田旋花胚囊超微结构研究

Ultrastructure of mature embryo sac of Convolvulus arvensis

本工作对田旋花(convolvulus arvensis)胚囊受精前发育中的三个时期进行了超显微结构研究。结果表明,卵细胞、中央细胞和助细胞在受精前的一段时间内,超显微结构有很大变化。在所观察的发育阶段内,卵细胞核合成大量多聚核糖体,核糖体成团分布在细胞质中,周围大多环绕着内质网;中央细胞具传递细胞特征,在花期时,可观察到中央细胞侧壁、与助细胞相邻的壁上长有大量内突,这为中央细胞与助细胞之间存在物质交流、助细胞可从珠心组织获得代谢物质提供了结构证据;花苞期的中央细胞质内,高尔基体非常活跃,而到花期时高尔基体明显减少。助细胞具大量粗糙内质网,在发育中内质网形态与结构发生明显改变,从细长平行排列断裂成大量直径为3000(?)左右的囊泡群。充满助细胞质中,这说明。

The present paper deals with the ultrastructure of embryo sac in Convolvulus arvensis. The egg cell is high- ly polarized cell in which the mitochondria, dictyosome and endoplasmic reticulum are not active, where the ri- bosome is much produced and become aggregation from bud stage to anthesis. The ribosome aggregation is sur- rounded by rER usually. The large amount of ribosome in egg cell sugests that the egg cell has high rate and ca- pacity to synthesis protein. The central cell may be referred to as transfer cell. In anthesis there are many fingerlike projections on the lateral wall and the wall between the central cell and synergids, which suggests that the nutrition material can be transmited from nucellus cell into the synergids through the central cell. In bud stage the central cell contains large amount of dictyosome, some of them is near the egg cell, while the activity and number of the dictyosome are decreased obviousely in the anthesis. The structure and form of rough endoplasmic reticulum in synergids change from long and parallel into short and random with development, finally the rER break and become many vesicles and the synergids are filled up with the vesicles.