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(A) Conventional electron microscopic sample preparation. (B,D) The DNA fibers appear in the nucleolar region after NAMAUr DNAspecific staining, (C) the lowest electronic density region contains DNA clumps. Immunolocalization of fibrillarin and specific DNA staining in nucleoli of Allium sativum cells. The gold particles are restricted to nucleoli. Gold particles are mainly distributed over the DNA fibers. In situ hybridization using an rDNA probe on sections processed with specific DNA staining. Gold particles are distributed over the DNA fibers. The configuration of rDNA in the nucleolus after DNAspecific staining. The rDNA fibers are distributed around the FC, forming multiple cir