FINE STRUCTURE OF OYSTER PATHOGEN MINCHINIA NELSONI (HAPLOSPORIDA HAPLOSPORIDIIDAE)

The fine structure of plasmodia and spores of the sporozoan Michinia nelsoni, pathogenic to the oyster Crassostrea virginica, is described. Plasmodial nuclei have fibers of 150 to 180 Å attached to centriolar plaques such as have been described for other microorganisms. Electron-dense elements with internal structure were found singly and in groups in the cytoplasm. The groups appeared to be areas of elaboration or formation. Mitochondria showed fibers reminiscent of intramitochondrial DNA fibers described by other investigators. The spores contained a prominent Golgi apparatus which probably corresponds to the anterior cytoplasmic spherule of the literature on Minchinia sp. Spore wall ontogeny is described in detail. © 1968.