[Ultrastructure of human cancer cells during mitosis]

200 mitotic cancer cells from 35 varieties of human malignant tumor were studied by electron microscope. The results showed that: 1. Besides the a typical mitotic figures observed under light microscope, there was no significant difference in ultrastructure during the mitotic phase between cancer cell and non-cancer cell; 2. Judging by the ultrastructure of the tumor cell, about 90% of mitotic tumor cells seemed to be undifferentiated, there was no unique characteristic by which a cell differentiation could be made. Only 10% of the mitotic tumor cells belonged to poorly differentiated cells with the cell origin identified. None of the mitotic figures was found in well-differentiated tumor cells. Pathologically, it was reasonable to classify the tumor according to the degree of cell differentiation; 3. During mitosis, the nucleoli disappeared completely or presented themselves in small pieces scattered in the vicinity of the chromosome. No euchromatin was seen and most of polyribosomes were depolymerized into monoribosomes. The ultrastructure seemed to indicate that protein synthesis was inhibited in the mitotic cycle; and 4. In about one half of the mitotic tumor cells, paired cisternae (or confronting cisternae) were found in the cytoplasm, while paired cisterna was observed in a few cells among the thousand tumor cells in the interphase, so paired cisterna was obviously related to the mitotic cycle.