Prospects for microscopical cytochemistry.

This review is devoted mainly to an evaluation of the status of microscopical cytochemistry seen as a discipline aiming at both the localization and the quantification of molecular processes in cells. Its relationships to ultramicrochemistry, as well as, in a broader sense, to biochemistry and cell biology, are discussed from both the historical and the methodological points of view. Recent developments in quantitative cytophysical techniques, such as automated cytophotometry using microscopes fitted with flying spot systems, TV cameras, or scanning stages, and the development of rapid flow cytometers are discussed. Analytical electron microscopy is touched upon too. The main part of the review is devoted to recent trends that strengthen the analytical basis of cytochemical staining methods. The special character of staining procedures as a kind of matrix chemistry is discussed and the potentialities of the use of matrix-incorporated compounds for the fundamental study and calibration of microscopical staining procedures are elaborated. Parallel developments in the theory and practice of matrix chemistry in biochemistry are stressed. Growing interrelations between microscopical cytochemistry and related fields of investigation, such as the controlled fragmentation of cells, and methods like ultramicroanalysis of individual cells are indicated.