山羊卵母细胞的减数分裂进程

THE TEMPO OF MEIOSIS OF GOAT OOCYTES

本实验以随机屠宰山羊的卵巢为实验材料,研究了不同直径卵泡卵母细胞的减数分裂进程。结果显示,不同直径卵泡卵母细胞在体外成熟培养条件下的减数分裂能力不同:≤0.5mm直径卵泡的卵母细胞不能恢复减数分裂;0.8-1.2mm卵泡的卵母细胞可恢复减数分裂,但只能发育到MⅠ期,培养24h发育到MⅠ期比率60%;1.5-5.0mm卵泡卵母细胞已经完全获得减数分裂能力,培养24h发育到MⅡ的比例91%。完全获得减数分裂能力的1.5-5.0mm卵泡卵母细胞处于生发泡(GV)期的比率在成熟培养2-8h期间明显下降;其中,4-6h期间GⅤ比率下降最为迅速(由61%降低到19%,p<0.0005);体外培养6-12h期间MⅠ比率由25%上升到60%,随后下降,到24h仅有2%卵母细胞处于MⅠ期;培养16h有21%卵母细胞进入MⅡ期,24h 91%卵母细胞到达MⅡ期。对卵母细胞体外核成熟进程的数据做折线图计算结果表明,1.5-5.0mm卵泡卵母细胞减数分裂进程(各细胞周期事件出现和维持的时间)为:0-3.0h为GⅤ期,3.0-7.0h为前中期Ⅰ,7.0-14.6h为MⅠ期,14.6-18.4h处于后期-Ⅰ和末期-Ⅰ,18.4-24h为MⅡ期。本实验还证明,部分获得减数分裂能力(0.8-1.2mm卵泡)与完全获得减数分裂能力(1.5-5mm卵泡)的卵母细胞,其各细胞周期事件一旦发生,所需的时间是相同的。这些结果为进一步研究山羊卵母细胞减数分裂机制及其调控提供了重要的基础数据。

The meiotic progression of goat oocytes from follicles of different diameters was investigated in this study. The results were summarized as follows: (1) The in vitro meiotic maturation capacity was different among oocytes from follicles of different diameters. And thus oocytes from ≤ 0.5mm follicles were unable to resume meiosis; oocytes from 0.8-1.2mm follicles were capable to resume meiosis, but could develop only to M I stage (60% at 24 h); oocytes from 1.5-5mm follicles had acquired full-meiotic maturation capacity and 91% of them developed to M Ⅱ stage at 24 h of culture. (2) The percentage of oocytes with intact-germinal vesicles from 1.5-5mm follicles decreased significantly during 2-8 h of in vitro maturation and the decrease was even more rapid during 4-6 h of culture (from 60% to 19%, p<0.0005). The percentage of oocytes at M I-stage increased from 24% to 61% during 6-12 h of in vitro maturation, and it then decreased. By 24 h of culture, only 2% oocytes remained at M Ⅰ-stage. Twenty one percent of the oocytes in this group developed to MⅡ-stage at 16 h of culture, and by 24 h of culture, 91% were at MⅡ-stage. (3) Statistic analysis of the meiotic progression (the duration of each cell cycle stage) of oocytes from 1.5 -5mm follicles showed that GV stage lasted from 0 to 3 h of culture, prometaphase-Ⅰ stage was from 3.0 to 7.0 h, metaphase-Ⅰ stage was from 7.0 to 14.6 h, anaphase-Ⅰ / telophase-Ⅰ was from 14.6 to 18.4 h and metaphase-Ⅱ stage lasted from 18.4 to 24 h. (4) Whether the oocytes capable of GVBD and entrance of M I developed to M Ⅱ, the timing of meiotic progression prior to M I was similar. In summary, our results provided necessary data for studies on the mechanisms and control of meiosis in mammalian oocytes.