Structures of nucleolus and transcription sites of rRNA genes in rat livercells

We observed the ultrastructure of nucleolus in rat liver cells by conventio nal electron microscopy, and employed cytochemistry NAMA-Ur DNA specific st ain method to analyze the distribution and position of nucleolar DNA in sit u. The results showed that nucleolar DNA of rat liver cells comes from nucl eolus-associated chromatin, and continuously extends in the dense fibrillar component (DFC) of nucleolus, localizes at the periphery of fibrillar cent er (FC) and in DFC. Furthermore, by employing anti-DNA/RNA hybrid antibodie s, we directly and selectively labeled transcription sites of rRNA genes an d testified that localization of transcription sites not only to DFC but al so to the periphery of FC.