Distribution of nuclear size and DNA content in serial liver biopsies of rats treated with N-nitrosomorpholine, phenobarbital and butylated hydroxytoluene.

Nuclear size distribution and DNA content distribution were determined in liver biopsies of rats using an electronic particle counter and an impulse cytophotometer, respectively. Nuclear size distribution and DNA content distribution were found to be highly correlated regardless whether peak areas or peak heights of the histograms were compared. Treatment with the hepatocarcinogen NNM caused a dose-dependent increase in octoploid nuclei and a shift of the 2 n : 4 n ratio in favor of the diploid nuclei. Treatment with Pb and BHT had minor effects on nuclear size and DNA content distribution. The paper demonstrates the usefulness of the fine-needle aspiration biopsy procedure for the evaluation of liver changes induced by chemical substances.