大葱小孢子母细胞至二胞早期花粉发育的超微结构观察

用电镜观察了章丘大葱 (AlliumfistulosumL .)从小孢子母细胞至二胞早期花粉发育的超微结构。终变期的花粉母细胞 ,胼胝壁外方的相邻初生壁间及胞间隙内 ,存在胞间物质 ,四分体期 ,此物质尚部分存在。小孢子母细胞减数分裂前 ,细胞质内含有脂滴 ,小孢子有丝分裂以后 ,脂滴增多增大。小孢子分裂后期 ,质体已积累淀粉粒 1至多个。二胞早期花粉之营养细胞质内 ,有些含淀粉质体亦含脂滴。各发育期 ,核糖体及多聚合糖体丰富 ,并有很多的粗面内质网、高尔基体及小泡、线粒体 ,显示蛋白质、糖类及其它物质合成及运输作用的活跃。小孢子缺中央大液泡。有丝分裂后期 ,细胞器集中于未来的营养细胞极。小孢子胞质分裂期 ,有些内质网贴近或与花粉质膜相连 ,它们或有可能互相融合 ,扩大质膜面积而适应花粉的生长。还讨论了不同时期高尔基体小泡的作用。

Observations on Ultrastructure of Pollen Development from Microsporocyte to Early Two-Celled Pollen in Welsh Onion (Allium fistulosum)

The ultrastructure of pollen development from microsporocyte to early 2-celled pollen in Welsh onion cv. Zhangqui was studied by using transmission electron microscopy. At diakinesis intercellular substance exists between the primary walls outside the callose walls and within the intercellular spaces of the microsporocytes. This substance still partly remains at tetrad stage. Before meiosis the microsporocytes have lipids in cytoplasm. After microspore mitosis the lipids increase in both number and size. In anaphase the plastids in the microspore cytoplasm accumulated one to several starch grains. In early 2-celled pollen, some starch-containing plastids in vegetative cytoplasm also contain lipids. At all developmental stages, free and polyribosomes are abundant, and a large amount of rough endoplasmic reticulum(RER), dictyosomes and vesicles and numerous mitochondria are present. These features indicate that sythesis and transportation of proteins, saccharides and other substances are active. The microspore lacks a large central vacuole. At anaphase of mitosis, the organelles in microspore cytoplasm are concentrated in the future vegetative cell pole. Microspore at cytokinesis, some RER are close to or associated with the pollen plasma membrane They may fuse with each other and enlarge the plasma membrane surface to adapt the growth of pollen grain. The functions of dictyosome vesicles at various stages of development are discussed.