黑节草雄配子体形成的超微结构研究

四分体内各小孢子之间具有发达的胞质通道可见各种细胞器穿过此通道,初期的生殖细胞和营养细胞的细胞质中的细胞器没有明显差异,但在以后发育中,生殖细胞和营养细胞表现出明显的异质性,生殖细胞中始终未发现质体,其它细胞器不仅数量少,而且体积小,结构简单。与此相反,营养细胞内各种细胞器明显增多,而且体积大,结构发达,质体内可见有淀粉的沉积,特别值得指出的是,在营养细胞中发现一种结构较特殊的质体,这一现象在其它植物中尚未见报道过。

Ultrastructural Studies of the Formation of Male Gametophyte in Dendrobium Candidum Wall E x Lindl

The present paper dealed with the formation of male gametophyte in Dendrobium candidumWall. ex Lindl. at the infrastructure level.There were the cytoplasmic channels between the microspores, the movement of various organells from one microspore to the neighbouring microspores through the channels can been seen. The phragmoplast formed in telophase of the first microsporic mitosis extended centrifugally until it connected with the wall of the pollen grain. A new cell wall was then formed to separate the generative and vegerative cell. By unegual cytokinesis the former was small and the latter large. In early developmental stage of the male gametophyte, the organells in cytoplasm of the vegetative cell and generative cell were similar, including mitochondria, dictyosomes, reticulum and ribosomes.In the further developmental stage of the male gametophyte, the heterogeneity between the vegetative cell and the generative cell was then very conspiceous. The organelles in the cytoplasm of generative cell were obviously fewer, smaller and their structures were simpler than those in the vegetative cytoplasm . The deposition of starch in the plastids of the cytoplasm of the vegetative cell was found.Acase particularly worthy to report was a new plastid with special structure was found in the vegetative cytoplasm. This case had been not yet reported.