Ultrastructural features of the gametogenic and sporogonic development of

Stages of gametogony and sporogony of the haemogregarine Hepatozoon sipedon, an apicomplexan parasite of the Northern water snake, Nerodia sipedon sipedon, were studied in the mosquito, Culex pipiens, by electron microscopy. Four days after mosquitoes fed on an infected snake, microgamonts and macrogamonts were observed in syzygy in parasitophorous vacuoles within fat body cells of the haemocoel. During microgametogenesis, two biflagellated microgametes were formed, one of which fertilized the macrogamete. After fertilization, zygotes increased rapidly in size, accumulating reserve material in the form of lipid inclusions. Beginning at 16 days post-feeding (PF), the nucleus of the immature oocyst underwent multiple divisions in the first stage of sporoblast formation. Small crystalloid bodies initially appeared in the cytoplasm of the dividing oocyst at 20 days PF. At 24 days PF, the oocyst contained hundreds of sporoblasts, each of which matured as early as 28 days PF into thick-walled sporocysts containing eight sporozoites and a large residual body. Sporozoites contained a large crystalloid body comprised of tightly-packed particles assembled in a paracrystalline array. The use of ultrastructural characters in the differentiation of Hepatozoon species is discussed in context with the current phylogenetic hypotheses of adeleorin taxa

Workshop 4A: Protozoa of fish

No abstract availabl

n. sp. (Apicomplexa: Aggregatidae) : a coccidian parasite of the kidney of blue missels, species of

Three of 91 mussels, taken from Pacific coastal waters in Nanaimo, British Columbia, were infected with a new species of coccidian parasite. Gamogonic and sporogonic development were observed in renal tubular epithelial cells. Mature macrogametocytes were crescent-shaped. Oocysts sporulated within the host. Mature oocysts were spherical, mean 23.9 μm (range 22-25 μm) with approximately 24 ellipsoidal sporocysts (approximately 6 x 3 μm), each of which contained two sporozoites. Ultrastructural features of immature and mature macrogametocytes are described. Although found in all five populations of mussels from various locations in British Columbia, prevalence of infection was usually less than 16%, intensity of infection was usually light (less than 50 coccidia per histological section of kidney tissue), and evidence of associated pathology was not observed

Pathology associated with endogenous development of haematozoa in birds from southeast Queensland

A study was undertaken on the pathology and associated schizont morphology of apicomplexan species of avian haematozoa. Some 32 birds from the families Artamidae, Meliphagidae, Oriolidae, Podargidae, Columbidae, Alcedinidae and Psittacidae were identified as having schizonts in various tissues. Based on blood stages observed, the probable relationship to tissue stages was considered. The majority of schizonts were referable to the genera Leucocytozoon and Haemoproteus . The comparative morphology of tissue stages previously described in the literature is discussed and the involvement of protozoa other than haematozoa considered. The naturally occurring infections in wild birds described in this study represent previously unreported data on the life-cycle stages involved. Some schizonts measured up to 640 mum. While pathological changes in some hosts were noticeable, in others no significant findings were observed. The role of endogenous stages in avian morbidity is discussed briefly