Using DGD embedment-free electron microscopy, ultrastructural observation on the intra- and intercellular microtrabecular network (MN) of the pollen mother cells (PMC) of the whole meiotic prophase Ⅰ in onion ( Allium cepa L.) was performed. Complex nuclear MN was observed in the nucleus of PMCs, spreading throughout the nuclear region. The nucleolus and chromosomes were connected with the MN filament network. The uniformity of nuclear MN changed with the development of the PMCs. A lamina-like structure surrounded the nucleus and joined the MN in nucleus and in cytoplasm, but it disassembled at the end of prophase Ⅰ. There was also a complex cytoplasmic MN in PMCs, without obvious variation during the prophase Ⅰ. Furthermore, MN in cytoplasmic connections (plasmodesmata and cytoplasmic channels) was noticed to link the frameworks in two neighboring PMCs into one entity. Cytomixis was observed at synizesis of prophase Ⅰ in this experiment, and MN in cytoplasm and in nucleus was noticed to distribute in these granules which migrated from one PMC into its neighboring cell. At this time the nucleus moved aside from center of the PMC, but the rest of the cell was still fulfilled with MN filaments. The relationships of nuclear MN with nucleolus and chromosomes, lamina with nucleus, as well as intra- and intercellular MN with cytomixis are discussed in this paper.
洋葱花粉母细胞细胞内、细胞间微梁骨架的
超微结构观察
杨军 余春红 王新宇 郑国锠*
（兰州大学细胞生物学研究所，兰州730000）
摘要：以洋葱(Alliumcepa L.)花粉母细胞为材料，采用DGD包埋去包埋原位技术，对花粉母细胞不同发育时期的细胞内、细胞间微梁骨架的超微结构进行了电镜观察。结果发现，花粉母细胞核内存在粗细不等的微梁骨架，与核仁和染色体紧密相连，随着发育的推移，其均一性发生改变。在核周有核纤层样的结构存在，与细胞核和胞质中的微梁骨架紧密相连，到前期结束时解体。洋葱花粉母细胞内具有发达的胞质微梁骨架，这种结构在减数分裂前期Ⅰ变化不明显。在胞间连接（胞间连丝和胞质通道）内，也有精细的微梁骨架分布，并且与两端细胞中的骨架相连。在凝线期的花粉母细胞中观察到细胞融合现象，有胞质或核内微梁骨架与穿壁转移的胞质小球和核小球内骨架相连。此时细胞核偏向一边，但细胞的其余部位仍充满了胞质微梁骨架。初步探讨了核微梁骨架与核仁和染色体之间的关系，核纤层与细胞核之间的关系，以及细胞内、细胞间微梁骨架与细胞融合之间的关系。
关键词： 微梁骨架；细胞融合；花粉母细胞；洋葱
全 文 ：