细胞分裂

Amitosis and asymmetric division play an important role in PC12 cell pleomorphism. The asymmetric division possesses important significance in tumorigenesis and differentiation.

无丝分裂和不对称分裂是PC12细胞多形性形成的主要原因，肿瘤细胞无丝分裂及其不对称性对肿瘤发生及肿瘤细胞的分化具有重要意义。

Cell cycle is the cell through a series of orderly changes in the cells to achieve cell growth and proliferation process of cell cycle regulation and individual development, differentiation, growth, regeneration, aging and cancer cells is closely related to eukaryotic cell cycle mitosis two key processes, namely DNA replication and sister chromatid evenly assigned to the sub-cells.

细胞周期是指细胞通过一系列有序的细胞内变化，实现细胞生长和分裂增殖的过程细胞周期的调控与个体发育、分化、生长、再生、衰老以及细胞的癌变密切相关真核细胞有丝分裂周期有两个关键的过程，即DNA的复制和姐妹染色体均衡地分配到子细胞中。

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。

DMBQ, ferulic acid and resorcin were effective chemical signal substances in the process of seed germination and haustorium formation of Cistanche deserticola. 4.The embryo is consist of 12 cells, the endosperm cell degraded so as to provide nutrition for the embryo development .As a result, germ tube differentiated from the embryo and came out through micropylar end, the small cell at the tip of the germ tube held the capacity of cleavage and the other cells grew big ,so the germ tube elongated .The anterior extremity of germ tube swelled to form haustorium under chemical substances treatment, the haustorium cell stained ,especially its portrait because of the lignification of the cells.

肉苁蓉种子的胚是由12个细胞紧密排列形成的圆球状胚，球形原胚分裂增殖的同时，胚乳细胞分解，为胚细胞的增殖提供营养，最终胚上分化出的芽管由珠孔端冒出，芽管前端细胞较小，具有旺盛的分裂能力，后部细胞体积增大，芽管逐渐伸长，在化学物质的诱导下，芽管由中部至前端细胞膨大分化出初生吸器，初生吸器呈帽子状，而这些细胞比其周围的细胞着色深，吸器纵向局部区域的番红染色加深，细胞高度木质化。

Megaspore mother cell just enters leptotene as The meiosis of microspore mother cell develop into tetrads . The meiosis of megaspore mother cell develop into pachytene while that of microspores develop into a single nuclear adjacent to cell wall.

当白杨小孢子母细胞减数分裂至四分体时，大孢子母细胞开始进入减数分裂细线期；而当小孢子发育至单核靠边期上时，大孢子母细胞减数分裂达到粗线期。

Our study includes four aspects. In the first aspect we study several important conditions of porcine oocytes maturation in vitro and oocytes cleavage after parthenogenetic activation and found mNCSU-23+15IU/mlPMSG+20IU/mlHCG+15% PFF+0.57mMcysteine is a good culture condition .When the Cocs are cultured in it ,the maturation rate and oocytes cleavage rate are higher than those of foreign covered. Our result are (86.7±3.35)% and (86.3±4.16)% and the highest report of foreign is(85.7±4.1)%.In the second aspect we study the effect of different chemical activations on development of porcine parthennogenetic embryo and found two best activation method. The first one is that putting the maturation MII oocytes in the 20μmol/L ionomycin for 30 minutes and then putting them in the NCSU-23 condition containing 5μg/mICB and 5mM/L6-DMAP for 3.5 hours, the oocytes cleavage rate and morulae/blastocysts development rate are (76.7±7.6)% and (37.1±6.4)%.The second one is that putting the maturation MII oocytes in the 200μM/L Thimerosal for 20 minutes and then putting them in the NCSU-23 condition containing 8mM DTT for 30 minutes

本研究分为4个部分，第一部分对影响猪卵母细胞体外成熟和孤雌激活后胚胎分裂的几个重要条件进行了比较研究，确立了一种较好的培养方法：与颗粒细胞共培养，找到了一种适合猪卵母细胞体外成熟的培养基：mNCSU-23+15IU/mlPMSG+20IU/mlHCG+15%PFF+0.57mM半胱氨酸，成熟率和分裂率分别为(86.7±3.35)%和(86.3±4.16)%，国外报道的最高成熟率为(85.7±4.1)%；第二部分对猪卵母细胞孤雌激活的化学方法进行了研究，确立了化学激活猪卵母细胞的两种最佳方法：1将成熟的去卵丘颗粒细胞的MII期卵母细胞用20μmol/Lionomycin作用30min，再将卵母细胞培养于含5μg/mlCB和5mM/L 6-DMAP(6-二甲基氨基嘌呤)的NCSU-23培养液中，卵裂率和桑囊胚发育率达到(76.7±7.6)%和(37.1±6.4)%2将成熟的去卵丘颗粒细胞的MII期卵母细胞在200μM/L的Thimerosal中处理20min，再与8mM的DTT共孵育30min，卵裂率和桑/囊胚形成率为(81.0±2.8)%和(39.6±2.7)%；第三部分对孤雌激活胚胎的培养条件进行了研究，确立了一种最佳的胚胎培养条件：在SOF简单培养基中添加颗粒细胞进行前3天的培养，然后转入添加胎牛血清的NCSU—23培养基并和输卵管上皮细胞进行后期的培养，其桑椹胚和囊胚的发育率为(59.5±3.2)%；第四部分研究了IGF-I

Insulin-like growth factor I and II, which are mitoses,acting through type 1 IGF receptor, have mitogenic and anti-apoptotic effects on many kind of cells, also on epithelial and stromal prostatic cells.

胰岛素样生长因子I和II均为强有丝分裂源，通过与胰岛素样生长因子I类受体结合，对多种细胞发挥促有丝分裂及抗细胞凋亡作用，同样对前列腺基质及上皮细胞具有促有丝分裂及抗细胞凋亡作用。

The meiosis of oocytes differ from mitoses of general cells. Especially in most mammalian species, oocytes are formed during fetal life, but they are arrested at the prophase stage of the first meiotic division until around the time of ovulation.

卵母细胞的成熟分裂有别于一般细胞的有丝分裂，尤其是哺乳动物，在胎儿期或出生后不久，初级卵母细胞就陆续进入第一次成熟分裂前期阶段，但长时间的&休止&于此期，直到性成熟时在促性腺激素等因素的作用下，第一次成熟分裂才重新启动。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。