title: Electron microscopic radioautographic study on protein synthesis in amitotic hepatocytes of the aging mouse.
abstract: Ten groups of aging mice, each consisting of three individuals, from fetal day 19 to postnatal month 24, were injected with (3)H-leucine and killed 1 h later; the livers were processed for light and electron microscopic radioautography. On radioautograms obtained from each animal, amitotic nuclear divisions and resulting binucleate hepatocytes were detected and compared to mononucleate hepatocytes. From the results, it was demonstrated that only a few hepatocytes showing amitotic nuclear divisions were found labeled with the precursor demonstrating protein synthesis. However, the numbers of silver grains showing incorporations of labeled precursors in respective amitotic cells were very few. It was clarified that the amitotic cells did not synthesize such macromolecules as mononucleate hepatocytes did. On the other hand, more binucleate cells were found than amitotic cells. Protein synthesis in karyoplasm and cytoplasm in both mononucleate and binucleate cells increased from the perinatal stage, reaching the maxima at adult stage, then decreased to the senescent stage. Grain counts revealed that synthesized proteins were more abundant in binucleate cells than in mononucleate cells at the respective aging stages.
authors.affiliation: Department of Anatomy and Cell Biology, Shinshu University School of Medicine, Matsumoto, Japan. nagatas@po.cnet.ne.jp
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Nagata
authors.forename: Hongjun
authors.initials: H
authors.lastname: Ma
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001345:Autoradiography / Q000379:methods; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000254:growth & development; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D014316:Tritium
chemical_list: D014316:Tritium; D007930:Leucine