[DNA content and sulfurous nuclear proteins of Ehrlich ascites tumor cells in relation to growth]

The proliferative behaviour of the Ehrlich ascites tumor in dependence on age after transplantation is characterized by pulse cytophotometrical DNA measurements as well as by determination of the sulfhydryl groups of the nuclear proteins. With increasing tumor age the DNA measurements show a decrease of the percentage of cells in S phase. During the first days of growth increases the percentage of cells in G1 phase. The percentage of cells in G2 and M phases increases strongly in the later days of growth. By the reaction of protein thiols with DDD and Fast Blue B cells with higher and lower concentration of SH groups of the nuclear proteins can be distinguished in two groups. By succeeding analysis of one and the same cell could be proved that the cells with higher SH concentration also possess a higher concentration of nuclear dry mass. On the basis of our own investigations and of data in the literature is suggested that the cells with higher nuclear SH concentration represent the visualized proliferating compartment of the tumor cell population.