Estimation of the Optimal Timing of Fertilization for Embryo Development ofIn Vitro-Matured Bovine Oocytes Based on the Times ofNuclear Maturation and Sperm Penetration

[摘要] References(33)Cited-By(3)The objective of this research was to estimate the optimal timing forfertilization to achieve proper embryonic development of in vitro-maturedbovine oocytes. First, cumulus-oocyte complexes were subjected to invitro maturation (IVM) for 14�?22 hr. The timing when 50% of oocytes reachedmetaphase II stage was estimated to be 17.5 hr after IVM start. Next, using oocytessubjected to IVM for 12�?30 hr, sperm penetration was examined after 4�?18 hr of invitro fertilization (IVF). A significant negative correlation between IVMduration and the timing when 50% of oocytes were penetrated by sperm after IVF start wasobserved (P<0.01). Finally, oocytes subjected to 12�?30 hr of IVM wereinseminated and cultured for 6 days to examine embryonic development. In the group with 22hr of IVM, the percentages of cleaved embryos and blastocysts were the highest values inall groups. According to the regression equation describing the time from nuclearmaturation to sperm penetration (x) and the percentage of blastocysts (y) (y=7.23x �?0.297x2, P<0.01), the blastocyst rate peaked when spermpenetration occurred at 12.2 hr after achieving nuclear maturation. In conclusion, underthe present IVM/IVF conditions, it was estimated that oocytes acquired their highestdevelopmental competence at about 30 hr after IVM start, and thus, the optimal IVMduration was calculated to be about 21 hr.

[学科分类] 兽医学

[关键词] bovine oocyte;IVF;IVM;nuclear maturation;sperm penetration