Uranyl acetate solution has widely been used as staining reagent for samples processed for ultrastructural morphology, cytochemistry, and immunocytochemistry. Although uranyl acetate guarantees high performance as a staining reagent, the radioactive uranyl salts make its use and purchase severely restricted. In this view, we used a non-radioactive lanthanide mix solution as contrasting dye for both nucleoplasmic and nucleolar ribonucleoprotein-containing components. This method guarantees a good contrast without masking the probe-antigen immunoreaction, thus proving to be a suitable tool for high-resolution studies of both cyto- and immunocytochemistry on acrylic resin-embedded samples.