Analysis of developmental ability of human embryos from blastomere configuration after zona-free ICSI

Abstract

Human oocytes are surrounded by an elastic glycoprotein matrix called the zona pellucida. In case of IVF, zona-free human oocytes are infrequently encountered because of cracking the zona pellucida. We had encountered delivery cases after blastocyst transfer that was performed by zona-free ICSI. Although one of the major roles of zona pellucida is prevention of blastomere separation, zona-free embryo culture can be seen various blastomere configuration in precompaction stage. On the basis of blastomere configuration, we numbered the total blastomere contact points and observed development to the blastocyst stage. This study was undergoing IVF treatment between September 2008 and April 2011. Of all 50 matured zona-free oocytes were performed by ICSI. Then fertilized embryo was cultured in P1 media and observed at day 1 evening, day 2 morning and evening. All embryos were observed blastomere configuration and counted total blastomere contact points. After observation on day 2 evening, the embryos were cultured to the blastocyst stage until day 7. Development rate of blastocyst stage after zona-free ICSI was 46.0% (23/50). Average number of total blastomeres contact points of embryos developed to blastocyst were 0.39, 5.22 and 6.52, at day 1 evening, day 2 morning and evening respectively. Moreover, embryos that did not developed to blastocyst stage showed 0.33, 3.52 and 4.70 contact points respectively. Embryos that developed to blastocyst showed a larger number of blastomere contact points than the group of embryos that did not developed to the blastocyst group when monitored at day 2 of culture in the morning and evening. (P<0.05)