title: Pathogenesis of Sarcocystis falcatula (Apicomplexa: Sarcocystidae) in the budgerigar (Melopsittacus undulatus). IV. Ultrastructure of developing, mature and degenerating sarcocysts.
abstract: Sarcocysts in cardiac and skeletal muscles of budgerigars (Melopsittacus undulatus) were examined transmission electron microscopically 5 to 168 days after experimental infection with Sarcocystis falcatula. The ultrastructure of the primary cyst wall, amorphous substance, metrocytes and bradyzoites in developing, degenerating and mature sarcocysts is described and compared with precystic merozoites studied previously. Sufficient morphologic differences between precystic merozoites, metrocytes and bradyzoites (cystozoites) were found which seem to justify their semantic differentiation. Significant differences in immature and mature primary cyst wall morphology were encountered. If primary cyst wall morphology is to be used in determination and differentiation of species of Sarcocystis, then caution must be used to employ only mature sarcocysts.
authors.affiliation: Department of Pathology and Laboratory Medicine, College of Medicine, Texas A & M University, College Station 77843-1114.
authors.forename: P J
authors.initials: PJ
authors.lastname: Neill
authors.forename: J H
authors.initials: JH
authors.lastname: Smith
authors.forename: E D
authors.initials: ED
authors.lastname: Box
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000469:parasitology*; D006321:Heart / Q000469:parasitology*; D008854:Microscopy, Electron; D009132:Muscles / Q000469:parasitology*; D009893:Opossums / Q000469:parasitology; D010240:Parakeets / Q000469:parasitology*; D011563:Psittaciformes / Q000469:parasitology*; D012522:Sarcocystis / Q000302:isolation & purification* / Q000648:ultrastructure; D012507:Sarcoidosis / Q000469:parasitology / Q000662:veterinary*