Analysis of development and differentiation suppression mechanism in the tetraploid mouse embryos

有丝分裂抑制或早期发育阶段的细胞融合在哺乳动物中产生四倍体胚胎。然而，这些胚胎无法发育到足月，也永远无法生育活的幼仔。四倍体细胞在体外存活并维持，但细胞不能形成活的胎儿。它们发育的失败被认为取决于细胞大小的增加，这导致新陈代谢不足和细胞周期延迟。在目前对细胞松弛素B诱导的四倍体小鼠胚胎的研究中，直接证实了四倍体细胞周期的延迟，尽管桑葚胚和胚泡格式化像正常的二倍体胚胎一样按时进行。继续有丝分裂抑制会产生巨大的细胞核和细胞内2至4个的多核。对于多倍体的分析，我们使用直接R显带FISH方法进行细胞周期的间期，这与有丝分裂期的核型分析不同。通过这种方法，来自 MHC H 类区域的 BAC 克隆的信号被发现为二倍体中的 2 个单点和四倍体中的 4 个单点。这表明直接R显带FISH方法是区分interp碱基中染色体重复的有用技术。为了追踪胚胎发生过程中的二倍体和四倍体细胞，利用绿色荧光转基因小鼠制备了嵌合小鼠。两种细胞谱系在紫外光下都很容易被识别，在 GFP-Tg 小鼠衍生细胞中呈绿色荧光。对二倍体和四倍体胚胎之间的嵌合进行分析的结果是，四倍体来源的细胞主要构成胚胎外组织，例如胎盘和胚胎膜，与构成胚胎的非倍体来源的细胞相反。上述通过有丝分裂抑制得到的四倍体的结果与通过电细胞融合得到的四倍体的结果不同。 '应进一步详细研究有丝分裂抑制和细胞融合产生的四倍体的差异。较少的

Mitosis prohibition or cell fusion at early developmental stage produces the tetraploid embryos in mammals. However, these embryos can not develop for full term of gestation and never deliver living young. The tetoploid cells survive and are maintained in vitro, but the cells can not form living fetus. The failure of their develop ment are considered to depend on increment of the cell size which results in insufficiency of metabolism and delay of cell cycles. In the present study of the tetraploid mouse embryo induced by cytochalsin B, the delay of tetra ploid cell cycles were confirmed directly in spite of the morula and blastcyst formatidh is performed on time as normal deploid embryos. And continuation of mitosis prohibition produced enormously large nucleus and multi nuclei from 2 to 4 in a cell. For the analysis of the polyploidy, we used the direct R-banding FISH method for the interphase of cell cycle, unlike karyotype analysis at the mitotic phase. By this method the signal of … More BAC clone from MHC class H area was found as 2 single dots in deploid and 4 single dots in tetraploid. It shows that the direct R-banding FISH method is a useful techniques for distinction of chromosomes duplication in interp base. For the trace of the deploid and tetraploid cell during embryogenesis, the chimeric mouse were made using green fluorescent transgenic mouse. Both cell lineages were readily identified under the uv lihgt, as green fluorescent in the GFP-Tg mouse derived cell. As a result of the analysis of chimra between deploid and tetra ploid embryos, tetraploid derived cells composed mainly the extraembryonic tissue, such as placenta and embryonic membrane, in contarast to the deploid derived cells contributed to the embryos. Above mentioned results from the tetraploidy by mitosis inhibition were differ from the tetraploidy by the electric cell fusion. 'The further study should be performed on the difference of tetraploidy between by mitosis inhibition and cell fusion in detail. Less