Immunohistochemical analysis of cytokeratin 7 expression in resting and proliferating biliary structures of rat liver

Hepatology. 2005 Oct;42(4):863-70. doi: 10.1002/hep.20858.


Cytokeratins are the largest subfamily of intermediate filament proteins and include more than 20 different gene products, which are expressed in an epithelial tissue-specific manner. We studied by immunohistochemistry and confocal microscopy the distribution of cytokeratin subtypes in the biliary system of adult rat liver. A cytokeratin (CK)19+/7- cholangiocyte population was observed in the smaller branches of the biliary tree including the canals of Hering. They proliferated after 2-acetaminofluorene (AAF) administration, although later the typical oval cells expressed CK7. This observation suggests that cholangiocytes with this cytokeratin phenotype may harbor adult hepatic stem cells. The CK19+/7- cholangiocytes were not present in the rat liver at birth, but developed postnatally. Similar cell populations were not observed in human livers. In conclusion, we propose that the CK19+/7- phenotype may be characteristic for adult hepatic stem cells in rat liver and that these cells are generated de novo after birth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2-Acetylaminofluorene / analogs & derivatives
  • 2-Acetylaminofluorene / pharmacology
  • Age Factors
  • Animals
  • Bile Ducts, Intrahepatic / cytology*
  • Bile Ducts, Intrahepatic / growth & development
  • Bile Ducts, Intrahepatic / metabolism*
  • Biomarkers / metabolism
  • Cell Division / drug effects
  • Humans
  • Immunohistochemistry
  • Keratin-7
  • Keratins / metabolism*
  • Liver / cytology*
  • Liver / growth & development
  • Liver / metabolism*
  • Male
  • Rats
  • Rats, Inbred F344
  • Stem Cells / cytology
  • Stem Cells / metabolism


  • Biomarkers
  • KRT7 protein, human
  • Keratin-7
  • Keratins
  • 2-Acetylaminofluorene