Polyploïdie somatique dans le foie de rat: I. Le rôle des cellules binucléées dans la genèse des cellules polyploïdes

Abstract

The formation of polyploid cells in the rat liver was studied in relation to the variation of the number of binuclear cells, directly determined by means of the method of liver cell suspensions. The polyploid cells appear in large numbers during the various types of growth of the hepatic tissue. Then, their appearance is strictly linked with the disappearance of a corresponding number of preexisting binuclear cells. This mechanism was verified in the course of the normal physiological growth and after partial hepatectomy, carried out on animals of various ages. It is impossible to induce the formation of polyploid cells in a liver which does not contain any binuclear cells (partial hepatectomy on animals less than 3 weeks old). These results clearly show that the binuclear phase is an intermediate stage between a given state of polyploidy and the immediately superior one. The binuclear cells give rise to two cells of higher ploidy owing to a particular kind of mitotic division. After a simultaneous prophase in both nuclei and the formation of only one spindle, the chromosomic groups fuse, giving a dipolar anaphase with a double chromosomic arrangement. Thus, the problem put by the hepatic polysomatism is mainly a question of determinism and mode of formation of binuclear cells.