细胞核

Amitosis began with a transversal constriction of nucleus to form dumb bell shaped nucleus which later split into two daughter nuclei, and completed with the separation of cytoplasm to form two new cells.

无丝分裂过程先是细胞核中部缢缩形成哑铃状细胞核，然后分裂成两个子细胞核，最后细胞一分为二、完成细胞分裂。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cytoplasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methylation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribution of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cyto-plasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methy-lation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribu-tion of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastcysts fellowed by fusion of cytoplasm and nucleus and cleavage in vitro.After fusion of cytoplasm, the DNA methylation levels of the fused embryos was very high as well as two-cell diploid embryos in vivo.Then the embryos was rapiddly demethylated when the nucleus begin to fuse, resulting the lowest DNA methylation levels when the nucleus fused completely.After that, the DNA methylation levels of fused embryos were gradually increased until the blastocysts stage.However, whereas an asymmetric distribution of DNA methylation was established in an vivo-derived blastocysts with a higher methylation level in the inner cell mass than in the trophectoderm, in most vitro-derived tetraploid blastocysts, we can not detect the asymmetric distribution.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在囊胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Some investigations suggested that cyclins and CDK played an important role in the regulation of endomitosis of megakaryocyte. However, the mechanism of cyclins and CDK in the regulation of endomitosis of fetal megakaryocytes during ontogenesis and the relationship between cyclins/CDK and retardation of endomitosis of fetal mgakaryocyte is totally unknown.

一些研究发现周期蛋白和CDK在巨核细胞核内有丝分裂的调控上起重要作用，然而，周期蛋白和 CDK在胎儿巨核细胞核内有丝分裂调控上所起的作用，及其与胎儿巨核细胞核内复制延迟的关系目前全然不知。

The major factors affected the efficiency of goat embryo nuclear transfer technique were discussed systematically in this study in order to establish an acceptable manipulation and production system of embryo nuclear transfer technique in our lab.

本研究系统的探讨了山羊胚胎细胞核移植过程中的几个主要影响因素，以期完善山羊胚胎细胞核移植操作程序和胚胎细胞核克隆胚胎生产体系。

Thirdly,The nuclear chromatin of lung carcinoma cells concentrate to periphery, the electron density of cytoplasm increased, in some cells,the heterochromatin of nucleus were blurry,and the nucleole became uniform in electron density, the formatio reticularis of nucleole disappeared.

细胞核的改变：细胞核内染色质边集，基质电子密度增高。有些细胞核内异染色质分界不清，核仁呈均一电子密度，网状结构消失。

With DGD method, the electron microscopy observation has provided new information on the process of chromatin migration. That is: Firstly, the nucleus moved toward cell wall and a picture characteristic of synizesis stage of meiosis appeared; Secdonly, the transmigration of chromatin occured through CC, and a more extensive region constituted of nuclear skeleton left behind chromatin, which was named as"clear spaces" under light microscopy; Thirdly, at the late stage of synizesis, most of chromatin had gone into adjacent cells through CC and fused into a whole, and the nuclear skeleton left in the former cell gradually mixed with cytoskeleton in cytoplasm.

DGD—包埋去包埋电镜观察表明：百合花粉母细胞中有类似核纤层的结构存在；在染色质穿壁运动过程中，首先是细胞核向细胞壁靠拢，并可留下瞬间的运行轨迹——细胞核后方出现只有细胞骨架而少有细胞器的区域；其后是染色质开始穿壁，在穿壁染色质后方细胞核内出现无染色质仅有密集的核骨架的区域，到了染色质穿壁后期，大部分核物质都已穿至相邻细胞，并彼此融合，而残余在原穿出细胞中的核骨架己逐渐与原细胞的胞质骨架融为一体。

Figure 6 Bright fluorescence of condensed nuclear chromatin appeared around circumnuclear edge of apoptotic osteoclast,nonapoptotic nuclear fluorescence showed coherent distributed.

凋亡细胞核核周呈一亮环，而未凋亡细胞核染色均一（图6）。图6 凋亡破骨细胞胞核周缘呈环状亮色，而未凋亡细胞核荧光染色均一。

The nuclear image messages were digitalized and stored in the computer to form a database available for further study in this field. Results (1) In the EL, the majority were the big global nuclei of the mature ependymal cells. A few bigger nuclei were located deep to the ependymal cells, and some small irregular-shape, nuclei were scattered and wedged between ependymal cells.

结果 ①在EL，主要是体积较大且呈球形的成熟室管膜细胞核；另有体积更大的球形细胞核贴近室管膜细胞深方；此外，还有体积较小而形状不规则的细胞核散在镶嵌于室管膜细胞之间。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。