| To increase the pregnancy rate in in vitro fertilization-embryo transfer(IVF-ET),more than one top quality oocyte and embryo are required. Forthis purpose, controlled ovarian hyperstimulation (COH) is routinely used.In COH, about 15% oocytes retrieved were immature and dischargedbecause they could not be fertilized in the past years. If the immatureoocytes could be mature in vitro, it will helpful to increase the number ofembryos in each cycle for ET and cryopreservation, improve thecumulative pregnancy rate and ultimately the results of assistedreproductive technology (ART). Objective: To study the effect of cumulus cells and culture period on in vitromaturation, in vitro fertilization and developmental competence ofimmature human oocytes derived from COH cycles. Establish an effectiveIVM protocol and investigate the clinical use of in vitro maturation (IVM)on ART. Methods: 1,Patients who had immature oocytes derived from COH cycles wereenrolled in the study. 2,All retrieved oocytes were classified as mature oocytes group(metaphase II, MII) and immature oocytes group. Immature oocytes wereclassified as oocyte-conora-cumulus complexes group (OCCC, withcumulus cells) and cumulus-free oocytes group (denuded oocytes, DO).Immature oocytes include metaphase I (MI) and germinal vesicle (GV)oocytes. Immature oocytes were cultured for 24h or 48h in vitro. 3,Oocytes were fertilized by intracytoplasmic sperm injection (ICSI)after matured in vitro. Oocytes matured in vivo were fertilized by IVF, ICSIor IVF+ICSI according to the programmed protocol. 4,Embryos derived from oocytes matured in vivo were chosen forembryo-transfer (ET) firstly and IVM group secondly. The supernumeraryembryos were cryopreserved after ET. 5,The effect of cumulus cells and culture period on IVM, fertilizationand developmental competence of immature human oocytes werecompared. Normal fertilization rate, abnormal fertilization rate, cleavagerate and top quality embryo formation rate of oocytes matured in vivo andin vitro group were compared. The outcomes of ART were compared toprove the positively effect of IVM on ART. Results: 1,70.5% of immature oocytes could mature after IVM for 24h,another 11.2% matured after 48h. The maturation rate was 81.7%。 2,There is no difference in maturation rate, fertilization rate, cleavagerate and top quality embryo formation rate between OCCC group and DOgroup(P>0.05). There is no difference in total maturation rate, fertilizationrate, cleavage rate and top quality embryo formation rate between GV andMI oocytes(P>0.05), whereas the maturation rate of 24h of GV oocytes inDO group was higher than in OCCC group(P<0.05). Oocytes matured invitro for 24h have the similar fertilization rate, cleavage rate whencompared with oocytes matured in vitro for 48h(P>0.05). Although topquality embryo formation rate was better in 24h group(28.3% versus12.5%), the difference has not significant(P>0.05). 3,There is no difference in fertilization rate and cleavage rate betweenoocytes maturated in vivo and in vitro(P>0.05), but top quality embryoformation rate derived from IVM oocytes was significantly lower thanoocytes matured in vivo (P<0.05). 4,IVM of immature oocytes increased the number of embryos for ETand cryopreservation in some patients, reduced the cycle cancellation rate.When compared the results of 14 patients in 2004 and 17 patients in 2003who has less than 2 embryos derived from oocytes matured in vivo fortransfer, we concluded that IVM improved the results of ART. Conclusions: 1. Most of the immature human oocytes derived from COH cyclescould mature in vitro and have the potential of fertilization and earlycleavage. 2. Although after 24h culture, the maturation rate of GV oocytes inDO group was higher than them in OCCC group, it could be concluded thatthe cumulus cells had no positive effect on maturation, fertilization anddevelopment competence of immature oocytes when they were cultured ina suitable system. 3. Most immature oocytes could mature after cultured for 24h in vitro.Prolonged... |
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