查询词典 tetrad

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 analysis shows that under heat stress, meiocytes degenerate while tetrad cell dispersion fails at microspore formation phase. During pollen maturation phase, loss of orientation of reproductive cells, abnormal vacuolization of tapetal cells, paramorphia or abortion of anther walls and pollens are observed under heat stress.

结果表明，受高温胁迫后，在小孢子形成阶段，水稻花粉母细胞发育异常、四分体无法适时分散；在花粉粒成熟阶段，水稻生殖细胞失去正确的排列方向、绒毡层细胞发生非正常分解、花药壁和花粉粒发生形态异常并出现败育。

Physiologically, our model estimated 2.6 days to reach the single ridge stage, 5.6d to the double ridge stage, 11.3d to the stamen and pistil initiation stage, 13.1d to the anther separation stage, 15.3d to the pollen mother cells stage and 18.2d to the tetrad stage. Phenologically, estimations were 13.1d to reach the jointing stage, 28.7d to the heading stage, 32.8d to the grain filling stage and 51.5d to the maturity stage. PDT was consequently used as a unified scale for measuring developmental progress of different cultivars under different climates and cultural practices.

经测算，各大麦品种到达单棱期、二棱期、雌雄蕊分化期、药隔形成期、雌蕊柱头二裂分叉期、雌蕊柱头毛状突起期等顶端发育阶段的生理发育时间分别为2.6、5.6、11.3、13.1、15.3、18.2、28.7d，到达出苗期、拔节期、抽穗期、灌浆期和成熟期等主要物候期的生理发育时间为0、13.1、28.7、32.8、51.5d，形成了不同大麦品种在不同气候和栽培条件下统一的衡量发育的定量尺度。

Under low temperature condition, fertility restoring, anther developing normally, the tetrads formed after archesporical cell, sporogenous cells and microspore mother cell. Subsequently, microspores were free from the tetrad of fertile anther and formed mature pollen grains, tapetumof the fertile anthers began to disintegrate and disappear at last.

在低温处理条件下，育性恢复，花药发育正常，经过孢原细胞期、造孢细胞期、花粉母细胞期后，可以顺利形成四分体，可育花药的四分体可以释放出小孢子并发育为成熟的花粉粒，同时绒毡层细胞开始解体，最后消失。

The results showed that PCD was initiated in the tapetal, chalice, and connective cells during tetrad stage after mitosis of the anther tissue cells; however, anther vascular tissues underwent PCD during microspore mother cell stage.

结果表明绒毡层、环形细胞、药隔组织细胞在减数分裂后四分体时期开始出现PCD，而花药维管束细胞从小孢子母细胞时期就开始出现PCD。

The result is consistent with previous studies. Whereas, tapetal cells of sterile anthers were disintegrated since tetrad cells were disjoined, indicating that disintegration of tapetal cells is earlier occurred in sterile anther than that in fertile anther. DNA ladder revealed that the cleavage of nuclear DNA into oligonucleosome-sized fragments to

结果表明，在花粉母细胞减数分裂后的四分体解离时期，不育花药的绒粘层细胞较可育花药提前开始裂解；在不育系S-Mo17rf3rf3花药和花粉S-(rf3)中均明显出现PCD过程的DNA片段化以及线粒体细胞色素C外渗的现象，证明了玉米CMS-S的花粉败育与花药绒粘层细胞的提前凋亡和小孢子细胞的细胞程序性死亡有关。

According to anther abortion characteristics and hormone functions, it was suggested that IAA, GA3 and ZR deficiency might be associated respectively with the inhibition of starch grain accumulation, pollen mother cell and tapetal cell expansion and tetrad formtion, and that abortion and even death of pollen mother cells and tapetal cells in sterile anther might be accelerated by high ABA accumulation.

根据内源激素的功能推测，不育花药IAA含量过低使花药淀粉积累受阻，GA_3含量不足影响花粉母细胞和绒毡层细胞的膨大，过低的ZR含量使花粉母细胞不能分裂形成四分体，过高的ABA含量促进花粉母细胞退化和死亡。

No tapetal cells were formed or tapetam collapsed at very early stage in some anther chamber during the microsporogenesis; Pollen mother cells in another chamber were not developed and microspore vacuolized; Tapetum cells developed abnormally, giantized and crammed the anther chamber; Some tapetum cells developed normally, but PMCs developed abnomally, which deformed at sporogeneous stage, and then were abhensive each other and finally degenerated. Nearly no PMCs could complete the process of meiosis, and form the tetrad, leading to the failure of normal microspore development.

药室的绒毡层细胞不形成或提前解体；药室内的花粉母细胞不发育或小孢子液泡化；绒毡层细胞发育异常，出现巨型化而挤满整个药室；绒毡层细胞虽发育正常，但花粉母细胞发育异常，在造孢细胞时期即开始出现变形现象，随后发生粘连退化；绝大部分花粉母细胞不能完成正常的减数分裂过程形成四分体，导致小孢子退化。

Pollen morphology of Vaccinium ashei was investigated by scanning electron microscopy. Most of pollen grains are tetrahedron with tetrad construction.

扫描电镜下，兔眼越桔花粉为四合体，外形为准四面体，中等大小，表面具不规则皱波状纹饰，并有多处凹陷。

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。

For a big chunk of credit-card losses; the number of filings (and thus charge-off rates) would be rising again, whether

年美国个人破产法的一个改动使得破产登记急速下降，而后引起了信用卡大规模的亏损。

Eph. 4:23 And that you be renewed in the spirit of your mind

弗四23 而在你们心思的灵里得以更新