Analytical SEM of cell polyanions stained with tris(2,2'-bipyridine)ruthenium(II).

Peritoneal mast cells and lymphocytes from mice were placed on graphite supports, fixed in methanol, stained with the new fluorochrome tris(2,2'-bipyridine)ruthenium(II) and microanalysed using scanning electron microscopy (SEM). X-ray microanalysis showed the expected signal of P and S (K alpha lines) in emission spectra of lymphocytes and mast cells. The signal of Ru (L alpha 1 and L beta 1) overlapped with that of Cl, although the peak in the corresponding region was about 7 times higher than that from unstained cells. X-ray images showed the topographic localization of P, S and Ru in mast cells and lymphocytes and confirmed the accumulation of the Ru complex in heparin- and DNA-containing structures. These results indicate that, by using suitable marker elements and detection methods, analytical SEM is a useful complement in cytochemical studies.