Heterogeneity of silver staining in the marker chromosome of rhesus monkey ( Macaca mulatta)

Nucleolus organizers were stained by the Ag-As silver method in Macaca mulatta. The marker chromosomes which carry the sites for rDNA synthesis were stained positively by this technique. These chromosomes showed a wide range of variability with respect to staining behaviour. Some of the marker chromosomes carried silver stain bilaterally whereas in others they were located unilaterally. It seems likely that the total number of rDNA gene varies among different animals and in each case the marker chromosomes are stained by the Ag-As method to a different extent.