Structures of nucleolus and transcription sites of rRNA genes in rat liver cells

We observed the ultrastructure of nucleolus in rat liver cells by conventional electron microscopy, and employed cytochemistry NAMA-Ur DNA specific stain method to analyze the distribution and position of nucleolar DNAin situ. The results showed that nucleolar DNA of rat liver cells comes from nucleolus-associated chromatin, and continuously extends in the dense fibrillar component (DFC) of nucleolus, localizes at the periphery of fibrillar center (FC) and in DFC. Furthermore, by employing anti-DNA/RNA hybrid antibodies, we directly and selectively labeled transcription sites of rRNA genes and testified that localization of transcription sites not only to DFC but also to the periphery of FC.