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Freshwater Crayfish 12(1): 933-934 (1999)


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Light and electron microscopical studies on porcelain disease (Thelohania contejeani) in noble crayfish (Astacus astacus)

Hoffmann RW, El-Matbouli M, Oidtmann B and Fischer H  e-mail link

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Porcelain disease is a chronical microsporidean infection caused by Thelohania contejeani which affects Astacus astacus, A. leptodactylus, Austropotamobius pallipes and Orconectes limosus in Europe. Clinical signs are unspecific; only in late stages white abdominal muscles, disturbed behaviour and loss of claws can be observed. By light microscopy mature spores of Thelohania can be detected in nearly all organs. However, the parasite is restricted to muscle tissue alone. In infected skeletal muscles the cross striation is destroyed, and the cytoplasm is thickened and filled by masses of spores. Finally the muscle fibre disrupts distributing the spores into the surrounding tissue, from where they can be further transported with the haemolymph. In muscle cells of organs, esp. the gut and ovaries, affected cells are less frequent. In the heart, only small infected foci are observed. In other parenchymatous tissues such as the hepatopancreas they can only be found intercellularly and in the mixocoel, but never inside of parenchyma cells. By electron microscopy a well structured spore with three outer layers, a polar filament, the nucleus containing sporoplasm and a vacuole can be differentiated. The development of spores starts with an uninuclear meront, followed by a diplokaryon. Inside of a meront, plenty of diplokaryons develop vegetatively, resulting in so-called plasmodia. A plasmodium can divide further or start a sporogony. Early sporonts are characterized by high amounts of ribosomes and the appearance of electron dense material on the cellular membrane. Inside of these sporonts (formerly called pansporoblasts, more recently sporophorous vesicles) eight sporoblasts and spores are formed which is characteristic for the genus Thelohania. The mode of transmission of the infection from one animal to another could not be exactly clarified, only a direct infection by feeding or injection of spore containing material could be excluded.

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Hoffmann RW, El-Matbouli M, Oidtmann B and Fischer H. (1999). Light and electron microscopical studies on porcelain disease (Thelohania contejeani) in noble crayfish (Astacus astacus). Freshwater Crayfish 12(1):933-934. doi:



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