Japanese Journal of Veterinary Research;Volume 17, Number 3

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STUDIES ON ECHINOCOCCOSIS XXI : ELECTRON MICROSCOPICAL OBSERVATIONS ON GENERAL STRUCTURE OF LARVAL TISSUE OF MULTILOCULAR ECHINOCOCCUS

SAKAMOTO, Tsukasa;SUGIMURA, Makoto

Permalink : http://hdl.handle.net/2115/1924
JaLCDOI : 10.14943/jjvr.17.3.67

Abstract

The general fine structure were studied on fully developed larval Echinococcus multilocularis in cotton rats by use of electron microscope. The tegument of protoscolex consists essentially of the distal, syncytial cytoplasm (tegumental cytoplasm) of tegumental cell in the parenchyma. The surface of tegument is covered with spinous projections, on the rostellum and suckers, and with knob-like projections, on the posterior part of protoscolex. The tegumental cytoplasm contains vesicles and tubules with or without electron-opaque material. The cytoplasmic continuity is recognized between the tegumental cytoplasm and the perinuclear cytoplasm of tegumental cell. The basement membrane is found beneath the basal plasma membrane of tegumental cytoplasm. The zone of fibrous interstitium underlaying the basement membrane is continuous with the extracellular interspace in the parenchyma. The muscle cells in the parenchyma and sucker of protoscolex, brood capsule and germinal layer comprise the perinuclear cytoplasm with ribosomes and the projections which consist of the amyofibrillar portion with glycogen particles and myofibrillar one with myofibrils. The cells containing numerous alpha particles of glycogen in the perinuclear cytoplasm and the projections, are found in the above-mentioned places. The sucker established by a mass of muscles and is surrounded with a basement membrane. In the tegumental cytoplasm of rostellum and suckers, the sensory endings are confirmed and show the bulb-like expansion with a cilium-like terminal process. Unmyelinated nerve fibers and those synaptic junctions are recognized among the muscle cells in the parenchyma and the sucker. The nerve fiber contains mitochondria and vesicles, and the synaptic junction has many vesicles accumulating on one side of it. The flame cell in the parenchyma has a bundle of cilia characterized by the general pattern (9+2) and the bundle is enveloped with the extension of membraneous cytoplasm. The wall of the excretory duct is made up of the syncytial cytoplasm showing the same character as the tegumental cell. The inner surface of the wall of the brood capsule is covered with the syncytial cytoplasm possessing the villiform projections (microvilli). The perikarya of the syncytial cytoplasm, muscle cells, glycogen-containing cells, and excretory ducts occur along the outer side of the syncytial cytoplasm. The interspace among the above elements is filled with fibrous interstitial material (fibrous interstitium). The cuticular layer of the cyst wall is composed of extracellular, fine, fibrous material which distributes quite equally without lamination. The outer surface of the germinal layer is overlain with the distal, syncytial cytoplasm resembling tegumental cytoplasm. The distal, syncytial cytoplasm of the germinal layer containing a number of mitochondria attaches to the cuticular layer, and is ornamented with a number of well developed microvilli which invade into the cuticular layer. The perikarya of the syncytial cytoplasm, muscle cells, glycogencontaining cells, excretory ducts and fibrous interstitium are recognized along the inner side of the distal, syncytial cytoplasm. Those components are continuous, without a line of distinction, to those of the adjoining brood capsule wall.

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