM density in terms of fusion and texture features. The higher the DI value, the better the density of the blastocyst ICM, and the higher the chances that the blastocyst was euploid (P < 0.001) and that pregnancy (P < 0.001) and live birth (P = 0.005) were reached. In blastocysts with ICM graded B and blastocysts graded 4BB, DI was also positively associated with ploidy, pregnancy, and live birth (P < 0.05). ROC analysis showed that combining the Gardner scoring system with DI can more effectively predict pregnancy and live births, when compared to using the Gardner scoring system alone. LIMITATIONS, REASONS FOR CAUTION: Accurate calculation of the DI value places high demands on image quality, requiring manual selection of the clearest focal plane and exposure control. Images with the ICM not completely within the field of view cannot be used. The association between the density of ICM and chromosomal mosaicism was not evaluated. The associations between the density of ICM and different assisted reproductive technologies and different culture conditions in embryo laboratories were also not evaluated. Prospective studies are needed to further investigate the impact of ICM density on clinical outcomes. WIDER IMPLICATIONS OF THE FINDINGS: ICM density assessment is a new direction in blastocyst assessment. This study explores new ways of assessing blastocyst ICM density and develops quantitative indicators and a corresponding qualitative evaluation scheme for ICM density. The DI of the blastocyst ICM developed in this study is easy to calculate and requires only TL equipment and image processing, providing positive guidance for clinical outcomes. The qualitative evaluation scheme of ICM density can assist embryologists without TL equipment to manually evaluate ICM density. ICM density is a simple indicator that can be used in practice and is a good complement to the blastocyst scoring systems currently used in most centers. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Key Research & Development Program of China (2021YFC2700603). The authors report no financial or commercial conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Multiple gestation associated with infertility therapy: a committee opinion.

This Committee Opinion provides practitioners with suggestions to reduce the likelihood of iatrogenic multiple gestation resulting from infertility treatment. This document replaces the document of the same name previously published in 2012 (Fertil Steril 2012;97:825-34 by the American Society for Reproductive Medicine).

A Simple and Efficient Solution to Eliminate Evaporation in Mammalian Embryo Cultures.

The aim of this brief report is to offer a solution for a problem that compromises the quality of in vitro-produced mammalian embryos. The harmful effects of evaporation-induced osmotic changes in mammalian embryo cultures have been recognized only recently. In this technical report, we describe a modified embryo culture dish (Humdish) that provides consistent >97% humidity and fully eliminates osmotic changes in the commonly used drop-under-oil culture systems from day 0 to 6. As an additional benefit, the Humdish also increases the temperature stability of cultures. If subsequent laboratory and clinical experiments prove its value, our suggested approach may help to improve the in vitro environment and quality of all preimplantation stage mammalian embryos, including the most sensitive ones produced from artificial gametes or by somatic cell nuclear transfer.

Back to the future: optimised microwell culture of individual human preimplantation stage embryos.

Although in vitro culture of human embryos is a crucial step in assisted reproduction, the lack of focused research hampers worldwide standardisation and consistent outcomes. Only 1.2% of research papers published in five leading journals in human reproduction in 2019 focused on in vitro culture conditions, creating the impression that the optimisation process has approached its limits. On the other hand, in vitro culture of mammalian embryos is based on old principles, while there is no consensus on basic issues as density, time, medium change, gas atmosphere and small technical details including the way of drop preparation. This opinion paper aims to highlight and analyse the slow advancement in this field and stimulate research for simple and affordable solutions to meet the current requirements. A possible way for advancement is discussed in detail. Selection of embryos with the highest developmental competence requires individual culture and modification of the widely used "drop under oil" approach. Current use of three-dimensional surfaces instead of large flat bottoms is restricted to time-lapse systems, but these wells are designed for optical clarity, not for the needs of embryos. The size and shape of the original microwells (Well of the Well; WOW) offer a practical and straightforward solution to combine the benefits of communal and individual incubation and improve the overall quality of cultured embryos.

A New Day 4 Grading System to Assess Embryo Quality in Frozen Embryo Transfer Cycles.

To present a new day 4 (D4) embryo grading system to assess embryos in frozen-thawed embryo transfer (FET) cycles. A new grading system (grades A-E) was developed from the 2011 ESHRE Istanbul Consensus for D4 embryos in FET cycles. Embryos with complete compaction were classified as grade A; those with partial compaction were assigned as grade B; and those without compaction were classified as grades C, D, and E according to their different blastomere number ratio (BNR; number of embryo blastomeres on D4/number of embryo blastomeres on D3, D4/D3). Embryos with a BNR of ≥ 1.5 were defined as grade C, those with a BNR of ≥ 1.2 and < 1.5 were defined as grade D, and those with a BNR of ≥ 1.0 and < 1.2 were defined as grade E. Using this proposed grading model, 5460 embryos with known implantation data were retrospectively analyzed after D4 transfer in FET cycles. The transferred embryos exhibited a similar declining trend in implantation and live birth rates from the top grade A to the lowest grade E. The in vitro fertilization group showed increased implantation rates of grade B and E embryos compared with the intracytoplasmic sperm injection group (grade B: 41.99%, 34.63%, χ2 = 5.84, p < 0.05 and grade E: 18.98%, 14.08, χ2 = 75.62, p < 0.01). Receiver-operating characteristic analysis revealed that our proposed model predicted the implantation outcomes and live birth rates of all embryos (area under the curve = 0.65; 95% confidence interval [CI],0.63-0.66; p < 0.01 and AUC = 0.73; 95%CI, 0.65-0.84; p < 0.001, respectively). This study demonstrates that the new grading system provided by us can be a useful tool for assisting embryo selection via changes in embryo morphology. D4 embryo transfer provides a simple and applicable method for FET cycles in daily practice.

Introduction: Key performance indicators in assisted reproductive technologies.

Assisted reproductive technology (ART) has been so widely deployed across the world that over 1% of all births are now ART babies, with even higher percentages in the Nordic countries. As pregnancy rates are limited by technical, population, and inherent limitations of human reproduction, key performance indicators should be defined for all the different facets of ART to measure the efficacy of the procedure.

The complex microbiome from native semen to embryo culture environment in human in vitro fertilization procedure.

BACKGROUND: Only a few microbial studies have conducted in IVF (in vitro fertilization), showing the high-variety bacterial contamination of IVF culture media to cause damage to or even loss of cultured oocytes and embryos. We aimed to determine the prevalence and counts of bacteria in IVF samples, and to associate them with clinical outcome. METHODS: The studied samples from 50 infertile couples included: raw (n = 48), processed (n = 49) and incubated (n = 50) sperm samples, and IVF culture media (n = 50). The full microbiome was analyzed by 454 pyrosequencing and quantitative analysis by real-time quantitative PCR. Descriptive statistics, t-, Mann-Whitney tests and Spearman's correlation were used for comparison of studied groups. RESULTS: The study involved normozoospermic men. Normal vaginal microbiota was present in 72.0% of female partners, while intermediate microbiota and bacterial vaginosis were diagnosed in 12.0 and 16.0%, respectively. The decreasing bacterial loads were found in raw (35.5%), processed (12.0%) and sperm samples used for oocyte insemination (4.0%), and in 8.0% of IVF culture media. The most abundant genera of bacteria in native semen and IVF culture media were Lactobacillus, while in other samples Alphaproteobacteria prevailed. Staphylococcus sp. was found only in semen from patients with inflammation. Phylum Bacteroidetes was in negative correlation with sperm motility and Alphaproteobacteria with high-quality IVF embryos. CONCLUSION: Our study demonstrates that IVF does not occur in a sterile environment. The prevalent bacteria include classes Bacilli in raw semen and IVF culture media, Clostridia in processed and Bacteroidia in sperm samples used for insemination. The presence of Staphylococcus sp. and Alphaproteobacteria associated with clinical outcomes, like sperm and embryo quality.

'There is only one thing that is truly important in an IVF laboratory: everything' Cairo Consensus Guidelines on IVF Culture Conditions.

This proceedings report presents the outcomes from an international expert meeting to establish consensus guidelines on IVF culture conditions. Topics reviewed and discussed were: embryo culture - basic principles and interactions; temperature in the IVF laboratory; humidity in culture; carbon dioxide control and medium pH; oxygen tension for embryo culture; workstations - design and engineering; incubators - maintaining the culture environment; micromanipulation - maintaining a steady physcochemical environment; handling practices; assessment practices; culture media - buffering and pH, general composition and protein supplementation, sequential or single-step media for human embryo culture; use and management - cold chain and storage; test equipment - calibration and certification; and laboratory equipment and real-time monitoring. More than 50 consensus guideline points were established under these general headings.

Morphology, developmental stages and quality parameters of in vitro-produced equine embryos.

Intracytoplasmic sperm injection (ICSI) is used to produce equine embryos invitro. The speed of embryo development invitro is roughly equivalent to what has been described for embryos produced invivo. Morphological evaluations of ICSI-produced embryos are complicated by the presence of debris and the dark nature of equine embryo cytoplasm. Morulas and early blastocysts produced invitro appear similar to those produced invivo. However, with expansion of the blastocyst, distinct differences are observed compared with uterine embryos. In culture, embryos do not undergo full expansion and thinning of the zona pellucida (ZP) or capsule formation. Cells of the inner cell mass (ICM) are dispersed, in contrast with the differentiated trophoblast and ICM observed in embryos collected from uteri. As blastocysts expand invitro, embryo cells often escape the ZP as organised or disorganised extrusions of cells, probably through the hole incurred during ICSI. Quality assessment of invitro-produced early stage equine embryos is in its infancy, because limited information is available regarding the relationship between morphology and developmental competence. Early embryo development invivo is reviewed in this paper, with comparisons made to embryo development invitro and clinical assessments from a laboratory performing commercial ICSI for >15 years.

Fine-tuning blastocyst selection based on morphology: a multicentre analysis of 2461 single blastocyst transfers.

RESEARCH QUESTION: Which blastocyst morphology parameter is associated with live birth after controlling for female age and endometrial receptivity? DESIGN: Retrospective study including fresh single blastocyst transfers (n = 2461) where the value of serum progesterone on day of human chorionic gonadotrophin trigger (PdHCG) was available. Generalized estimating equation regression models evaluated the independent effects of developmental stage (DevSt), inner cell mass (ICM) and trophectoderm grade on live birth rates while controlling for the confounding effects of female age and PdHCG. RESULTS: DevSt was strongly associated with the probability of live birth (P < 0.0001) independently of female age (odds ratio [OR] 0.89, 95% confidence interval [CI] 0.87-0.91) and PdHCG (OR 0.80, 95% CI 0.74-0.87). For full blastocysts, expanded blastocysts and hatching blastocysts, addition of ICM and trophectoderm grading in the multivariable analysis suggested that besides female age (OR 0.92, 95% CI 0.90-0.94) and PdHCG (OR 0.80, 95% CI 0.73-0.87), only DevSt (P = 0.001) and trophectoderm quality (P = 0.004) were independent predictors of live birth, while the predictive capacity of ICM was no longer significant. The mean probability of live birth was highest for AA blastocysts (35.0%), followed by BA blastocysts (31.2%) and AB blastocysts (27.7%). CONCLUSION: This large study analyses for the first time the independent role of blastocyst morphology in predicting live birth while controlling for female age and PdHCG. Its findings suggest that DevSt and then trophectoderm grade are stronger predictors of live birth over ICM grade when selecting a single blastocyst for transfer.

Controversies in ART: can the IVF laboratory influence preimplantation embryo aneuploidy?

Published reports have indicated that rates of preimplantation embryo aneuploidy in a control donor population may vary between IVF centres. This suggests that location-specific conditions, in the clinic, IVF or genetics laboratory, may be influencing the chromosome dynamics or diagnosis. More recent reports suggest that rates of embryo mosaicism, representing mitotic errors, may vary between IVF centres. This would suggest perhaps a laboratory-controlled variable is influencing mitotic cell division during preimplantation embryo development. Various IVF laboratory-controlled factors may be impacting chromosome separation and segregation. Variables including type of culture media, pH, temperature, osmolality and oxygen concentration could all be possible factors influencing embryo aneuploidy. Furthermore, laboratory techniques, method of insemination, laser use or handling of biopsied cells may also influence genetic results. These IVF laboratory variables will be reviewed and literature suggesting a possible link to mitotic aneuploidy/mosaicism discussed.

Parameters of the Mouse Embryo Assay that affect detection of peroxides in mineral oil.

RESEARCH QUESTION: Can culture conditions influence the sensitivity of a Mouse Embryo Assay and its potential to detect peroxide-related toxicity in mineral oil samples? DESIGN: Protein type and concentration, embryo density and culture dish design were selected as the variables in the culture system with the potential to influence the assay's sensitivity. Fresh 1-cell mouse embryos were cultured under mineral oil samples with known peroxide concentrations. Protein type (human serum albumin [HSA] + α/ß-Globulins versus HSA versus bovine serum albumin [BSA]), concentration (5 mg/ml versus 0.5 mg/ml), embryo density (25 versus 3 µl/embryo) and culture dish (Petri versus micro-well dish) were adjusted to define the culture conditions with the highest sensitivity. RESULTS: High concentrations of peroxides can be easily detected by current quality control standards. However, for oil samples with a lower concentration of peroxides, supplementing the culture medium with 5 mg/ml of HSA + alpha/beta-globulins or with HSA resulted in an increased detection of embryo toxicity compared with when BSA was used as the protein supplement. The sensitivity of the assay was greatly reduced when embryos were cultured in groups and when certain micro-well dishes were used. CONCLUSIONS: Current quality control protocols may not be sensitive enough to identify low concentrations of peroxides, which, if undetected, can increase over time and become potentially harmful during gamete and embryo culture. The different parameters established in this study allow the sensitivity of the Mouse Embryo Assays to be optimized to specifically detect peroxides in mineral oil samples prior to their release into the market and their broad use in human IVF.

Unstable osmolality of microdrops cultured in non-humidified incubators.

PURPOSE: To investigate the stability of osmolality in non-humidified and humidified incubators for assisted reproductive technologies (ART). METHODS: Drops of three single-step culture media (media A, B, and C) were incubated for 5 or 6 days covered with four different mineral oils (oils A, B, C, and D) in non-humidified incubator A, non-humidified incubator B, or humidified incubator C to investigate the effects of incubator environment (humidification), drop volume, culture media, and mineral oil on the stability of osmolality in microdrops. RESULTS: A significant and linear increase was shown in the osmolality of 50-µL and 200-µL microdrops covered with mineral oil during 5 days incubation in non-humidified benchtop incubators. The maximum increase was 20 mOsm/kg, and the extent of the increase was affected by microdrop volume and possibly by the type of mineral oil used to cover the drops. In contrast, the osmolality of 50-µL and 200-µL microdrops did not change during 5 days incubation in a humidified benchtop incubator. CONCLUSIONS: Mineral oil alone may not adequately prevent gradual changes in the osmolality of low-volume microdrops during extended in vitro culture of human embryos in non-humidified incubators. As a result, the osmolality may increase to high enough levels to stress some human embryos and adversely affect clinical outcomes. We therefore recommend that the stability of osmolality should be given more consideration to ensure optimal culture conditions for ART.

Extracellular vesicles derived from endometrial human mesenchymal stem cells enhance embryo yield and quality in an aged murine model†.

Advanced age is a risk factor undermining women's fertility. Hence, the optimization of assisted reproduction techniques is an interdisciplinary challenge that requires the improvement of in vitro culture systems. Here, we hypothesize that supplementation of embryo culture medium with extracellular vesicles from endometrial-derived mesenchymal stem cells (EV-endMSCs) may have a positive impact on the embryo competence of aged oocytes. In this work, 24 weeks old B6D2 female mice were used as egg donors and in vitro fertilization assays were performed using males from the same strain (8-12 weeks); the presumptive zygotes were incubated in the presence of 0, 10, 20, 40, or 80 µg/ml of EV-endMSCs. The results from the proteomic analysis of EV-endMSCs and the classification by Reactome pathways allowed us to identify proteins closely related with the fertilization process. Moreover, in our aged murine model, the supplementation of the embryo culture medium with EV-endMSCs improved the developmental competence of the embryos as well as the total blastomere count. Finally, gene expression analysis of murine blastocysts showed significant changes on core genes related to cellular response to oxidative stress, metabolism, placentation, and trophectoderm/inner cell mass formation. In summary, we demonstrate that EV-endMSCs increase the quality of the embryos, and according to proteomic and genomic analysis, presumably by modulating the expression of antioxidant enzymes and promoting pluripotent activity. Therefore, EV-endMSCs could be a valuable tool in human assisted reproduction improving the developmental competence of aged oocytes and increasing the odds of implantation and subsequent delivery.

Blastocyst culture and transfer in clinically assisted reproduction: a committee opinion.

The purposes of this Practice Committee Opinion, which replaces the 2013 ASRM Practice Committee Opinion of the same name (Fertil Steril 2013; 99:667-72), are to review the literature regarding the clinical application of blastocyst transfer and identify the potential risks and laboratory issues related to the use of this technology. This document does not apply to patients undergoing blastocyst culture and transfer for preimplantation genetic testing.

Effect of the Air Filtration System Replacement on Embryo Quality in the Assisted Reproduction Laboratory.

Improving infrastructural conditions of the in vitro fertilization laboratory, such as the air quality, has profound positive effects on embryo culture. Poor environmental conditions reduce the rate of embryo formation and, therefore, of pregnancy. This review article presents important publications regarding the impact of air quality in human reproduction laboratories on embryo quality, pregnancy success, and live births. The studies demonstrate that the replacing the air filtration system improves significantly the environmental air quality, and, consequently, improves laboratory parameters, such as the fertilization rate, the number of blastocysts, the embryo implantation rate, and the number of live births. On the other hand, improving air quality decreases the number of abortions. Therefore, environmental parameters that improve embryo quality and increase healthy child birth rates must be the main targets for the assisted reproduction laboratory quality control.

Melhorar as condições de infraestrutura do laboratório de fertilização in vitro, com influência na qualidade do ar, tem efeitos positivos profundos na qualidade do embrião. As más condições ambientais do ar reduzem a taxa de sucesso na formação de embriões e a taxa de gravidez. Este artigo de revisão apresenta importantes publicações sobre o impacto da qualidade do ar dentro do laboratório de reprodução humana na qualidade do embrião, no sucesso de gravidez e no número de nascidos vivos. Os estudos demonstram que a troca do sistema de filtração de ar melhora significativamente a qualidade do ar ambiente, e consequentemente, melhora os parâmetros laboratoriais, tais como a taxa de fertilização, o número de blastocistos, a taxa de implantação e o número de nascidos vivos. Por outro lado, a melhora da qualidade do ar diminui o número de abortos. Portanto, os parâmetros ambientais que melhoram a qualidade do embrião e aumentam as taxas de nascimentos de crianças saudáveis devem ser os principais alvos para o controle de qualidade do laboratório de reprodução assistida.

Diagnostic efficacy of blastocoel fluid and spent media as sources of DNA for preimplantation genetic testing in standard clinical conditions.

OBJECTIVE: To determine whether blastocoel fluid (BF) or spent blastocyst medium (SBM) is a suitable template for genotype and/or karyotype assessment of in vitro fertilization-generated embryos. DESIGN: Prospective blinded study. SETTING: Genetic laboratory. PATIENT(S): From 26 patients undergoing preimplantation genetic testing (PGT) treatments, 103 trophectoderms (TE), 92 BF samples, and 72 SBM samples. INTERVENTION(S): The BF and SBM were retrieved at the time of TE biopsy. Two DNA extraction strategies were evaluated on independent BF and SBM samples. Further enrolled samples were processed using next-generation sequencing and quantitative polymerase chain reaction for assessment of monogenic disorders (PGT-M) or aneuploidy (PGT-A). MAIN OUTCOME MEASURE(S): DNA amplification and concordance rates across BF, SBM, and TE to assess diagnostic efficiency. RESULT(S): No differences were detected among the DNA extraction methods tested. In PGT-M tests, for BF and SBM, 2.9% and 20.8% of all samples, respectively, produced a diagnosis concordant with the corresponding TE (n = 2 of 69 and 15 of 72, respectively). The SBM samples were associated with higher discordance rates and higher artifacts/contamination detection compared with BF. In multiple occasions, the maternal mutated variant was detected in the SBM of homozygous wild-type embryos, showing evidence of maternal DNA persistence in culture medium. In PGT-A tests, BF analysis showed high amplification failure rates (65.2%) and an overall concordance rate of 37.5% among amplified samples. CONCLUSION(S): Based on current methodologies, BF and SBM genetic analyses do not provide sufficiently reliable results to be employed clinically. Until the risk of maternal contamination can be properly prevented, SBM should not be used for PGT-M purposes.

Effect of the air filtration system replacement on embryo quality in the assisted reproduction laboratory / Efeito da troca do sistema de filtragem do ar na qualidade embrionária no laboratório de reprodução assistida

Abstract Improving infrastructural conditions of the in vitro fertilization laboratory, such as the air quality, has profound positive effects on embryo culture. Poor environmental conditions reduce the rate of embryo formation and, therefore, of pregnancy. This review article presents important publications regarding the impact of air quality in human reproduction laboratories on embryo quality, pregnancy success, and live births. The studies demonstrate that the replacing the air filtration system improves significantly the environmental air quality, and, consequently, improves laboratory parameters, such as the fertilization rate, the number of blastocysts, the embryo implantation rate, and the number of live births. On the other hand, improving air quality decreases the number of abortions. Therefore, environmental parameters that improve embryo quality and increase healthy child birth ratesmust be themain targets for the assisted reproduction laboratory quality control.

Resumo Melhorar as condições de infraestrutura do laboratório de fertilização in vitro, com influência na qualidade do ar, tem efeitos positivos profundos na qualidade do embrião. As más condições ambientais do ar reduzem a taxa de sucesso na formação de embriões e a taxa de gravidez. Este artigo de revisão apresenta importantes publicações sobre o impacto da qualidade do ar dentro do laboratório de reprodução humana na qualidade do embrião, no sucesso de gravidez e no número de nascidos vivos. Os estudos demonstram que a troca do sistema de filtração de ar melhora significativamente a qualidade do ar ambiente, e consequentemente, melhora os parâmetros laboratoriais, tais como a taxa de fertilização, o número de blastocistos, a taxa de implantação e o número de nascidos vivos. Por outro lado,amelhora da qualidade do ar diminui o número de abortos. Portanto, os parâmetros ambientais que melhoram a qualidade do embrião e aumentam as taxas de nascimentos de crianças saudáveis devem ser os principais alvos para o controle de qualidade do laboratório de reprodução assistida.

[Method validation of a critical parameter in human embryos culture: culture media pH]. / Validation de la mesure d'un paramètre critique en culture d'embryons humains : le pH.

In vitro human embryos culture depends largely on the atmospheric conditions within the incubators of the laboratory. The pH of culture media, an indirect reflection of the CO2 content inside these incubators, is a critical parameter. Collaboration between the biochemistry and reproductive biology departments enabled the automated measurement of the pH in the culture medium on a blood gas analyzer. This method has been validated and evaluated. It is applicable in all laboratories whatever the medium and the conditions of culture. It allows strict monitoring of this parameter for the optimization of the culture conditions necessary to improve the results of in vitro fertilization attempts.