减数分裂

The reproductive development process of birch was described as follows: Male inflorescences extended from apical bud in early June. In later June, stamen primodium was differentiated in the bract of male inflorescence and the differentiation of bract was generated in female inflorescence. During July, anther layers and archesporial cell were differentiated in anther, then archesporial cell developed into mother microspore cell. Pistil primodium came into being at the same time. In early part of August the meiosis of mother microspore cell started. In later August, mono-nucleus microspore was formed. After September, both male inflorescence and female inflorescence were dormant.

白桦的生殖生长发育过程如下：6月初，雄花序从顶芽中生长出来。6月中下旬，雄花序苞片上分化出雄蕊原基，雌花序分化出苞片。7月，雄花花药分化出花药壁和孢原细胞，孢原细胞演化为小孢子母细胞，雌花序苞腋处分化出雌蕊原基；8月中上旬，小孢子母细胞减数分裂，8月下旬形成单核小孢子；9月后雄花序以单核小孢子状念越冬，雌花序以雌蕊原基状念越冬。

A mutant of Impations balsamina was obtained after space induction, and its traits and meiosis were investigated.

本文报道了种子经神舟 4号飞船搭载的凤仙花突变植株的性状及减数分裂过程的变化。

Whereas, the tapetum of Zhenshan 97A disaggregated at the pollen mother cell stage, the nuclear membrane and the cell membrane disaggregated, the phenomena continued to the binucleate pollen stage. The cytoplasm of the tapetum cells of Zhenshan 97A deposited a few Ca^2＋ precipitates at the pollen mother cell stage.

珍汕97A绒毡层细胞从花粉母细胞时期开始，细胞质内有少量颗粒状的Ca^2＋沉淀；减数分裂时期，绒毡层细胞的内切向壁表面有大量大颗粒的Ca^2＋沉淀；单核花粉时期绒毡层细胞周围集聚一层Ca^2＋沉淀。

Using cytohischemical staining methods, with the results of comparison the dynamics of proteins and polysaccharides in the anthe wall cells and colule cells of different developmental phases in female and male flowers, the anormogenesis of anther tapetum in the inflecting phase of from bisexual flower to unisexual flower was observed. In microspore developed phase, the tapetum functions of preserving and transportingmutritive material for microspore development and of secreting callosal enzyme for decompositing callosal cell lost no normal guadrant formed, of being abnormal meiose of pollen mother cells, and then, the stamen aborted selectively in female flowers and pistil in male flower.

利用细胞组织化学染色技术，对雌、雄花雄蕊花药壁细胞及花药内细胞发育过程中多糖及蛋白质动态进行了比较，实验中观察到雌花在从两性至单性花转变时期雄蕊绒毡层在整个发育过程中表现异常，在小孢子发育过程中未能起到贮藏、转运营养物质供小孢子发育及适时分泌胼胝质酶溶解胼胝质壁的功能，并且花粉母细胞减数分裂异常而未形成四分体结构，进而导致雌花雄蕊选择性败育，而雄花中雌蕊组织也发生了选择性败育过程。

Mature pollen grain is of 2 - celled type .

花药壁的发育为基本型，小孢子减数分裂为连续型，小孢子四分体为四面体型，成熟花粉为二细胞型。

Ovule development began in August, and rectangle megasporocyte began to occur in December, and linear tetrads of megaspores were formed in meiosis. In most occasions, only the chalazal megaspore was functional.

云南红豆杉胚珠从8月开始发生，大孢子母细胞12月开始发生，呈方形，减数分裂后形成4个&一&字形大孢子，在大多数情况下，只有靠合点端的大孢子发育为功能大孢子。

Megaspore development and abortion of"Pingyi Tiancha"Compar-ing with regular developing megaspore of normal M.baccata,the megasporemother cellof"Pingyi Tiancha"could form mono-nucleus embryo sacby perhaps irregular meiosis,then most of sexual MES depauperatedand degenerated,finally aborted,or only a few further developed.Of asexualembryo sac,one or more large cells at the chalazal end of nucellus developed in-to one to more asexual embryo sac initials.After the competition between sexu-al embryo sacand asexual embryosac,most ovules only had one asexual embryo sac matured.

平邑甜茶大孢子的发育和败育与正常发育的山定子大孢子对比，平邑甜茶大孢子母细胞经减数分裂能形成单核胚囊，之后多数有性胚囊萎缩、退化而败育，只有极少数进一步发育；而无性胚囊则从胚珠合点端1个或多个较大的珠心细脆形成并首先发育为一个或多个无性胚囊原始体；经过有性胚囊和无性胚囊以及无性胚囊和无性胚囊之间的竞争，多数胚珠只有一个无性胚囊成熟。

Morphologically, the two hexaploids are characterized by the general gigantic appearance, diagnostic of the enhancing growth in horizontal direction of such organs as leaves, stems, various compone...

它们在减数分裂时的单价体数目比三倍体显著地减少了，但另外却有少量三价体和四价体出现。

Compensatory hypertrophy is a different temporary growth response in which residual tissue increases in mass and cell number: cells undergo mitosis but do not dedifferentiate.

代偿式肥大是一个不同的，暂时的生长应答过程，残余组织在体积和细胞数量上增加：细胞经历了减数分裂，但没有去分化过程。

As there were 8.69 bivalents in average occurred to be desynaptic, moreover, the most number of the desynaptic bivalents reached 12 at post diakinsis.

从品种轮回422的群体中发现一不育单株，经细胞学观察证明是发生了联会消失突变，由于该植株的花粉母细胞在减数分裂终变期晚期平均有8.69个二价体发生了联会消失，占二价体总数的72.4%，并且发生联会消失的最多二价体数目为12，根据联会消失的最多二价体数目

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。