Selection of optimum tetrazolium salts for use in histochemistry: the value of structure-staining correlations.

A structure-staining correlation study was made of a number of tetrazolium salts and formazans used in histochemistry. Numerical parameters describing molecular structure were calculated from structural formulae. Staining data were from previously published work. It was found that several significant practical variables (namely, uptake and reducibility of tetrazolium salts; substantivity, lipid solubility, and crystal size of formazans) could be predicted from structural parameters. Possible applications of these correlations are discussed: to increase our understanding of existing staining systems and to guide the design and selection of new tetrazolium salts for histochemical use.