Cytophotometric studies of the DNA, nucleic acid and protein content of human liver cell nuclei.

Cytophotometry was performed on human liver cell nuclei obtained from liver biopsies in 18 patients with normal or practically normal liver histology as judged by light microscopy. Imprints of liver cells and liver cells or liver cell nuclei obtained by different isolation procedures were studied. The nuclear DNA, total nucleic acid and protein content was evaluated after Feulgen, gallocyanin and naphtol-yellow staining and by UV-spectrophotometry. The nuclear area was obtained during the cytophotometric scanning procedure (Zeiss UMSP I). A total of 2,330 nuclei were investigated and approximately 80 per cent of these were diploid. The diploid value was confirmed by UV-spectrophotometry where a total nucleic acid content of approximately 7 pg was found. The nuclei could be grouped in classes corresponding to di-, tetra- and octaploid nuclei, according to their contents of DNA, total nucleic acid and protein and according to their size. The variation in nuclear contents was lowest for DNA with a coefficient of variation of approximately five percent, and highest for the protein content (15 per cent). Within diploid nuclei, insignificant as well as significant correlations between DNA content and size were found, but taken all together a weak positive correlation is likely. Higher correlations were found between nuclear nucleic acid content and size and between nuclear protein content and nuclear size.