哺乳動物胚の初期発生における細胞内カルシウムイオンの役割

本研究旨在探讨细胞内钙离子对哺乳动物胚胎发育的影响。1）从受精开始到振荡结束，连续监测体外受精卵母细胞内Ca^<2+>浓度。数据显示，受精后3-4小时，细胞内Ca^2+振荡在原核形成前后停止。精子Ca^2+释放活性定位于雌、雄原核。2）探讨了锶诱导小鼠孤雌激活的最佳条件，并对激活卵母细胞的发育能力进行了评价。在来自B6 CBF 1小鼠的卵母细胞中，超过90%的卵母细胞通过用锶处理30分钟而被激活，形成第二极体和单个原核。二倍体孤雌胚胎发育成囊胚的能力得到提高; 93%的胚胎发育到囊胚阶段，11%的胚胎发育到妊娠第10天。这些数据清楚地表明，锶是一种有效的刺激，诱导小鼠卵母细胞孤雌激活。3）重复电脉冲对受体卵母细胞和供体卵裂球的影响进行了研究在核移植牛胚胎的发育。一系列重复的电脉冲（间隔30 min）可提高体外成熟卵母细胞的激活率和原核形成率。与供体核融合后，超过20%的重构胚胎在体外发育为囊胚期。在与供体卵裂球和受体卵母细胞融合之前，额外的电脉冲显著提高了发育成囊胚的重构胚胎的百分比（38%）。这些结果表明，一系列重复的电脉冲可以诱导牛卵母细胞的可口激活，促进核移植胚胎的发育。

The present study was conducted to examine the effects of intracellular calcium on embryo development in mammals.1) Intracellular Ca^<2+> concentrations of oocytes fertilized in vitro were monitored continuously starting from at fertilization to the end of the oscillations. The data showed that intracellular Ca^<2+> oscillations were stopped around the time of pronuclear formation, 3-4 hours after insemination. Sperm derived Ca^<2+> releasing activity was localized into both male and female pronuclei.2) The optimal conditions for inducing parthenogenetic activation by strontium were examined and the development ability of the activated oocytes was accessed in mice. In oocytes derived from B6CBF1 mice more than 90% of oocytes were activated by the treatment with strontium for 30 min, forming the second polar body and a single pronucleus. The ability to develop to blastocysts was improved in diploid parthenogenetic embryos ; 93% were developed to the blastocyst stage and 11% of the embryos developed to day 10 of gestation. These data clearly showed that strontium is a potent stimulus for inducing parthenogenetic activation in mouse oocytes.3) The effect of repetitive electrical pulses to recipient ooplasts and donor blastomeres on the development was examined in the nuclear transferred bovine embryos. A series of repetitive electrical pulses with 30 min intervals improved the rates of activated oocytes and the pronuclear formation in oocytes matured in vitro. After fusion with a donor nucleus, more than 20% of the reconstituted embryos developed blastocyst stage in vitro. Additional electrical pulses before fusion to the donor blastomeres and recipients ooplasts significantly enhanced the percentage of reconstituted embryos developing to the blastocysts (38%). These results suggest that a series of repetitive electrical pulses can induce palatable oocyte activation and enhance the development of nuclear transferred bovine embryos.