Improvement of the method for demonstration of nucleolar organizer regions (NORs) in formalin fixed and paraffin embedded tissue using microwave pretreatment.

For demonstration, accurate evaluation and measurements of nucleolar organizer regions (NORs) in nuclei, a good quality reaction of silver staining is required. On formalin fixed and paraffin embedded tissue this can be achieved only, if special procedures are used. We managed to get sharply delineated, dark brown or black dots representing AgNORs (silver stained NORs), that are easy to count and measure, with microwave pretreatment of tissue sections before incubation in silver solution.