Improved silver staining of nucleolar organiser regions in paraffin wax sections using an inverted incubation technique [published erratum appears in J Clin Pathol 1991 Jun;44(6):528] A new simple modification to the silver staining of nucleolar organiser regions (AgNORs) was devised which, by performing the incubation with the slide inverted, results in minimal undesirable background staining, a persistent problem. Inverted incubation is facilitated by the use of a commercially available plastic coverplate. This technique has several additional advantages over other published staining protocols. In particular, the method is straightforward, fast, and maintains a high degree of contrast between the background and the AgNORs. 