甘薯珠心细胞衰退过程的超微结构研究

ULTRASTRUCDMAL STUDIES ON THE DEGENERATION PROCESSES IN SWEET POTATO NUCELLAR CELLS

阐述了甘薯珠心细胞衰退过程中的超微结构变化。发育成熟的珠心细胞，随着胚囊的发育和扩展以不同的方式衰退。在细胞质原位自溶方式，细胞质中的核糖核蛋白体密度迅速下降；细胞中可见许多被溶解的细胞组分的碎片；细胞核的染色质团块逐渐减少，核膜消失。最后在细胞中仅剩下细胞核和淀粉粒残体。在内质网对细胞质的吞噬和分隔方式中，同心环状和平行叠置的粗糙内质网大量增生，同时槽库膨大，并对细胞质组分进行分隔和吞噬；内质网膜膨大、断裂、分解，核糖体仍然存在，原生质体对电子染料的亲和性增强；接着质膜、液泡膜消失，原生质变为电子致密的物质。

The present paper reports the ultrastructural changes of the nucellar celis in sweet potato(Ipomeoa batatas)during tneir degeneration. The developed mature nucellar cells degenerate by way of difference during the development of the embryo sac. In the type of the autolysis of the cytoplasm in situ,the ribo-some density decreases dramastically in the cytoplasm of the nucellar cells.Debris of dissolved cytoplans-mic components distriouate throghout the nucellar cells. Chromatin masses in the nucleus decrease obvi-ously,Nuclear membrance disslolves. Finally,the remainder of the nucleus and starch grains can be seen in the nucellar cells.In the engulfment and sequestering of the cytoplasmic components by rough endoplasmic reticulum cisternae,the rough endoplasmic reticulum of concentric ring and parallel fold proliferates rapidiy,dilates,sequesteres and engulves the cytoplasmic components. The membrane of the rough endoplasmic reticulum dilates and dissolves,The ribosomes can still be seen. The cytoplasm is associated with increasing affinty of dyes,such as lead, Finally, cytoplasm converts to a dark disorga-nized mass.