【摘要】 本文报告了关于（矮丰2号×卡捷姆）F₁小麦小孢子母细胞和减数分裂的三维结构的光学显微镜分析。小孢子母细胞是一个厚铁饼状细胞,横截面为园形,直径25—27微米;而纵截面为一椭园,其长轴与直径相等,短轴约15微米。正常小孢子母细胞中期Ⅰ和Ⅱ的染色体排列表明,分裂纺锤体轴是平行于横截面的,在这个平面内,两次分裂的纺锤体轴互相垂直并通过陆续形成细胞壁,产生二轴对称型的四分孢子。在一些小孢子母细胞中（约8—18%）染色体行为不正常,此外,中期赤道板的数目和方向也有一些变化,在极端情况下,纺锤体轴的方向转动90°,变成垂直于园形平面,胞质分裂不能完成,因而不能形成非二轴对称的四分孢子。在四分孢子期,发现有一些多细胞结构,其形态与花药培养中的花粉胚很相似。但这些多细胞结构来源于小孢子母细胞,并且在以后的阶段迅速即消失;所以,它们可能与花粉胚是不同的和无关的。F₁的减数分裂中的这些不正常现象说明,它的亲本中包含有远缘的遗传成分,这可能是这个材料花粉胚诱导频率很高的内在因素。更多还原

【Abstract】 In this article we presented a light microscopic analysis of threedimentional structures of microsporocyte during meiosis of wheat plants （Aifeng NO 2x Cajeme） F 1.From the beginning of meiosis to its end, the microsporocyte is a thick discus-like body. The transverse section of the body is a round plane with a diameter about 25-27 micron, but the vertical section is an oval which has a short axis being a little more than a half of long one and the latter is equal to the diameter. In the most of microsporocytes, meiosis is normally proceeding; the arrangement of chromosomes in metaphases 1 and 11 of meiosis shows that the axes of dividing spindles are parallel to the transverse round plane and in this plane the spindles’ axes of two divitions are perpendicular to each other, then through two succesive plasmodieresis the isobilateral tetrad is generated. In some of microsporocytes the abnormalities of chromosomes behavior and the changes in numbers and orientation of equatorial plates are observed. In a few cases, in one half of a dyad all the chromosomes lie separatelly in the round plane, which means the orientation of spindle’s axis had turned a right angle and perpendicular to the plane. The changes in spindle’s orientation should need to form a wall of larger area than normal. In the last cases plasmodieresis would fail to complete because the area of new wall is too much larger than the minimum one required according to the Errera’s principle, thus non-isobilateriar tetrad could not be produced. In the stage of tetrad there are some multicellular structures which resemble to the pollen embryoids in anther culture. These structures, however, are initiated from microsporocytes but not microspores and quickly disappeared in folio-wing stages, they should not be identical or relative to the pollen embryoids. At last, the abnormalities of chromosome behavior we observed are very similar to those in the offsprings of hydridization between wheat and other related species, though the frequency of abnormalities is much lower than that in the latters. So it was supposed that in the F₁ plants there might be heterogenetic components stemed from the parents. and these would be the internal factors effecting on the formation of abnormal pollen grains in vivo and production of pollen embryoids in vitro.更多还原