Answers are grounded in this paper and cite their sources.
The presence of extrachromosomal nucleoli in amphibian oocytes has permitted isolation and electron microscopic observation of the genes coding for ribosomal RNA precursor molecules. Visualization of these genes is possible because many precursor molecules are simultaneously synthesized on each gene. Individual genes are separated by stretches of DNA that apparently are not transcribed at the time of synthesis of precursor rRNA in the extrachromosomal nucleoli.
No takes yet. Share an insight, caveat, or question.
Miller et al. (1969) studied this question.
Synapse has enriched 5 related papers. Consider them for comparative context: