棉花花粉不同发育时期的扫描电镜观察

用石蜡切片扫描电镜观察技术，研究陆地棉品种鄂荆１号花粉不同发育时期的超微结构。观察到成熟花粉母细胞胼胝质壁的一段断裂成２～３节，断面光滑整齐。花粉壁的形成是从四分孢子期中的小孢子开始产生原外壁。单核花粉早期（核在中央）细胞壁加厚，内、外壁已形成，其上有少量细小的刺状突起。单核靠边期花粉壁的形成过程全部完成，壁上已有密集的发育完好的刺状突起和萌发孔，棉花花粉壁形成所需时间较有些被子植物短。在单核早期

OBSERVATION BY SEM OF COTTON POLLENS AT DIFFERENT DEVELOPMENT STAGES

Dissected with paraffin,the ultrastructure of upland cotton pollens was investigated at different development stages using a scanning electron microscope.It is shown that there was a part of the callous wall broken into 2 to 3 pieces in the mature pollen mother cells,with a smooth breaking section.The formation of the pollen walls began with the production of primexine at the tetrad stage.The cell wall was thickened at the early uninuclear stage(the nucleus is located in the pollen center),when the endospore and epispore were formed and some sparse and fine spinescent protuberance were seen on the pollen wall.The pollen walls were formed completely at the stage with uninucleus adjacent to the pollen wall,with conglomerate and fully developed spinescent protuberance and tremata on the wall.The time neesed for the formation of pollen wall is seemingly shorter in cotton than in some other angiosperm.Furthermore,a pore-like protrusion structure on the nucleolus was observed in the pollen at the early uninuclear stage.