Interactions between epithelial and mesenchymal cells in intrahepatic peribiliary glands in normal and hepatolithiatic livers.

The anatomy and pathology of the intrahepatic peribiliary glands were evaluated. In this study, we ultrastructuraly examined the peribiliary glands of normal and hepatolithiatic livers using common and serial ultrathin section observations. It is well known that these glands proliferate markedly in hepatolithiasis. These glands were composed of several acini surrounded by thickened and multilayered basement membranes, and there were mesenchymal cells (the majority were fibroblasts) in the periacinar fibrous connective tissue. Some cytoplasmic processes of acinar epithelial cells and mesenchymal cells in the periacinar connective tissue were in close contact with each other within the thickened and multilayered basement membranes. Such cell-to-cell interaction was most frequent in cases of hepatolithiasis, in which peribiliary glands proliferated markedly. In hepatolithiatic livers, some unmyelinated nerve fibers or axonal button profiles were in close contact with periacinar mesenchymal cells and also with cytoplasmic processes of glandular epithelial cells. Such contacts were rare in normal livers. These findings suggest that such epithelial and mesenchymal cell interactions and innervations play a part in the normal regulation of peribiliary glands and also in the proliferation of peribiliary glands in hepatolithiasis.