Feulgen reaction and quantitative cytochemistry of desoxypentose nucleic acid. I. Estimation of the loss of tissue DNA caused by fixation and acid hydrolysis

Nucleic acids are retained quantitatively in rat tissues fixed with formalin or alcohol-formalin. Appreciable fractions of desoxypentose nucleic acid (DNA) are liberated from non-fixed as well as fixed tissues during the course of Feulgen hydrolysis for 13 minutes. The loss of DNA is decreased decidedly by the preliminary fixation, 8% on average, showing an irregular fluctuation which seems to be independent of the fixatives or tissues employed.The results of different investigators are discussed, and the validity of the Feulgen reaction as a quantitative-cytochemical test of DNA is examined under the light of the conclusion reached finally.