Heteropyknosis of the chromosomes in liver cells of different ploidy: a nuclear image study

The chromatin densities of Feulgen-stained diploid, tetraploid, octoploid and binucleate cells of smear preparations of the liver of female field voles, Microtus agrestis, were examined by means of image analysis. The ratio of the areas of flattened nuclei of 2n, 4n and 8n ploidy was about 1 : 1.62 :2.60 and that of the relative DNA content 1 : 2 : 4. In flattened polyploid nuclei, the chromosomes are more densely arranged than in diploid. In diploid nuclei, absolutely and percentually smaller areas of dark chromatin particles were found than in polyploid nuclei. After correction of the grey values with a density factor, the frequency distribution curves of all ploidy classes were found to be nearly identical. The results show that the percentage of heteropyknotic chromosome material is the same in diploid, polyploid and binucleate liver cells.