[Value of silver staining technics for the analysis of nucleolar organizer regions and their morphological and functional variations].

Different aspects of nucleolus organizing materiel are found in acrocentric "variants", after specific Ag-staining. These various aspects being linked to the transcriptional activity of rRNA genes, the variant D and G chromosomes do not constitute a homogeneous group. Ag-staining shows also different types of satellite associations, some of them seems more dissociable than others.