Ultrastructure of the Microsporidian Thelohania (Agmasoma) penaei in the Pacific white Shrimp (Litopenaeus vannamei)

Abstract

The structure of Thelohania (Agmasoma) penaei, a microphoridian parasite of farm-reared Pacific white shrimp (Litopenaeus vannamei) was examined with electron microscopy. Infected abdominal muscles and hepatopancreas were used for this study. Development was found in the cells of both tissues of infected shrimp. Earliest stages observed were limited to diplokaryotic cells. Sporogony was a series of three binary fissions, each producing unikaryotic cells within the sporophorous vesicle. Mature spores were ovoid, measuring 3.61 x 2.09 µm. The polar filament had eight coils at 0.19-1.06 µm in diameter.