Abstract

A morphological study on the ultrastructures of body wall and the nervous system of Clonorchis sinensis was conducted. For this study, liver flukes were collected from the liver of rabbit six months after the infection with metacercariae obtained from the fresh water fish, Pseudorasbora parva. The collected materials were washed with 0.85 percent saline solution and then immediately moved to cold 2.5 percent glutaraldehyde buffered with 0.1 M Millonig's phosphate buffer (pH 7.4). The materials were dissected into appropriate pieces in the fixative about 30 minutes after beginning of the fixation. Two hours later the materials were rinsed several times with the buffer and were fixed with cold, buffered 1 percent osmium tetroxide(OsO(4)) for 2 hours. The fully fixed tissue blocks were dehydrated in a series of graded concentrations of acetone and were embedded in Epon 812 mixture. Thin sections obtained from Sorvall MT-2 ultramicrotome were stained with uranyl acetate and Reynold's lead citrate. Observations of the sections were carried out with Hitachi HS-7S electron microscope. The following structures are newly identifed in a series of observations. The mid-abdominal integument of the fluke is more thicker(-6 micrometer) than the dorsal side(about 3 micrometer). Although it is so far known that only surface and epithelia of the suckers, pharynx, and the oesophagus are composed of integumental, anuclear layer, it is newly found that epithelium of the excretory pore also consists of integumental, anuclear layer. There are lot of microvilli in the dorsal outer surface of the oral sucker. A kind of ducts accumulated with unknown secretory granules are present within the parenchyrna around both of the oral suckers and the pharynx. The nerve endings are distributed to the integument of the body where sensory hairs are projected outward. The sensory hairs are rarely distributed throughout the whole integument, but a little more in the surroundings of both suckers. The sensory hairs are attached to the base of the sheath by a circular septate desmosome. No rootlet structure is observed but the upper part of the basal body is attached to the peripheral desmosome by transverse fibres. The mitochondria and the vesicles are present within the hair cavity. The nerve fibres are also found to be myelinated at least in main axons.