Comparative microphotometric determinations of deoxyribonucleic acid in normal and tumorous growth of fern prothalli.

Abstract

DNA in individual nuclei of normal and tumorous growth of fern prothalli in vitro has been determined by photometric measurements of the Feulgen reaction. The normal prothalli show DNA amounts in the 1 C to 2 C range, as do certain nontumorous aberrant growth forms. Newly isolated tumor strains are essentially like the normal prothalli in DNA pattern, but in subsequent passages in culture they develop a spectrum of DNA values from the normal to much higher levels. This shows that polyploidy is neither causal to, nor even present in, the initiation of this type of tumorous growth, but that it is clearly a secondarily acquired and perhaps diagnostic characteristic. The persistence of some cells in the normal range and the heterogeneity of the cell population comprising the tumor are considered significant factors in the interpretation of varied behavior and apparent “recovery” from the tumorous condition.