洋葱根尖细胞核在发育中的电镜观察

用透射电镜观察了洋葱根尖细胞核在发育过程中的变化。在正常细胞中,核一般为园形,位于细胞中央,并有一个大的核仁。随着细胞的衰老,染色质开始凝聚,常常通过细胞壁上的胞间连丝进入相邻细胞。在此过程中,有的核有核膜;有的虽有核模,但不清晰;有的核膜已经消失,完全成为一团电子密度很高的染色质。细胞核穿壁具有一定的规律性,它总是从衰老程度较轻的细胞穿向衰老程度较重的细胞。

ULTRASTRUCTURAL CHANGES OF NUCLEI DURING DEVELOPMENT OF ONION (A. CEPA L. ) ROOT TIP CELLS

Uitrastructural changes of nuclei during the development of onion (A. cepa L. ) root tip cells have been observed by TEM. In general, the nucleus in a normal cell is round, it locates in the centre of a cell and contains a larger nucleolus. With cell senescence, its chromatin agglutinates and passes to an adjacent cell through the plasmodesmata in the cell wall. During the process, some unclei possess nuclear membranes, some nuclei possess unclear nuclear membranes , some nuclei have no nuclear membranes at all, being a high electron - density material. The phenomenon of the nucleus passing the cell wall obeys a certain rule. It always passes to a more senescent cell from a less senescent cell.