Use of cis-Pt(II)-uracil for electron microscopic cytochemistry of rat brain nucleic acids.

Cis-Pt(II)-uracil staining reveals nucleic acids in a relatively specific manner when applied alone for 1 h to rat brain tissue specimens. Poor contrast and resolution are observed when glutaraldehyde-fixed and epoxyembedded thin sections are post-stained with cis-Pt(II)-uracil alone. Counterstaining thin sections with uranyl acetate decreases staining specificity by revealing many tissue proteins. Synapses did not stain, which suggests that they do not contain significant amounts of large RNA molecules. Technical procedures must be carefully regulated to avoid artifactual staining of cellular components other than nucleic acids.