Since the development of ART, embryos have been cultured at 37 °C in an attempt to mimic the in vivo conditions and the average body temperature of an adult. However, a gradient of temperatures within the reproductive tract has been demonstrated in humans and several other mammalian species. Therefore, the aim of this study was to evaluate the effects of temperature variation treatments on mouse embryo quality through morphokinetic events, blastocyst morphology, the relative gene expression of Igf2, Bax, Bcl2 and Apaf1 and the metabolomics of individual culture media. Study groups consisted of 2 circadian treatments, T1 with embryos being cultured at 37 °C during the day and 35.5 °C during the night, T2 with 38.5 °C during the day and 37 °C during the night and a control group with constant 37 °C. Our main findings are that the lower-temperature group (T1) showed a consistent negative effect on mouse embryo development with “slow” cleaving embryos, poor-quality blastocysts, a higher expression of the apoptotic gene Apaf1, and a significantly different set of amino acids representing a more stressed metabolism. On the other hand, our higher-temperature group (T2) showed similar results to the control group, with no adverse effects on blastocyst viability.
compared between the two groups (Group A: day 5 blastocyst biopsy and Group B: day 6 blastocyst biopsy). RESULTS: Aneuploidy rate was significantly higher in group B compared to group A (37.6% vs 28.7%, respectively; P¼0.046). Day 5 blastocyst biopsies tends to be higher euploidy rate compared to day 6 blastocyst (43.9% vs 35.2%, respectively¼0.071). There were, however, no differences in the rate of segmental abnormality, complex abnormality or no-results rate between day 5 and day 6 blastocyst biopsies.
blastocyst and HQB prediction rate compared to traditional D3M was seen when CES was performed on images combining D1+D3 embryos with an average overall blastocyst prediction rate of 98% vs 86% (p¼0.02) and HQB prediction rate of 86% vs 66% (p¼0.01), respectively. When TLM was compared to CES, the above findings persisted, albeit statistical differences were attenuated. CONCLUSIONS: Simultaneous visual assessment of a patient's entire embryo cohort on D1+D3 significantly improves selection of embryos destined to become HQB compared to traditional methods which rely on the individual annotation of embryos and subsequent hierarchical ranking of these scores. This novel method is being proposed as a simple and reproducible way of predicting blastocyst formation with a higher blastocyst prediction rate compared with standard D3-morphology and time-lapse imaging. In combination with modern technology, these findings may be used in the development of cost-effective methods for enhanced embryo selection.OBJECTIVE: In human IVF, many studies have shown that embryos cultured in lower oxygen tension (5% O 2 ) have higher implantation rate, when compared with normaxic condition (20% O 2 ). However the beneficial effect of low oxygen tension in implantation remains unclear. This study aimed to investigate the expression of oxygen-dependent gene and implantation related protein in mouse embryo cultured under hypoxic and normaxic conditions. DESIGN: The 2-cell ICR mouse embryos were cultured to blastocyst stage under 3% O 2 tension (N¼186) and 20% O 2 tension (N¼189), respectively from four replicate experiments.MATERIALS AND METHODS: The blastocysts were collected from each experiment. The expressions of oxygen-related genes (HIF-1a and HIF-2a) were analyzed by real-time RT PCR. The protein levels of HIF-2a, COX-2, E-cadherin and LIFR were validated by Immunofluorescence analysis. Student's t test or one-way ANOVA test was used to evaluate statistical significance.RESULTS: The blastocyst formation and hatching rate (Mean AE SE) was significantly higher in 3% O 2 group when compared with 20% O 2 group (90.5AE3.3% vs. 77.8AE2.4% and 82.9AE6.9% vs. 70.7AE2.3%, respectively, P<0.5). The transcription levels of HIF-1a and HIF-2a were similar in two groups. Immunofluorescence staining showed the intensity of COX-2 and LIFR was higher in 3% O 2 than 20% O 2 group, respectively. Protein levels of HIF-2a was detected higher in the nucleus of 3% O 2 group. E-cadherin was significantly lower in 3% O 2 , compared with 20% O 2 group.CONCLUSIONS: This study has proposed that lower O 2 tension promotes blastocyst hatching and implantation by down-regulation of E-cadherin expression via HIF-2a/COX-2 pathway, it also provides more conducive environment by up-regulation of LIFR to facilitate implantation after blastocyst hatching. All these effects may be initiated and regulated by HIF-2a, which acts as key mediator in hypoxic environment.
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