Lysine-mediated tissue osmication in combination with a tannin-osmium conductive staining method for non-coated scanning electron microscopy of biological specimens.

Glutaraldehyde fixed rat kidney blocks showed no charging effect when treated with lysine and osmic acid and viewed in a scanning electron microscope using an acceleration voltage of 5-30 kV and a specimen current of 1 X 10(-10) A. The podocyte processes and endothelial micropores of the glomerulus were visible without metal coating. Glutaraldehyde fixed, tannin-osmium impregnated and lysine-osmium treated specimens also showed no charging effect in the scanning electron microscope, yielding instead much clearer scanning images which were comparable to those obtained from gold-coated specimens or from tannin-osmium-thiocarbohydrazide-osmium impregnated specimens (Murakami and Jones, 1980).