减数性

Meiotic pachytene bivalents were obtained from porcine testes using prolonged hypotonic treatment combined with high chloroform Carnory's fixative solution. Mitotic metaphase chromosomes were prepared from blood cell culture. Comparative studies on division index and length of pachytene bivalents and mitosis metaphase chromosomes showed that those of the former are 5 times higher and 3.42(1.87～5.98) times longer than the latter, respectively. Chromomere maps of bivalents are more abundant than mitotic metaphase G-bands, while they are correspondent with mitotic early-metaphase G-bands. The result was found by using the chromosome 12 as a sample.

以性成熟公猪睾丸和外周血为材料，采用长低渗、高氯仿卡诺固定液固定和外周血细胞培养制备减数分裂粗线期二价体和有丝分裂中期染色体，通过对二价体和有丝分裂中期染色体分裂指数和长度的比较研究，发现二价体的分裂指数和长度分别是有丝分裂中期染色体的5倍和3.42倍(1.87～5.98)；同时以12号染色体为例，比较了二价体上的染色粒结构带与有丝分裂中期染色体G-带，表明染色粒结构带比中期染色体G-带带纹丰富，而与早中期G-带带纹吻合。

To investigate whether the expression of cdc2 and cyclin B1 in spermatogenic cells during spermatogenesis is actually a temperature dependent event, in situ hybridization, Western blotting and immunohistochemistry analysis were used to study the expression of cdc2 and cyclin B1 in normal and cryptorchid testis. Results showed that heat would differentially hurt male germ cells in different developmental stages during spermatogenesis, especially the pachytene primary spermatocytes. Most of spermatogonia in contralateral cryptorchid testis were not harmed fatally by heat as yet, indicating that spermatogonia could resist to beat to a certain extent. In this case spermatogonia could develop to pachytene/diplotene primary spermatocytes, but they could not acquire the ability to complete the transition from mitosis to meiosis, and then appeared to go through apoptosis. Therefore, we could not find the descendants of meiosis: secondary spermatocytes and round spermatids, elongated spermatids and spermatozoon. The abdominal temperature had no significant influence on the transcription of cdc2 and cyclin B1 in the spermatogonia and pachytene/diplotene primary spermatocytes. In normal rabbit testis, cyclin B1 increased in the pachytene/diplotene primary spermatocytes before meiosis and reached its peak in the spermatids.

为了解精子正常发生过程中cdc2和cyclin B1表达的低温依赖性，我们利用原位杂交和免疫组化等方法，研究了正常和隐睾精子发生过程中cdc2和cyclin B1的转录和翻译调控活动，结果表明：（1）热对各阶段的雄性生殖细胞都有损害，粗线期的初级精母细胞尤为敏感，实验性隐睾内的精原细胞尚未完全受到"致命"影响，说明精原细胞对热有一定的耐受性，但即使成为粗线期／双线期初级精母细胞，却未能获得由有丝分裂过渡到减数分裂的能力，呈现不同程度的凋亡，所以在整个切片中找不到源自减数分裂的产物----次级精母细胞、圆形精子细胞，更谈不上长形精子细胞和精子的形成；（2）腹腔高温未明显地影响隐睾精原细胞和粗线期/双线期初级精母细胞中cyclinB1和cdc2的转录，说明高温并不是通过影响cyclin B1和cdc2的转录活动而导致生精过程阻断的；（3）正常兔睾丸组织中，〓在精原细胞和粗线期／双线期精母细胞中均有表达：cyclin B1蛋白在减数分裂前期的粗线期／双线期初级精母细胞中的表达量增加，于变态末期的精子细胞中达高峰。

Results indicated : The meiosis stages of megaspore of white poplars are different, while there was a association between MMCs and PMCs meiosis in the same hybrid.

研究表明，不同白杨的大孢子母细胞减数分裂进程存在差异性，而同一树种的大、小孢子母细胞减数分裂进程存在时序性相关。

Now the research has made progress.(1) The meiosis stages of megaspore could be discriminated timely through observing the meiosis of microspore under the same environmental conditions, according to the association of female and male buds during development.

1首次提出利用雌、雄花芽发育进程的时序性相关性，以相同生境以及培养条件下的小孢子发育进程为参照，从而相对准确地实现白杨大孢子母细胞减数分裂进程即时判别的技术方法。

It was thought that space induction caused the variation of size, fertility and the abnormal meiosis.

分析认为花粉的大小差异和花粉的育性与减数分裂异常有关，而这些现象都是航天诱变造成的

The development of Peiai 64S and IR36 did not differ up to microsporocyte formation stage; but since meiosis stage, male reproductive cells of Peiai 64S underwent several structural changes and ultimately terminated by early bicellular stage.

结果表明，小孢子母细胞减数分裂之前，培矮64S与IR36的发育过程基本相似。但从减数分裂开始，培矮64S的雄性性细胞出现一些异常变化，并最终发育至二胞花粉早期败育。

At time of 5mm length of alabatrum, the miosis in microsporecyte and the sex differentiation was found, thus in female flowers, pollen mother cell showed a abnormal meiose then the pollen cells gradually disintegrated, final, contabescence had taken, and in male flowers, the stamen normally developed.

在幼蕾长到5mm左右，即花粉母细胞开始减数分裂时，出现花性别的分化，雌花中雄蕊花粉母细胞不能进行正常减数分裂，进而花粉细胞逐步解体而导致雄蕊败育；雄花中雄蕊发育正常至性成熟。

2N gametes are the result of meiotic mutation during micro- and mega-sporogenesis that bear the sporophytic rather than the gametophytic chromosome number. This paper reviewed the genetic markers including the morphologic, cytological, isozymes and DNA markers, which have been employed in the generation, inheritance, heterozygosity and marker-assisted breeding of 2n gametes based on the frequency of large pollen grains, cytological analyses, unexpected occurrence of polyploidy progeny and the associations between parents and progenies.

文章综述了植物2n配子发生及其遗传标记研究现状，论述涉及有关形态学标记、细胞学标记、同工酶标记乃至DNA标记等遗传标记在2n配子研究中的应用，指出通过花粉形态观察、大小孢子母细胞减数分裂行为观察、杂种后代倍性鉴定以及亲子分子标记相关分析等，对2n配子发生、2n配子遗传类型与杂合性以及2n配子在育种实践中的有效性等进行研究。

Thus it is obvious that the weak homology existedamong genomes A, B, D and 〓. However, the rare unreduced gemetes and near-unreduced ones with the loss of several chromosomes could be produced by the highlyunequtional division of univalents at the first meisis and the normal second division,which gave the F1 hybrid the partial fertility.

但通过第一次减数分裂时单价体的极不对称的分离及正常的第二次分裂，可形成少量未减数配子和丢失了少数几条染色体的近未减数配子，使杂种〓表现部分可育性。

For further studying the genetic mechanism of the reproductive isolation phenomenon of interspecific hybrid, paraffin sections of testes from 13 sexually mature male mules (Equus asinus×Equus caballus) and 12 hinnies (Equus caballus×Equus asinus) were prepared, and the samples of Giemsa meiosis and AgNO 3 synaptonemal complexes were observed and compared with spermatocyte meiosis of horse and donkey under light microscope and electronic microscope.

为了进一步探讨种间杂种生殖隔离现象的遗传机理，本研究采用性成熟公骡的睾丸为材料，制备组织切片和减数分裂联会复合体标本进行观察，发现个别性腺发育较好的个体虽然减数分裂存在大量异常，但确有少数精母细胞完成了减数分裂并产生精子。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。