Behavior of tumor cells with lobated nuclei in the MTK-IV tumor after some treatments

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With the purpose to explore the mechanism of the formation of lobated nuclei in the MTK-IV tumor, the daily frequencies in occurrence of tumor cells with lobated nuclei were experimentally studied in three clones derived from the original stock. The MTK-IV tumor is characterized by the occurrence of cells with lobated nuclei in 10 to 30 percent of frequency (Tonomura 1956).This study involves the following three experiments: (1) intraperitoneal inoculation with isolated nine tumor cells; (2) intraperitoneal inoculation with an isolated single tumor cell; and (3) intraperitoneal injection with the chemical (podophyllotoxin) after transplantation of the tumor. The single and nine-cell inoculations were made following the technique devised by Makino and Kano (1955) for the Hirosaki sarcoma. Podophyllotoxin used here is known as a powerful mitotic poison. The observations were carried out by means of the smear method with acetic dahlia.(1) Nine-cells clone (Fig. 3): A rat received nine isolated tumor cells developed a tumor in its peritoneal cavity. In the tumor samples taken on the 24th day after inoculation, the frequency in occurrence of tumor cells with lobated nuclei showed 76 percent. The tumor was transmitted by peritoneal injections for forty-three generations. The frequencies of cells with lobated nuclei increased during early transfer generations (Table 1-A). In the 43rd generation the daily frequencies of cells with lobated nuclei were 7 to 19 percent, being nearly identical with those of the original stock tumor.(2) Single-cell clone: In the ascites tumor which was developed through the introduction of a single tumor cell the daily frequencies in occurrence of tumor cells with lobated nuclei were observed. The frequency of tumor cells with lobated nuclei observed in the 1st generation is about 2 times higher than that of the original stock tumor. It gradually decreased towards the later generations. A percentage value identical with that of the original stock tumor was obtained in the observation of the 20th generation (Table 1-B).(3) Chemically treated clone: From the above results it is deduced that the formation of nuclear lobes in tumor cells is to be connected with an unfavorable environmental condition of the tumor. The following experiment was undertaken to ascertain the above assumption. Intraperitoneal injection With podophyllotoxin was made in tumor-bearing rats on the 2nd day after transplantation, and the change in frequency of tumor cells with lobated nuclei was studied (Fig. 6). The frequency observed prior to experiment was 12 percent. The highest percentage (32%) in frequency was obtained in the sample 12 hours after treatment. The tumor was transmitted for seven generations. In the 7th transplant generation, the daily frequencies of tumor cells with lobated nuclei were 9 to 13 percent, showing an approximately equal value to that of the original stock tumor.From the results obtained in the above experiments, the conclusion may be possible that the formation of nuclear lobes in tumor cells of the MTK-IV tumor seems to be closely associated with an unfavorable environmental condition of the tumor, or that nuclear lobes are to be formed when the tumor cells are exposed to an unsuitable condition.
日本遺伝学会の論文

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久田洋子
北海道大学理学部動物学教室

Behavior of tumor cells with lobated nuclei in the MTK-IV tumor after some treatments

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