Experimental Mechanical Jaundice: Morphological Aspects of Proliferation, the Possibility of Transformation and Involution of Epithelial Cells in the Bile Ducts

On an experimental model of obstructive jaundice in experimental rats, the cytological aspects of proliferation and the possibility of transformation of cholangiol cells into hepatocytes, as well as the cellular mechanisms of involution of the bile ducts, were investigated. The material was the liver of sexually mature rats (n=38) with 10, 20, and 25 days of cholestasis, in which the duct was recanalized during these periods and sacrificed on the 5th, 10th, 15th, 30th and 90th days after the second operation. Pieces of liver tissue were processed by conventional histological and electron microscopic methods. Ligation of the bile duct promotes rapid proliferation of the bile ducts, which correlates with the duration of cholestasis. In the early stages of the experiment (cholestasis for 10 days), the bile ducts occupy the peripheral sections of the lobules, by the 20th day, cholestasis penetrates deeply into the lobule, dismembering it into fragments, and by the 25th day, a picture of biliary cirrhosis develops. It was found that the proliferation of the bile ducts occurs due to the duct cells themselves, the transformation of cholangiol cells into "oval" cells or hepatocytes was not found. The transformation criteria were the shape, intracellular structures, and the state of the boundary plate and the basement membrane of the ducts. Consequently, bile duct cells (cholangioli) and hepatocytes, diverse in their function, showed absolute genetic heterogeneity. After the restoration of the outflow of bile, non-functioning ducts undergo destruction and decay. It has been shown that hepatic macrophages play an active role in cleansing the liver parenchyma from the products of cellular decay of the bile ducts, dead liver cells, as well as excess fibrillar structures. Activated Kupffer cells, due to the content of a large number of heterolysosomes, provide degradation, lysis and utilization of cellular and extracellular structures.

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