<正>In conventional in vitro fertilization（IVF）.since sperm metabolites,granular cells and death spermatozoa may consume lots of energy in the culture medium due to longer co-incubation of oocytes and high concentration spermatozoa.The oocytes are in innutritive environment,which leads to the hardening of oocyte plasma membrane. At the same time,the high levels of estradiol（E2） and progestone（P） produced by granular cells have direct toxic effects to affect embryo cleavage,development and implantation.Therefore,short-term insemination is adopted in more and more reproductive centers. 1.Short-term insemination may increase oocyte-utilization rate,high-quality embryo rate and embryo-utilization rate.2.Retention of cumulus cells may reduce polyspermic fertilization rate.Studies have indicated that the polyspermic fertilization rate is significantly higher in cumulus cell-free group than in cumulus cell group.In short-term insemination,the remaining oocytes should retain cumulus cells to reduce polyspermic fertilization under the circumstance of successful fertilization.3.There is no significant difference in 2PN embryo chromosome abnormality between conventional IVF group and short-term insemination group.4.Short-term insemination may significantly decrease ICSI rate and partial ICSI rate.5.Complete fertilization failure rate significantly decreases in short-term insemination. Short-term insemination reduces unfavourable factors for embryo development,therefore increases high quality embryo rate.If short-term insemination is adopted in IVF,under the circumstance of successful fertilization,the remaining oocytes should retain cumulus cells as much as possible to reduce polyspermic fertilization,improve oocyteutilization rate and optimize IVF outcomes.
