Critical cytoplasmic mass and the initiation of the proliferative response in the rat liver.

DNA synthesis and cell division were observed in atrophied liver cells following partial hepatectomy. The atrophied cells passed through the mitotic cycle including the DNA synthesis phase without increasing their volume above that of normal non-dividing hepatocytes. The achievement of a critical cell mass does not appear to be the stimulus for DNA synthesis and cell division in the proliferative response which follows partial hepatectomy.