Ultrahistochemical study on the ruthenium red surface staining. I. Processes which give rise to electron-dense marker

The cell coat picture effect which is usually obtained with the conventional RR method, that is with the RR/OsO4 coupled reaction, is investigated. In this first paper, each of conceivable events which might take place between RR, OSO4 and cell surface membrane is discussed or studied. Various tests are carried out on ascites Ehrlich carcinoma cells and Zajdela ascites hepatoma cells treated with numerous chemical reagents, as also on a few pure proteins. The set of data supports the concept that the staining pattern is due to the combination in surface membranes of RR with a "colloidal-like" form of OsO2. The latter might occur during the formation of stable cyclic osmic acid diesters between OsO4 and membrane unsaturated lipids. A possibility by which the resulting marker is though also to be in a "colloidal-like" state is put forward. A next report will deal with this problem.