对小麦旗叶衰老过程中的石蜡切片进行扫描电镜观察 ,结果表明 ,( 1 )旗叶衰老过程中 ,细胞核形态发生明显变化。即核呈球形 ,表面光滑 ,核孔匀称→核表面凸凹 ,部分核孔变大→核膜破裂 ,核解体 ,消失 ;( 2 )在籽粒成熟期小麦旗叶衰老及其细胞器退化消失明显加快 ;( 3 )细胞中叶绿体的退化、消失比线粒体稍快 ;( 4)叶肉细胞的细胞核比维管束韧皮组织细胞核解体消失稍快 The observation of the paraffin sections in the process of flag leaf senescence of wheat showed that: (1) The nuclear morphology of the flag leaves changed significantly during the aging process. (2) The flag leaf senescence of wheat and the disappearance of organelles disappeared evidently at the grain ripening stage; (2) (3) The degradation of chloroplasts in cells disappeared slightly faster than that of mitochondria; (4) the nuclei of mesophyll cells were slightly faster than the disappearance of the nucleus of vascular bundles