Electron-microscopical evidence that ribosomal chromatin of human circulating lymphocytes is devoid of histones

We have studied the distribution of histones in the nucleolus of human circulating lymphocytes in situ, using thin sections, either treated with antibodies against the core histones revealed by colloidal gold, or stained with the acrolein-silver methenamine technique for basic proteins. Gold particles were not found in the fibrillar centre, nor were silver-stained structures visible in this nucleolar component. Since the fibrillar centre contains the bulk of the ribosomal chromatin which is in a completely extended, non-nucleosomal configuration, our results indicate that this chromatin is devoid of histones.