Expression of pancreatic alpha‐amylase protein and messenger RNA in hilar primitive bile ducts and hepatocytes during human fetal liver organogenesis: an immunohistochemical and in situ hybridization study

Abstract

This study was conducted to evaluate the expression of pancreatic digestive enzymes in hilar bile ducts and hepatocytes during human fetal liver organogenesis. We investigated the expression of pancreatic alpha-amylase protein and messenger RNA (mRNA) in hilar primitive bile ducts and hepatocytes by immunohistochemistry and in situ hybridization techniques, using 11 human fetal livers of various gestational ages. The specificity of the immunohistochemistry and in situ hybridization procedures was confirmed by Western blot analysis and in situ hybridization using sense probes, respectively. Immunoreactivity of pancreatic alpha-amylase protein and expression of pancreatic alpha-amylase mRNA were present not only in the primitive ductal cells of the hilar region including the ductal plate, remodelling bile ducts and remodeled bile ducts but also in primitive hepatocytes of the hilar region, though the immunoreactivity and mRNA signals in the primitive hepatocytes disappeared in the third trimester. There was perfect correlation between immunohistochemistry and in situ hybridization. These results suggest that primitive biliary cells and hepatocytes of the hilar region in the human fetus do express pancreatic alpha-amylase protein and mRNA, and that the primitive biliary epithelial cells and hepatocytes in the hilar region share a common cell lineage with exocrine pancreatic cells.