[Polyploidization of mouse hepatocytes following repeated exposure to carbon tetrachloride]

A study was made of a change in the cell composition of the liver during regeneration induced by repeated (up to 8 times) administration of carbon tetrachloride with a one-month interval. The second administration entailed total polyploidization of hepatocytes. The subsequent stimulation of the regeneration process greatly enhanced polyploidization, with octoploid hepatocytes becoming the predominant cell type. The upper limit of polyploidization reached 64 n. The maximum mean ploidy amounted on the average to 11.1 n. for the nucleus and 12.5 n for the cell. These values were 2.8 and 2.2 higher, respectively, than the initial ploidy level. Proliferative potencies of polyploid hepatocytes and the mechanisms of retention of an exceedingly small number of diploid cells during intensive reparative liver growth are discussed.