Growth pattern of individual liver cells after partial hepatectomy in the rat.

The growth (i.e. changes in protein content) of isolated parenchymal cells of rat liver after partial hepatectomy has been investigated cytophotometrically. 3, 14 and 56 days after operation in rats of different age, no statistically significant differences could be measured in the Naphthol Yellow S-protein content of the most commonly found types of parenchymal cells in comparison with controls of the same age. An exaggeration of the hyperplasia of binuclear diploid (BD) and mononuclear tetraploid (MT) cells, characteristic for normal postnatal growth, could not be detected in any of the age groups investigated (30, 65 and 99 at operation). Consequently, it appears that the accelerated growth after partial hepatectomy mainly takes place by a growth mechanism primarily based on multiplication of cells (hypertrophy) as usually found in the embryonic period.