[Current state of the problem of electron-cytochemical detection of DNA]

Direct and indirect methods for electron microscopic detection of DNA are reviewed. Indirect methods based on DNA removal or preferential contrasting of RNP-structures make it possible to define DNA localization only in outline. By means of direct methods it is possible to reveal all three components of DNA-phosphoricacid groups, pseudoaldehyde groups of desoxyribose, nitrogen bases. Within the framework of this classification the reactions suggested so far and the results obtained with them have been discussed. The main difficulty--lack of specificity, low contrast, poor reproduction, damage of ultrastructures.