Electron microscopic toluidine blue staining of the erythrocyte membrane

Incubation in ferricyanide medium of toluidine blue stained erythrocytes produces opaque precipitates lining either aspect of the cell membrane. In addition, granular and needle-shaped precipitates occupy an intra- or extracellular position. Staining of the outer aspect of the membrane may reflect toluidine blue binding of the erythrocyte glycocalyx. Precipitates at the inner leaflet resemble Ca2+ affinity sites which were considered phosphorylated spectrins. Comparison with the light microscopic topo-optical toluidine blue reaction proved most of the electron dense precitates noncontributive to anisotropic staining.