Cytological Events during Zygote Formation of the Fern Ceratopteris thalictroides  

作　　者：Jian-Guo Cao Quan-Xi Wang Nai-Ying Yang Wen-Mei Bao 

机构地区：[1]College of Life and Environment Science, Shanghai Normal University, Shanghai 200234, China

出　　处：《Journal of Integrative Plant Biology》2010年第3期254-264,共11页植物学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China (30670128);Leading Academic Discipline Project of Shanghai Municipal EducationCommission (J50401);Project of Shanghai Municipal Edu-cation Commission (08YZ67)

摘　　要：The cytological events, including nuclear fusion, digestion of male organelles and rebuilding of the plasmalemma and cell wall, during zygote formation of the fern Ceratopteris thalictroides （L.） Brongn. are described based on the observations of transmission electron microscopy. When the spermatozoid enters the egg and contacts the cytoplasm, the male chromatin relaxes continually. The microtubular ribbon （MTr） is separated from the male nucleus and then an envelope reappears around the male nucleus. During nuclear fusion, the egg nucleus becomes highly irregular and extends some nuclear protrusions. It is proposed that the protrusions fuse with the male nucleus actively. After nuclear fusion the irregular zygotic nucleus contracts gradually. It becomes spherical before the zygote divides. The male chromatin is identifiable as fibrous structure in the zygotic nucleus in the beginning, but it gradually becomes diffused completely. The male organelles, including the MTr, multilayered structure, flagella and the male mitochondria are finally digested in the zygotic cytoplasm. Finally a new plasmalemma and cell wall are formed outside the protoplast. The organelles in the zygote are rearranged, which produces a horizontal polarity zygote. The zygote divides with an oblique-vertical cell plate facing the apical notch of the gametophyte.The cytological events, including nuclear fusion, digestion of male organelles and rebuilding of the plasmalemma and cell wall, during zygote formation of the fern Ceratopteris thalictroides （L.） Brongn. are described based on the observations of transmission electron microscopy. When the spermatozoid enters the egg and contacts the cytoplasm, the male chromatin relaxes continually. The microtubular ribbon （MTr） is separated from the male nucleus and then an envelope reappears around the male nucleus. During nuclear fusion, the egg nucleus becomes highly irregular and extends some nuclear protrusions. It is proposed that the protrusions fuse with the male nucleus actively. After nuclear fusion the irregular zygotic nucleus contracts gradually. It becomes spherical before the zygote divides. The male chromatin is identifiable as fibrous structure in the zygotic nucleus in the beginning, but it gradually becomes diffused completely. The male organelles, including the MTr, multilayered structure, flagella and the male mitochondria are finally digested in the zygotic cytoplasm. Finally a new plasmalemma and cell wall are formed outside the protoplast. The organelles in the zygote are rearranged, which produces a horizontal polarity zygote. The zygote divides with an oblique-vertical cell plate facing the apical notch of the gametophyte.

分 类 号：Q949.36[生物学—植物学] Q2