Ultrastructure of the cysts ofSarcocystis grueneri from cardiac muscle of reindeer (Rangifer tarandus tarandus)

Abstract

Cysts ofSarcocystis grueneri from cardiac muscle of reindeer (Rangifer tarandus) in Norway were examined by transmission electron microscopy. The limiting unit membrane of the cyst proper formed regularly spaced invaginations into the cyst at numerous sites coinciding with interruptions in the underlying osmiophilic layer. The primary cyst wall formed numerous strip-like, sinuous protrusions, which were 30–40 nm thick, 150–300 nm wide and up to 4.5 μm long, and were running in paralled with the surface of the cyst. Generally the protrusions were arranged in several closely spaced layers compressed against the cyst. The nature and arrangement of the protrusions render them undetectable by light microscopy. Cyst ground substance divided the interior of the cyst into compartments containing typical sarcosporidian metrocytes and cystozoites. The cysts ofS. grueneri from reindeer were ultrastructurally similar to cysts reported from red deer, roe deer and moose by other workers. The possibility that these cervids are hosts for a commonSarcocystis species is discussed.