"Non-condensed" and "condensed" chromain in transitional cell carcinoma of the human urinary bladder.

The area and content of "non-condensed" and "condensed" chromatin in smeared Feulgen-stained malignant urothelial cells were determined by means of scanning-cytophotometry. The results were compared with those from similar measurements of benign human transitional epithelial cells. There was no difference between the relative area and content of "non-condensed" and "condensed" chromatin in cancer nuclei and normal urothelial nuclei as far as nuclei of the same size and ploidy class were considered. Within the same ploidy class the relative area and content of "non-condensed" chromatin increased with increasing nuclear size. As increased nuclear size within the same ploidy class is typical for most cancer cells, cancer specimens therefore contained relatively more "non-condensed" chromatin than normal urothelium. Analogously the relative values of "condensed" chromatin decreased in cancer specimens. Only in high-polyploid cancer cells, which occurred more frequently in undifferentiated tumours, a slight decrease of the relative area and content of "non-condensed" chromatin was observed as compared with well differentiated diploid tumour cells. It was in polyploid tumours that the absolute area and content of "condensed" chromatin was increased as compared with diploid normal urothelium. This means that the changes in "non-condensed" and "condensed" chromatin were primarily dependent on nuclear size and total chromatin content and were not found to be a characteristic of cancer nuclei as compared with control nuclei of the same size and ploidy. These findings differ from the results of biochemical analyses of heterochromatin both in cells during carcinogenesis and also in cancer cells, but are in agreement with qualitative and quantitative morphological studies of smeared cancer nuclei.