Abstract
Atypical bile ducts induced by 0.1% ethionine in choline deficient diet (ECD) were biologically and histologically examined in rat liver. At 1 week after administration, enlargement of nucleolus and central lobular fatty change were observed in hepatic cells. At 2 weeks, there were diffuse and tubular proliferation of oval cells in periportal and along sinusoidal regions. The fatty droplets were large in size and expanded throughout the lobules. At 4 weeks oval cells became more conspicuous, occasionally formed duct structures (bile duct proliferation), and atypical bile ducts were observed with obvious border and secretion of mucin. The neoplastic nodules were first recognized at this time. At 8 weeks the oval cells increased more prominently, and there were many atypical bile ducts with fibrosis. At 12 weeks (group 50% ECD), atypical bile ducts and neoplastic nodules were more conspicuous. In the recovery period, the number of oval cells was much less than during administration, and neoplastic nodules were hardly seen. The atypical bile ducts, however, showed large nodular expansions in the periportal region, being much more conspicuous than those during administration. Macroscopically, the bile duct lesions could be seen as transparent small and whity nodules and could be readily distinguished from neoplastic nodules which were milky white in color. The cell proliferation activity of the bile duct lesions showed a higher value in recuperating rats than in administered ones.
From the above findings it was confirmed that the atypical bile ducts are induced in association with oval cell proliferation, and that the cell proliferation activity and covering area did not show reduction by removal of the exciting agent, and that the lesion has the ability of autonomous development.
