The DNA and RNA molecules were spread according to a special method, the Miller-technique. a, b rRNA-genes within the nucleoli. These genes are repetitive and always oriented in the same way. They are separated by non-transcribed segments. At each gene work numerous polymerases simultaneously like on a conveyor-belt. The partially ready transcripts appear therefore as little 'fir-trees' also called 'MILLER-trees'. Next to the start of the transcription are the 'branches' shortest (only a small part has been transcribed), shortly before the termination are they longest. The transcribed segments are clearly longer than the detached transcription products. This is on one hand caused by the RNA forming complexes with proteins, on the other hand on a tendency to tangle up.
The transcription of several genes in the nucleus. They are of different lengths, do not occur as tandems and are always of the same orientation. The non-transcribed segments are also of different lengths. (S. BERGER, H.-G. SCHWEGER, 1975; S. BERGER; D. M. ZELLMER, K. KLOPPSTECH, G. RICHTER, W. L. DILLARD, H.-G. SCHWEIGER, 1978)