[DNA concentration and magnitude of cell nuclei in regenerating rat liver].

The DNA content in individual nuclei and the size of cell nuclei in the intact and regenerating liver 18 hours to 21 days after partial hepatectomy were studied in rats. In the intact rat liver most nuclei were found with a mean DNA content in the nucleus of 6 pg; as to the nuclear size--it was about equal to the size of the diploid nucleus (42.5 micronm2). In the regenerating liver DNA synthesis started before the 18th hour after partial hepatectomy. In most of the nuclei the DNA content by the 24th hour was found to be double that in intact animals, indicating a 85-90% engagement of hepatocytes by the first synthesis wave. After mitosis occurring in most cells before the 36th hour after partial hepatectomy much milder DNA synthesis waves followed at the 42nd and 60th hours.