Animalia 4 Animals 4 Base Sequence 4 Blotting, Northern 4 Cells, Cultured 4 Ctenomys 4 Electrophoresis, Polyacrylamide Gel 4 Evolution, Molecular 4 Introns 4 Male Mammalia Mammalian cells 4 Mice 4 Models, Genetic 4 Molecular Sequence Data 4 Molecular Weight 4 Nucleic Acid Conformation 4 Organ Specificity 4 RNA 28s 4 RNA Precursors 4 RNA Splicing 4 RNA cleavage 4 RNA precursor 4 RNA processing 4 RNA, Ribosomal, 28S 4 Rats 4 Repetitive Sequences, Nucleic Acid 4 Ribosomal RNA processing 4 Rodentia 4 Testis 4