Somfai Tamás, Inaba Yasushi, Aikawa Yoshio, Ohtake Masaki, Kobayashi Shuji, Konishi Kazuyuki, Imai Kei
National Livestock Breeding Center, Fukushima, Japan.
J Reprod Dev. 2010 Apr;56(2):200-7. doi: 10.1262/jrd.09-097a. Epub 2009 Dec 25.
This study was conducted to study the kinetics of initial cell divisions in relation with the cleavage patterns in viable (with the ability to develop to the blastocyst stage) and non-viable bovine embryos and parthenotes. The kinetics of in vitro development and cleavage patterns were observed by time lapse cinematography. The length of the first and second but not third cell cycle differed significantly between the viable and non-viable embryos after IVF or parthenogenesis. Viable embryos had significantly shorter first and second cell cycles than non-viable ones. The presence of fragments, protrusions and unequally-sized blastomeres was associated with an extended one-cell stage and reduced ability to develop to the blastocyst stage; however, the lengths of the second and third cell cycles were not altered. Oocytes showing direct division from one cell to 3 or 4 blastomeres showed similar developmental ability and embryonic cell numbers to those showing normal division, although, with a high frequency of chromosomal abnormalities. Our results suggest that the differences in the first cell cycles between viable and non-viable embryos were not sperm-related, whereas direct cleavage of 1-cell embryos to 3 or more blastomeres and protrusion formation are related to sperm-driven factors. The length of the first and second cell cycles and the cleavage pattern should be examined simultaneously to predict developmental competence of embryos at early cleavage stages.
本研究旨在探讨活的(有能力发育至囊胚阶段)和非活的牛胚胎及孤雌胚胎初始细胞分裂动力学与卵裂模式之间的关系。通过延时摄影观察体外发育动力学和卵裂模式。体外受精或孤雌生殖后,活胚胎和非活胚胎的第一次和第二次而非第三次细胞周期时长存在显著差异。活胚胎的第一次和第二次细胞周期明显短于非活胚胎。碎片、突起和大小不均等的卵裂球的存在与延长的单细胞阶段以及发育至囊胚阶段的能力降低有关;然而,第二次和第三次细胞周期的时长并未改变。显示从一个细胞直接分裂为3或4个卵裂球的卵母细胞,其发育能力和胚胎细胞数量与显示正常分裂的卵母细胞相似,不过染色体异常频率较高。我们的结果表明,活胚胎和非活胚胎之间第一次细胞周期的差异与精子无关,而1细胞胚胎直接分裂为3个或更多卵裂球以及突起形成与精子驱动因素有关。应同时检查第一次和第二次细胞周期的时长以及卵裂模式,以预测早期卵裂阶段胚胎的发育能力。