【作者】 尹增芳；

【导师】 樊汝汶；

【作者基本信息】 南京林业大学 ， 植物学， 2000， 博士

【摘要】 利用光学显微镜和电子显微镜首次详细地观察研究了美洲黑杨维管形成层的发生和发育，结果表明： 1．美洲黑杨茎端由原形成层向维管形成层的转化是逐渐进行的，其细胞的超微结构特征呈现渐进式的变化，在叶发育成熟，节间伸长生长停止后，转化基本完成。 2．维管形成层为非叠生型，只具一层原始细胞，其细胞核分裂的过程与植物根尖和茎尖分生组织细胞基本相似，但胞质分裂方式非常特殊，新细胞板沿着细胞质柬的方向发育形成。 3．维管形成层木质部母细胞进一步分化形成导管、胶质纤维、韧型纤维和木薄壁细胞。木质部管状分子的分化分三个阶段进行：①细胞径向扩张；②具缘纹孔的发生和次生壁的构建；③原生质体的自溶。 4．维管形成层韧皮部母细胞分裂分化形成筛管、伴胞、韧皮薄壁细胞、韧皮纤维和少量的石细胞，筛管和伴胞来源于筛管母细胞的不均等有丝分裂。按照液泡膜和质膜的是否发生裂解可将筛管的发育划分为三个时期：①未成熟期；②成熟期；③衰退期。伴胞在筛管的衰退期表现出典型的细胞编程性死亡的细胞学特征。 5．维管形成层的活动具有明显的周期性。南京地区生长的美洲黑杨维管形成层一般在每年的3月中旬开始恢复活动，4月中旬至7月下旬为活动旺盛期，随后维管形成层的活动减弱，8月底到12月初为由活动向休眠转化时期，12月到翌年的2月为维管形成层的休眠期。在维管形成层细胞周期性活动中，细胞器及细胞内含物发生了一系列的动态变化。更多还原

【Abstract】 The initiation and development of Populus deltoides was studied first by using optical microscope and electron microscope in detail. The results were:1. The transition from procambium to cambium was a gradual process in the stem tip, and the ultrastructural feature changed by degrees. When internode elongation nearly was stoped, and the development of leaf was matured, the transition has almost completed.2.The vascular cambium was non-stratified. It has only one initial cell layer. The fine structure and sequence of events of mitosis in the dividing cambial cells apparently were similar to those of dividing cells in root and stem tips. Of special interest was the observation that during cytokinesis, a broad cytoplasmic plate preceded along the bundle of cytoplasm.3. The secondany xylem mother cell of vascular cambium were differentiated into vessels,gelatinous fibre,libriform fibre, and parenchyma cell. The differetiation process of tracheary elements was divided into three phases: ①The radial expanding of cell; ②The forming of pit bordered and secondary cell wall; ③The lysising of protoplasm.4. The secondary phloem mother cell were divided and differentiated into sieve tube,companion cell,libriform fibre, parenchyma cell,and a few sclereid cells,The sieve tube and companion cell was originated from inequality mitosis of sieve mother cell. The process of development of sieve tube was divided into three stages according to the lysising of tonoplast and plasmic membrane:①Immature stage; ②Mature stage;③The stage of decline. It appears to companion cell that the cellular feature was typical programmed cell death in the stage of decline of sieve tube.更多还原