Cytokeratin intermediate filaments of rat hepatocytes: Different cytoskeletal domains and their three-dimensional structure

Authors

  • Yoshinori Katsuma,

    1. Department of Pathology, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada K1H 8M5
    2. Research Center, Hotel-Dieu Hospital, Laval University, Quebec, Canada G1R 2J6
    3. Aiseikai Yamashina Hospital, Yamashina-ku, Kyoto, Japan
    Search for more papers by this author
  • Normand Marceau,

    1. Department of Pathology, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada K1H 8M5
    2. Research Center, Hotel-Dieu Hospital, Laval University, Quebec, Canada G1R 2J6
    3. Aiseikai Yamashina Hospital, Yamashina-ku, Kyoto, Japan
    Search for more papers by this author
  • Masaharu Ohta,

    1. Department of Pathology, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada K1H 8M5
    2. Research Center, Hotel-Dieu Hospital, Laval University, Quebec, Canada G1R 2J6
    3. Aiseikai Yamashina Hospital, Yamashina-ku, Kyoto, Japan
    Search for more papers by this author
  • Samuel W. French M.D.

    Corresponding author
    1. Department of Pathology, Faculty of Health Sciences, University of Ottawa, Ottawa, Canada K1H 8M5
    2. Research Center, Hotel-Dieu Hospital, Laval University, Quebec, Canada G1R 2J6
    3. Aiseikai Yamashina Hospital, Yamashina-ku, Kyoto, Japan
    • Professor and Chairman, Department of Pathology, Faculty of Health Sciences, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5
    Search for more papers by this author

Abstract

A new method of visualizing the three-dimensional architecture of the cytokeratin filaments of the intact rat hepatocyte in situ has been achieved. Frozen sections of liver cut 10 μm thick were serially extracted to remove all elements of the cells except the intermediate filaments. Parallel sections were stained with monoclonal antibodies to the two main cytokeratins found in bile duct and liver cells. Immunofluorescent antibody and immunogold electron microscopy techniques were used to identify the proteins morphologically. Several new observations resulted from these studies. The pericanalicular sheath of intermediate filaments was visualized using steropairs as an uninterrupted branching tubular structure composed of cytokeratins located in the cell cortex of adjacent hepatocytes. Intermediate filaments in the cell cortex formed a distinct sheet of matted filaments which enveloped the entire hepatocyte. The cortical intermediate filaments were in continuity with the pericanalicular sheath and the filaments located within the cytoplasm. The intermediate filaments are attached to the centrioles and appeared to tent the nuclear lamina-pore complex at points of contact. Monoclonal antibodies to rat liver intermediate filament cytokeratins (CK49 and CK55) each stained intermediate filaments located in the cell cortex, within the cytoplasm and at the nucleus. By immunogold staining, some of the intermediate filament filaments were shown to contain both cytokeratins. Filaments which did not stain were thought to be either actin at the cell periphery or nuclear lamins around the nucleus. It is concluded that the cytokeratins form a specialized framework for the cell cortex, canaliculus, centrioles and the nucleus of hepatocytes. The filaments run continuously throughout the cytoplasm without terminating.

Ancillary