Japanese Journal of Veterinary Research;Volume 18, Number 3

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STUDIES ON ECHINOCOCCOSIS XXIII : ELECTRON MICROSCOPICAL OBSERVATIONS ON HISTOGENESIS OF LARVAL ECHINOCOCCUS MULTILOCULARIS

SAKAMOTO, Tsukasa;SUGIMURA, Makoto

Permalink : http://hdl.handle.net/2115/1963
JaLCDOI : 10.14943/jjvr.18.3.131

Abstract

Through the light- and electron-microscopical investigations on the histogenesis of larval Echinococcus multilocularis at 5~60 days after the inoculation, the following results were obtained. The cyst wall at the initial unilocular stage, 5~7 days after the inoculation, is composed of 2 types of cells ; the immature syncytial cells, and the light-stained undifferentiated cells with many polysomes. The latter show active mitosis. The wall of the multilocular cysts without a cuticular layer after 7~14 days comprises light- and dark-stained undifferentiated cells, and the syncytial cells. The dark-stained undifferentiated cells, which contain small mitochondria and polysomes, manifest active mitosis. The initial formation of the cuticular layer begins at the stage later than about 14 days. The cyst wall at this stage is constructed by the cells similar to those at the early stage, but many microvilli and terminal web-like structures are more distinctly demonstrable in the syncytial cytoplasm. At the stage of brood capsule and protoscolex formations, new types of cells are confirmed to appear ; the asteroid transforming cells, the muscle cells, the glycogenstoring cells, and the reticular interstitial cells. These cells can be distinguished from one another by the appearance of myofilaments, glycogen particles and mitochondria, respectively. The perikaryon of the syncytial cell removes to the inside of the germinal layer and is distant from its distal syncytial cytoplasm. Brood capsule formation originates in the massive accumulation of the dark-stained undifferentiated cells proliferated. A lumen surrounded by the syncytial cells, which line the brood capsule and possess the microvilli, is established at the center of the cellular accumulation. At first, the anlage of protoscolex manifests also the massive accumulation of proliferated dark-stained undifferentiated cells on the brood capsule wall. The anlage protrudes gradually into the lumen of the brood capsule. The types of constituent cells of the brood capsule wall and protoscolex show a strong resemblance to those of the cyst wall.

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