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对沙打旺（Ａｓｔｒａｇａｌｕｓｈｕａｎｇｈｅｅｎｓｉｓ）的下胚轴、子叶、幼叶组织培养中脱分化细胞进行了超微结构观察，并着重讨论了细胞核的动态变化。脱分化细胞的细胞质中线粒体增加，嵴明显；多聚核糖体增多；高尔基体增加；质体中积累淀粉。核仁与核内异染色质之间有一个动态过程，此过程暂称“核仁物质喷射”~［１］现象。大致有以下步骤：１．核体（即核仁组织中心，ＮＯＲ）出现，半嵌在增大的核仁上，核内异染色质沿核膜凝聚；２．异染色质移向核仁，并与核仁接触，核体消失，部分异染色质进入核仁；３．核仁物质与进入核仁的异染色质混合后，以“珠带段” ~［１］的形式喷出。这一过程发生在有丝分裂的早前期，该现象可以看作是脱分化细胞的启动标志。
The ultrastructural observation of dedifferentiated cells in hypocotyl, cotyledon and young leaf tissue of Astragalus mutuensis was carried out. The dynamic changes of nucleus were also discussed. Decellularized cells increased in the cytoplasm of mitochondria, ridges obvious; polyribosomal increased; Golgi increased; accumulation of plastids in the plastid. There is a dynamic process between nucleolus and heterochromatin in the nucleus, this process is tentatively called “nucleolus injection” ~ [1] phenomenon. Roughly the following steps: 1. Nuclei (ie, nucleolar center, NOR) appear embedded in the enlarged nucleus, heterochromatin nuclear condensation along the nuclear membrane; Heterochromatin to the nucleolus, and contact with the nucleolus, nucleosomes disappear, some of the heterochromatin into the nucleolus; 3. Nucleolus substances and into the nucleolus after heterochromatin mixed with “beads section” ~ [1] the form of spray. This process occurs at an early stage of mitosis and can be considered as a hallmark of dedifferentiated cells.