An experimental study on the mouse intraperitoneal inoculation of the adult worm of Clonorchis sinensis

ABSTRACT

The present experimental study was undertaken to observe the chronological change of the worm structure of Clonorchis sinensis and the pathological findings of the liver when this fluke was inoculated to the mouse intraperitoneally. The recovery rate, survival rate, location and size of the inoculated worms as well as the pathological changes of the liver were investigated for the comparison among the groups of mice, classified by number of worms and the duration of experiment. The results obtained were summarized as follows The recovery and survival rates of the worms decreased especially 28 days after the inoculation. Most of worms (90.l percent) were collected from the peritoneal cavity and some of worms were found tightly adherent to the capsules of the liver, spleen, stomach, intestine and diaphragm. There were no worms recovered penetrated in the parenchymes of these organs. The mean worm size after inoculation was smaller than that before inoculation. At the 10th day after the inoculation, the shrinkage of posterior portion of the worm body was observed. Remarkable atrophy in the reproductive organs of the worm, such as spermatheca, testes, vitelline glands and ovary was frequently observed at the 10th day of inoculation. Histopathologically the liver failed to show any parasitic worm inside the intrahepatic biliary system. However, multiple well formed egg-containing granulomas were present along the liver capsule. These necrotic granulomas were occasionally found under the fibrotic liver capsule. Focal necrosis and focal phlebitis together with vascular dilatation were prominent features seen in the liver. The bile duct in the liver showed mild dilation of the lumen, flattening of epithelial cells and periductal small round cell infiltration. Neither adenomatous hyperplasia nor portal fibrosis was seen in the whole experimental groups. Foci of intralobular micro-granulomas were found in some experimental animals. The worms recovered in the capsule of the liver were degenerated and necrotized. Usually, there were remarkable capsulitis and granuloma formation around the eggs.