Research On In Vitro Maturation Of Human Immature Oocytes

Objective:The study established the culture system of human immature oocytes in in vitro maturation(IVM) associated with in vitro fertilization(IVF),and investigated the influencing factors of IVM.Methods:the immature oocytes from 52 patients with patients' consents who accepted IVF or intra-cytoplasmic sperm injection(ICSI) in the reproductive medicine research centre of No.1 Hospital of Lanzhou University were investigated. The immature oocytes were cultured until maturation then fertilized by ICSI,and the embryos were cultured.The high-quality embryos were cryopreserved under the programmed slow freezing protocol.The maturation rate and the fertilization rate in different culturing time in oocyte maturation medium were analyzed.In this research, we divided the immature oocytes into germinal vesicle(GV) stage group and metaphaseâ… (MI) stage group to investigate the difference in maturation rate and fertilization rate.We also put the immature oocytes into nudeooeyte(NO) group and cumulus-oocytes complexes(COCs) group to analyze the influence of cumulus-oocytes in IVM.And the differences between in vitro maturation group and in vivo maturation group at the same period were studied.Results:In this study,total 136 immature oocytes were cultured.96 of them developed to Mâ…¡stage,the maturation rate is 70.6%;55 oocytes got fertilization,the fertilization rate is 55.2%;35 embryo got cleavage,the cleavage rate is 64.2%.In addition,13 high-quality embryos which had further viability were cryopreserved. The maturation rate and the fertilization rate of immature oocytes which were cultured immediately in oocye matration medium are significantly higher than those cultured later.The immature oocytes at metaphaseâ… (MI) can get mature easier than which at germinal vesicle(GV).The maturation rate and the fertilization rate of COCs group are higher than that of NO group.Compared to in vivo maturation group,the in vitro maturation group presented higher cleavage rate significantly.Conclusions:The culture system for IVM combined with in vitro fertilization was established in this study.This culture system afforded immature human oocytes the ability to mature in vitro,and developed into earlier embryos.For immature oocytes,oocytes maturation medium were better than human tubal fluid.Our result showed that culture oocytes together with cumulus-oocytes can raise the maturation rate and improve the quality of oocytes.The development viability of embryos in IVM was lower than that in IVF/ICSI.And the immature oocytes can develop into earlier embryos for embryo transfer.