Ultrastructural studies on the integument of digenetic trematodes were investigated by several workers (Senft et al., 1961; Bjorkman and Thorsell, 1964; Burton, l966; Erasmus, l968; Morris and Threadgold, 1967, l968). Clonorchis sinensis is a common parasite of human beings in the Far East. But as far little has been written on ultrastructure of the integument of this parasite. This study was carried out systematically to elucidate the ultrastructure of the integument of adult C. sinensis, and the results are summarized as follows: The integument of C. sinensis was organized in two parts; the epidermis and the muscular layer. The apical surface and basal surface of the epidermis were covered with typical plasma membrane and irregularly invaginated from the surface. Plasma membrane at perisuckers was extremely folded and appeared as if the epidermis might be divided with the layer. The syncytial epidermis contained mitochondria and numerous secretory bodies, and which was connected by cytoplasmic processes to nucleated epidermal cells lying in the parenchyma. The mitochondriae, the secretory bodies, the granular endoplasmic reticulum, the Golgi bodies and the free ribosomes were present in the perinuclear cytoplasm of epidermal cells, but no organelle was observed in processes of epidermal cell except some secretory bodies. The fibrous layer consists of argentophile fiber and collagenous fiber, in which the circular muscle bundles and longitudinal muscle bundles were embedded. Bundles of muscle fiber are weIl developed at the perisucker, and mitochondriae in this portion contain many cristae as compared with any other parts of C. sinensis.
parasitology-helminth-trematoda-Clonorchis sinensis ; ultrastructure ; electronmicroscopy

The present study was undertaken to observe the changes of hepatocyte and biliary epithelium in the liver of guinea pigs infected with C. sinensis. Ten guinea pigs infected with 500 metacercariae of C. sinensis each were reared for 11 weeks. After sacrifice, the liver tissues were processed both for conventional light microscopy and for electronmicroscopy. The following results were obtained by light and electronmicroscopic observation of these tissue preparations. The dilatation of bile ducts with chronic inflammatory cell infiltration and fibrosis, and flattening of lining epithelium were observed by light microscopy. Bile duct showed a single low columnar or cuboidal epithelium and subepithelial small round cell infiltration. Papillary proliferation, adenomatous hyperplasia and increase of goblet cells in the subepithelial glands were also noted in some areas of bile ducts. Occasionally, small fibrous nodules in the portal tract replacing bile ducts, surrounded by a heavy infiltrate of small round cells and neutrophils were observed. On light microscopic examination, no cellular damages were seen in the liver cells except mild fatty degeneration. Electronmicroscopic examination of the biliary epithelium revealed increased mucin granules, cytoplasmic projection into lumen, decreased microvilli and obstruction of bile canaliculi. Indistinct and/or irregular appearances of intercellular lateral interdigitation were observed in most of biliary epithelium. On the electronmicrographs of hepatocytes, dilation of endoplasmic reticulum(ER) and destruction of cristae in some mitochondriae were prominent features. Disappearance of cytoplasmic organells and dilatation of bile canaliculi were also monitored. Endothelial cells in the sinusoids were remained intact.
parasitology-helminth-trematoda ; Clonorchis sinensis ; guinea pig ; pathology ; bile duct ; ultrastructure-electronmicroscopy ; fibrosis ; hyperplasia ; goblet cell