ULTRAHISTOCHEMICAL STUDY ON RUTHENIUM RED SURFACE STAINING .2. NATURE AND AFFINITY OF ELECTRON DENSE MARKER

The electron-dense marker which is thought to produce the ruthenium red [RR] surface staining is studied. This stain is prepared under conditions which should give its rise in cell surface membrane; its nature and charge are tested electrophoretically and by measuring the turbidity, respectively. It is a positive colloid resulting from the recharging of colloidal OSO2 by RR polycations. Controls on the affinity are carried out by applying positive sol to gelled agarose sections containing hyaluronic acid, polyvinyl sulfate or polylysine. Controls are also carried out on [mouse] ascites Ehrlich carcinoma and [rat] Zajdela ascites hepatoma cells subjected to prior enzymatic and chemical treatments. The O-RR system visualizes all acidic groups in the outer hydrophilic leaflet, i.e., the greater part of compounds in this external cell layer. A model is presented for the mechanism underlying its rise in cell surface membrane.