Transcribed and nontranscribed parts of the human ribosomal gene repeat show a similar pattern of distribution in nucleoli.

The distribution pattern of the transcribed and nontranscribed parts of human ribosomal RNA genes were visualized simultaneously in the same cells by nonautoradiographic in situ hybridization. DNA probes labeled with either digoxigenin or biotin were detected in the same cells by different fluorescence systems. The signals from both the transcribed and nontranscribed parts showed a similar distribution pattern. This finding is not compatible with the conclusion, suggested by earlier studies, that the transcribed and nontranscribed parts of the rRNA genes are located at different sites within the nucleoli or in different nucleolar components.