Phosphorus compounds in animal tissues; the distribution of nucleic acids and other phosphorus-containing compounds in normal and malignant tissues.

Malignant tissues are distinguished from other types of tissues by their capacity for relatively unlimited and uncontrolled growth in the organism. The reason why neoplastic tissues grow continually, in contrast to embryonic tissues which grow only up to a certain point before they begin to differentiate, is a fundamental problem of cancer research. A study of the synthetic mechanisms of the cell is a logical approach to this problem. In this connection the nucleic acids have a special significance since the measurement of these compounds by means of ultraviolet spectrophotometry has demonstrated fluctuations in the nucleic acid content of the nucleus during the mitotic cycle and high concentrations of nucleic acid in the cytoplasm of cells which are actively dividing or which are engaged in protein synthesis (2-6). Although the spectrophotometric method is extremely sensitive and permits the measurement of the nucleic acids in small portions of single cells, the results of such measurements are open to criticism on the ground that the method is not sufficiently specific. The results obtained by the physical method can, however, be tested experimentally by less sensitive but more specific chemical methods. Recently a method for the extraction of the nucleic acids from animal tissues and their estimation by colorimetric reactions was described (13) and the nucleic acid contents of homologous normal and cancer tissues were determined (14). It was found that the cancer tissues contained much higher concentrations of nucleic acids than did the normal tissues. In the present report, the results have been extended to include a larger number of normal and malignant tissues.