孢子母细胞

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。

In theterosporous species, a distinction is usually made between megaspore mother cells and microspore mother cells.

在异型孢子体种类中，可区分为大孢子母细胞和小孢子母细胞。

In seed plants also produce spores, and spores are profiled in the ovule Pearl hearts a megaspore mother cell produces large spores by meiosis in the anthers of the microspore mother cells produced by meiosis of microspore.

在种子植物中也产生孢子，且均为孢子异型，在胚珠的珠心中的1个大孢子母细胞经减数分裂产生大孢子，在花药中的小孢子母细胞经减数分裂产生小孢子。

The megaspore mother cell is located at the 3rd or 4th layer of cells in the nucellus top end. It divides transversally to form a linear megaspore tetrad, and the megaspore at the chalazal end develops into the embryo sac mother cell.

大孢子母细胞位在珠心顶表皮下第三或四层细胞处，经横分裂后产生一直线形的大孢子四分体，其中位居合点端的大孢子发育成胚囊母细胞。

The primary sporogenous cells divided into the second sporogenous cells which would turn into microspore mother cells in a microsporangium. The cytokinesis in meiosis of the microspore mother cells was of modified simultaneous type, forming the decussate, isobilateral or T-shaped tetrads.

初生造孢细胞分裂形成次生造孢细胞，次生造孢细胞再转化为小孢子母细胞，小孢子母细胞减数分裂的胞质分裂为修饰性同时型，四分体排列方式为交叉型、对称型或"T"型，成熟花粉粒二细胞型，开花时散出。

The observation showed that sterile plants and fertile plants in the pollen mother cell stage is not very different, when microspore mother cells of male sterile plants enter meiosis period, it could form normal tetrad cell , tetrad cell is normal in early development stage, In the uninucleate microspore stage , tapetal cells were vacuolization, the microspores were extruded to the middle by tapetal cells.

本研究利用石蜡切片法，结合光学显微镜技术对樱桃萝卜核质互作雄性不育系的不育株和对应保持系可育株的花药发育过程进行细胞形态学观察，观察结果表明：不育株与可育株在花粉母细胞时期差别不大，不育株的花药小孢子母细胞进入减数分裂期后，可以正常的形成四分体，四分体前期发育正常，而在单核小孢子期绒毡层细胞出现液泡化，绒毡层细胞向中间挤压小孢子。

The results show that the normal process begins with archesporial cell and undergoes stages of primary and secondary sporogenous cell,microspore mother cell,dyad,tetrad,central nucleus microspore,vacuolated microspore,mature microspore,twocell pollen and threecell mature pollen.

对平流层辐射处理SP3谷子和对照CK3谷子雄性细胞发育的研究表明，雄性细胞正常发育过程从孢原细胞开始，经初生造孢细胞、次生造孢细胞、小孢子母细胞、二分体、四分体和单核小孢子中央期、单核小孢子液泡期、单核小孢子成熟期直到二细胞花粉、三细胞成熟花粉结束。

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。

The primary sporogenous cells divided into the second sporogenous cells which would turn into microspore mother cells in a microsporangium. The cytokinesis in meiosis of the microspore mother cells was of modified simultaneous type, forming the decussate, isobilateral or T-shaped tetrads.

初生造孢细胞分裂形成次生造孢细胞，次生造孢细胞再转化为小孢子母细胞，小孢子母细胞减数分裂的胞质分裂为修饰性同时型，四分体排列方式为交叉型、对称型或&T&型，成熟花粉粒二细胞型，开花时散出。

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。

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。