SEDIMENTATION ANALYSIS OF TETRAPLOID FORMATION IN RAT HEPATOCYTES

抄録

Increase in tetraploid nuclei in relation to age was analyzed based on sedimentaion profiles of liver nuclei labeled with [³H]thymidine in vivo. On centrifugation, nuclei synthesizing DNA sedimented faster than theresting nuclei. Among the nuclei from rats of 3 weeks old, most of the labeled nuclei became diploid again, but in rats of 4 weeks old half of the labeled nuclei remained tetraploid. During week 5, the tetraploid nuclei were formed from diploid nuclei; these tetraploid nuclei did not show the ability to synthesize DNA yet. However, no further conversion of diploid to tetraploid cells occurred during week 6, whereas the percentage of cells with tetraploid nuclei was still increasing. Therefore, a definitive change in nuclear segregation after DNA replication seems to occur during weeks 4 and 5 after birth.