核分裂

The ultrastructural changes during the development of sieve element companion cell complex (SE/CC complex) in Populus deltoides were investigated using electronic microscopy. The result showed that SE and CC tome from the same secondary phloem mother cell. The development of sieve element went through three stages, i. e. immature, mature, and degenerate stage. In immature stages the sieve element presented radial expansion, cell wall thickening, and production of sieve plastid and P-protein. The cytoplasma selectivly autolysed in mature stage. At the same time, karyoplasm was dispersed, and nuclear envelope was not clear, or karyoplasm was disorgnized, and nuclear envelope was clear. The karyopalsm finally turned into P-protein. In degenerate stage, the cytoplasm completely disappeared, and the function was lost.

利用电镜技术研究美洲黑杨次生韧皮部筛管和伴胞发育过程中细胞超微结构的动态变化，观察到筛管和伴胞由同一个次生韧皮部衍生细胞分裂分化形成筛管约发育历经未成熟期、成熟期和衰退期的变化未成熟期筛管分子表现为细胞的径向扩展、壁的增厚、筛管质体和P-蛋白质的产生；成熟期筛管分子细胞组分发生选择性自溶，细胞核核质弥散状，核膜不清晰，或核膜清晰而核物质降解，最后细胞核完全解体转化为P-蛋白质类的物质；衰退期筛管分子细胞质完全解体消失，失去功能。

However, as the concentration increased to 100~400μg/mL, the micronucleus ratio significantly rose, while the karyokinesis index significantly decreased.

浓度升高到100~400μg/mL时，细交链孢菌酮酸使蚕豆根尖细胞微核率显著升高，有丝分裂指数显著下降，其中，400μg/mL时，微核率高达36.01‰，有丝分裂指数仅为1.90%。

Reduction division The first division of meiosis , including prophase, metaphase I, and anaphase I. It results in a haploid number of chromosomes gathering at each end of the nuclear spindle.

减数分裂：减数分裂中的第一次分裂，包括分裂前期，中期 I 和后期 I ，形成单倍数目的染色体在每一个核纺锤体末端聚集。

The samples were smeared on slides and stained with Giemsas stain. The stained smears were observed microscopically and photographed. It showed that except typical trophozoites in binary fission. the following trophozoites of abnormal morphs were also observed. for instance abnormal trophozoites with binary fission; enlarged trophozoites with round and irregular shaped eosinophilic bodies in the cell plasma; enlarged cells containing round and irregular shaped eosinophilic bodies and flagella; enlarged cells which contain 6 or 8 nuclear-like bodies and flagella, 3 or 4 embryonic forms of daughter trophozoite in one mother trophozoite; 4 trophozoite embryonic forms with fused plasma 3 trophozoites with fused plasma;4 trophozoites with fused plasma; a pair of trophozoite with binary fission fused with another trophozoite;2 pairs of trophozoite with binary fission fused each other; a trophozoite with 1 nuclear only.

结果 除观察到典型的营二分裂法繁殖的贾第虫滋养体外，还可见到多种形态异常的虫体，包括；虫体呈非典型二分裂；滋养体胀大，胞质中有团块状和不规则形状的嗜酸性物质；在胀大的贾第虫细胞内含有团块状和不规则形状的嗜酸性物质以及鞭毛；在胀大的贾第虫细胞内含有6或8个核状物以及鞭毛；在一个母体细胞中含有3或4个子体细胞的雏形；胞质互相融合的4个滋养体的雏形；胞质互相触合的3个滋养体，胞质互相融合的4个滋养体；1对营二分裂的滋养体与另一个滋养休互相融合；2对营二分裂的滋养体互相融合；仅有1个细胞核的滋养体。

It is the first time that these phenomena were observed: Two nuclei are surrounded by plasma and locate at the central of the female gametophyte and the others nuclei are positioned at the fringe of the female gametophyte; Before the pollen tube enters the female gametophyte. the nuclei in chalazal end begin splitting of plasma and form multinuclear cell.4. The pollens of Gnetumc are spherical or applanate with single aperture. The ornamentation of exine is spine. The basis part of spine is lenience and the top part of spine is tip or obtuse sphere.

首次在买麻藤属植物的雌配子体中观察到2个游离核位于配子体的中央位置，且被一团原生质所包围的，其余的游离核位于边缘的现象以及花粉管进入雌配子体前，合点端的核已经发生胞质分裂形成多核细胞的现象 4、买麻藤的花粉近球形或扁平型，有单萌发孔，外壁表面具小刺状纹饰，小刺基部宽大，末端尖或钝圆。

In conclusion, these results suggested that (1) the ageing-associated decline in fertility of female KM mouse was due to a decrease in both quantity and quality of oocytes;(2) the ooplasm from young mice did not correct the meiotic errors of aged mice, and the ooplasm from aged mice did not induce abnormal segregation of meiotic chromosome of young mice, indicating that meiotic anomalies found in the oocytes of aged mice might be related to nucleus or chromosomes and relevant factors;(3) a critical nucleocytoplasmic ratio was essential for normal maturation and segregation of meiotic chromosomes of oocytes and development to 2-cell embryos.

本研究结果表明：（1）昆明白小鼠与衰老相关的生育力下降是其卵母细胞数量减少和质量下降的综合结果；（2）年轻小鼠卵母细胞细胞质不能纠正老龄小鼠GV的减数分裂错误，老龄小鼠卵母细胞细胞质也不诱导年轻小鼠的GV发生减数分裂错误，老龄小鼠卵母细胞减数分裂异常很可能与细胞核或染色体及其相关因素有关；（3）关键的核质比对卵母细胞正常的成熟、减数分裂染色体分离及2-细胞期胚的发育是绝对必需的。

Most of the a-sexual embryo sacs also parthenogenetically developed into asexual seeds,which is the same as that of their maternal parent.

此外，平邑甜茶也形成次生极核，并在卵分裂前，形成胚乳游离核；而卵的发育，无论受精与否都要经过3-5天休眠后分裂，并逐渐形成小球形胚、子叶胚。

The situation of abnormal development of male cells is as follows:microspore mother cell can't enter into meiosis because of intense vacuolation,shrink and disintegration of its cytoplasm;although vacuolated microspore mother cell can enter into meiosis,it can't form normal dyad and degenerate in the middle process;dyad and tetrad become vacuolated and can't develop normally;cytoplasm of microspore shrinks around the nucleus at the stage of central nucleus microspore,the shape of microspore is twisted into crescent or irregular shape,at last its cytoplasm and nucleus are disintegrated and crescent vacant microspore presents;nutritive substances can't be accumulated at the stage of vacuolated microspore,cytoplasm is disintegrated,and microspore turns into a big vacant pollen.

雄性细胞异常发育有几种情况：小孢子母细胞强烈液泡化，细胞质收缩解体，不能进入减数分裂；小孢子母细胞液泡化，虽能进入减数分裂，但不能形成正常二分体而中途退化；二分体、四分体细胞液泡化，不能进行正常发育；单核小孢子中央期，细胞质收缩包围核，小孢子形状扭曲呈月牙形或不规则形，最终细胞质和核解体而呈月牙形的空壳小孢子；单核液泡期的小孢子不能积聚营养物质，细胞质解体而成为大的空壳花粉粒。

Megaspore mother cells undergo meiosis, which results in the formation of 4 megaspores in a row. The chalazal-most cell develops into an 8-nuclei embryo sac after 3 rounds of mitosis. A mature embryo sac is produced after cellularization and nuclear migration.

结果表明：1大孢子母细胞经过减数分裂形成直线排列的4个大孢子，其中珠孔端的3个大孢子退化，合点端的大孢子进行3次有丝分裂，形成八核胚囊， 8个核迅速细胞化，最终发育为成熟胚囊。

For transgenic mice,98%~100% of metaphases and 85%~94% of interphases showed hybridization signal.For negative control mice,100% of metaphases and 95%~96% of interphases showed no hybridization signal.

阳性转基因小鼠98%~100%的中期分裂相，85%~94%的间期核出现杂交信号；阴性对照小鼠100%的中期分裂相、95%~96%的间期核未出现杂交信号。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。