Densitometric and chromatin texture parameters of hepatocyte nuclei during controlled autolysis

To determine the extent of the effect of autolytic changes in hepatocyte nuclei on the results of measurements of integrated optical density (IOD) of nuclei stained by the Feulgen method and its possible relationship with changes in chromatin texture.

Cytologic smears obtained from five pig livers by means of fine needle biopsy were fixed in 10% formalin at six time points after slaughtering (0-18 hours) and stained per Feulgen. In the hepatocyte nuclei IOD measurements were performed and supplemented with quantitative texture analysis. Texture analysis was carried out with our own algorithm, based on the movement of global gravity centers of heterochromatin granules during two-level, iteratively changed, grey thresholding.

The variability coefficients of IOD of diploid hepatocytes during autolysis increased from 0.061 (0 hours) to 0.363 (18 hours), and the ploidy histograms became aneuploid. The texture of chromatin became more homogeneous, but other features of the texture did not indicate a significant correlation with the duration of autolysis.

Autolysis is an important factor, which may influence the accuracy of DNA content and shape of ploidy diagrams. Changes in the morphologic pattern of heterochromatin may play a role in this, but the study was not conclusive because only one of six texture parameters (number of granules) changed parallel to mean IOD and autolysis time.