Abstract
The fine structure of spore excystment, plasmodial development, and sporoblast formation phases of the life cycle of the sporozoanHaplosporidium lusitanicum haplosporidian species recently described by Azevedo (1984), pathogenic to the plate limpetHelcion pellucidus (Gastropoda) is described. After liberation from the spore wall, the uninucleate amoebula penetrates the host and is first found in the connective tissue in contact with the periphery of the ovary and hepatopancreas. The amoebula develops into a plasmodium by enlargement and nuclear multiplication as evidenced by mitotic figures each consisting of a bundle of microtubules attached to spindle pole bodies situated in the nucleoplasm near the nuclear envelope. The cell becomes successively binucleated, tetranucleated, etc.. forming a multinucleated sporont containing several hundred nuclei. Each nucleus contains a nucleolus and obvious chromatin.
In the next phase a very irregular membranous system and some Golgi complexes begin to differentiate in the cytoplasm. Then, each nucleus and a portion of surrounding cytoplasm is encircled by a limiting membrane which arises from fusion of Golgi vesicles. In sporonts several hundred sporoblasts are thus formed.
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Azevedo, C., Corral, L. & Perkins, F.O. Ultrastructural observations of spore excystment, plasmodial development and sporoblast formation inHaplosporidium lusitanicum (Haplosporida, Haplosporidiidae). Z. Parasitenkd. 71, 715–726 (1985). https://doi.org/10.1007/BF00926797
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DOI: https://doi.org/10.1007/BF00926797