AN EXPERIMENTAL APPROACH TO THE PATHOGENESIS OF PIPESTEM FIBROSIS (SYMMERS FIBROSIS OF THE LIVER)

Pathogenesis of schistosomal hepatic fibrosis ('' pipestem '' fibrosis of the liver) was investigated by means of the murine model. Although worm load appears as the main pathogenetic factor, alone it is not su fficient to produce that characteristic lesion. By comparing the findi ngs in animals with heavy and prolonged Schistosoma mansoni infection, which developed or not '' pipestem '' fibrosis, it was observed that the lesion was more frequent in intact animals than in the splenectomi zed one. However the size of the spleen, the number of recovered worms , the number of eggs per gram of liver tissue, the level of serum idio type and anti-idiotype antibodies, the sii-e and volume of periovular granulomas formed in the liver all that failed to show statistically s ignificant differences between the two groups. After analysing all the se data, other factors, that apparently have been hitherto negleted, r ested to explain the findings. Among them, the timing and sequence of the egg-induced intrahepatic vascular changes seemed crucial. The sequ ential development of intrahepatic portal vein obstruction, followed b y the opening of periportal collateral veins and the continous arrival of schistosome eggs going to be lodged into the latter, appeared as e ssential steps in the pathogenesis of '' pipestem '' fibrosis.