| Objective To investigate the effect of low oxygen on in-vitro fertilization, embryonicdevelopment and clinical outcome.Methods A prospective randomized study including265patients received infertiletreatment by using a long ovulation induction protocol in our reproductive center fromMarch to May,2011. The patients were randomly allocated into two groups, the testgroup （156patients） and the control group （109patients）. In test group, the entireduration from insemination to day2or day3embryo transfer, which containedfertilization and cleavage embryo culture process were in three-gas incubatorscontaining5%O2, while oocytes and cleavage embryos were in common incubatorswith20%O2in control group.Result By comparing the two groups, the fertilization rate （84.4%VS80.8%**）,normal fertilization rate （72.0%VS68.7%*）, cleavage rate （97.6%VS96.1%**）,high-quality embryo rate （43.3%VS35.1%**） and available embryo rate （72.5%VS59.5%**） in test group were significantly higher than those in control group（**P<0.01,*P<0.05）, but the normal cleavage rate （97.7%VS98.0%）, biochemistrial pregnancyrate （50%VS39.4%%）, clinical pregnancy rate （44.9%VS35.8%） and ectopicpregnancy rate （8.6%VS12.8%） were not statistically different. There were nosignificant difference in patients’ age, duration of infertility, body mass index, basal sexual hormone, the number of matured oocytes, the day of embryo transfer and thenumber of embryos for transfer between two groups.Conclusion Low oxygen （5%O2） may improve embryonic development in somedegree by increasing the number of high-quality embryos and available embryos. Objective To study the effect of low oxygen on human in-vivo failed-matured oocytesin vitro maturation, fertilization and embryonic development in controlled ovarianhyperstimulation cycles.Methods A total of444failed-matured oocytes （GV and MI stage） derived from163patients who underwent ICSI cycles were randomly divided into two groups: the testgroup which had237in-vivo failed matured oocytes containing131GV stage oocytesand106MI stage oocytes; the control group which had207in-vivo failed matured oocytescontaining124GV stage oocytes and83MI stage oocytes. ICSI time was definited bythe morphology of first polar body extruding from oocytes and the size of perivitellinespace.The second polar body and pronuclei were observed16-18hours later after ICSIand two pronuclei were cultured until expanded blastosyst stage. The number ofmatured oocyte, zygote, two pronucleus （2PN）,2PN cleavage embryo, day24-cellembryo, day38-cell embryo, day3over6-cell embryo, day3high-quality embryo,blastocyst and high-quality blastocyst were recorded during culture respectively in different groups.Result （1） A total of183matured oocytes from255GV stage oocytes followed byIVM in two groups. The maturation rate, fertilization rate,2PN rate,2PN cleavagerate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cell embryo rate,day3high-quality embryo rate, blastocyst formation rate and high-quality blastocystformation rate were71.8%（183/255）,89.6%（164/183）,79.2%（145/183）,94.5%（137/145）,39.4%（54/137）,26.3%（36/137）,47.4%（65/137）,29.2%)40/137),21.9%（30/137） and16.7%（5/30） respectively. The day38-cell embryo rate in testgroup was significantly higher than that in control group（P<0.05）. The day3high-qua-lity embryo rate and blastocyst formation rate were also significantly higher than thosein control group （P<0.01）. There were no significantly difference on maturation rate,fertilization rate,2PN rate,2PN cleavage rate, day24-cell embryo rate, day3over6-cell embryo and high-quality blastocyst formation rate between two groups （P>0.05）.（2） A total of175matured oocytes from189MI stage oocytes followed by IVM intwo groups. The maturation rate, fertilization rate,2PN rate,2PN cleavage rate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cell embryo, day3high-quality embryo rate, blastocyst formation rate and high-quality blastocyst formationrate were92.6%（175/189）,90.3%（158/175）,79.4%（139/175）,91.5%（130/142）,50.0%（65/130）,29.2%（38/130）,54.6%（71/130）,25.4%（33/130）,17.7%（23/130） and34.8%（8/23） respectively. The fertilization rate and2PN rate in test group weresignificantly higher than those in control group （P<0.05） and there were nosignificantly difference on maturation rate,2PN cleavage rate, day24-cell embryorate, day38-cell embryo rate, day3over6-cell embryo, day3high-quality embryorate, blastocyst formation rate and high-quality blastocyst formation rate between twogroups （P>0.05）.（3） Both two stages （GV+MI）, the day3high-quality embryo rateand blastocyst formation rate in test group were significantly higher than those incontrol group （P<0.05）. The day3high-quality embryo rate in test group was significantly higher than that in control group （P<0.01） and there were no significantlydifference on maturation rate, fertilization rate,2PN rate,2PN cleavage rate, day24-cell embryo rate, day3over6-cell embryo and high-quality blastocyst formation ratebetween two groups （P>0.05）.Conclusion Low oxygen（5%O2） appears to optimize IVM by improving fertilizationand early embryonic development. Objective To study the effect of ascorbic acid （AA） on human in-vivo failed-maturedoocytes in vitro maturation, fertilization and embryonic development in controlledovarian hyperstimulation cycles.Methods According to the concentration of AA supplemented into the IVM mediaand the density of oxygen in incubator, a total of955failed-matured oocytes （GV andMI stage） derived from326patients who underwent IVF or ICSI cycles were randomlydivided into four groups: A5, B5, C5and D5.The oocytes were cultured in incubatorwith5%O2. For another four groups: A20, B20, C20and D20, the oocytes were culturedin incubator with20%O2. There was no AA supplemented into media in A5and A20groups,2.5mg/l AA was supplemented into media in B5and B20groups,5.0mg/l AAwas supplemented into media in C5and C20groups,10.0mg/l AA was supplementedinto media in D5and D20groups. Irrespective of the desity of oxygen, the955in-vivofailed matured oocytes were divided into A1, B1, C1and D1four groups, whose559 oocytes were in GV stage and A2, B2, C2, and D2four groups, whose396oocytes werein MI stage. There was no AA supplemented into media in A1and A2groups,2.5mg/lAA was supplemented into media in B1and B2groups,5.0mg/l AA was supplementedinto media in C1and C2groups,10.0mg/l AA was supplemented into media in D1andD2groups. Group without AA was considered as control group and others were testgroups compared to control group respectively. ICSI time was definited by themorphology of first polar body extruding from oocytes and the size of perivitellinespace.The second polar body and pronuclei were observed16-18hours later after ICSIand two pronuclei were cultured until expanded blastosyst stage.The number ofmatured oocyte, zygote, two pronucleus （2PN）,2PN cleavage embryo, day24-cellembryo, day38-cell embryo, day3over6-cell embryo, day3high-quality embryo,blastocyst and high-quality blastocyst were recorded during culture respectively indifferent groups.Result （1） There was no significantly difference on maturation rate, fertilization rate,2PN rate,2PN cleavage rate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cell embryo rate, day3high-quality embryo rate, blastocyst formation rate andhigh-quality blastocyst formation rate between A5and B5groups, A5and C5groups, A5and D5groups （P>0.05）.（2） There was no significantly difference on maturation rate,fertilization rate,2PN rate,2PN cleavage rate,day24-cell embryo rate, day38-cellembryo rate, day3over6-cell embryo rate, day3high-quality embryo rate, blastocystformation rate and high-quality blastocyst formation rate between A20and B20groups,A20and C20groups, A20and D20groups（P>0.05）.（3） The blastocyst formation rate inB1group was significantly higher than that in A1group （P<0.01） and there was nosignificantly difference on maturation rate, fertilization rate,2PN rate,2PN cleavagerate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cell embryo rate,day3high-quality embryo rate, blastocyst formation between two groups （P>0.05）.There was no significantly difference on maturation rate, fertilization rate,2PN rate, 2PN cleavage rate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cellembryo rate, day3high-quality embryo rate, blastocyst formation rate and high-qualityblastocyst formation rate between A1and C1groups, A1and D1groups （P>0.05）.（4）There was no significantly difference on maturation rate, fertilization rate,2PN rate,2PN cleavage rate, day24-cell embryo rate, day38-cell embryo rate, day3over6-cellembryo rate, day3high-quality embryo rate, blastocyst formation rate and high-qualityblastocyst formation rate between A2and B2groups, A2and C2groups, A2and D2groups （P>0.05）.Conclusions （1） Supplementation of ascorbic acid into IVM media didn’t improvein-vitro maturation, fertilization and embryonic development notably of human in-vivofailed-matured oocytes derived from controlled ovarian hyperstimulation cycles.（2）higher stable ascorbic acid with suitable concentration should be explored tosupplement into media to optimize IVM by anti-oxidative stress. |
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