Ultrastructure of the Cysts of Sarcocystis Tarandivulpes from Skeletal Muscle of Reindeer (Rangifer Tarandus Tarandus)

Abstract

The cysts of S. tarandivulpes were found to be limited by a unit membrane which has been called the cyst membrane. The surface of the cysts was covered by closely packed and hexagonally arranged knob-like protrusions. The protrusions were 0.6–1.2 μm long and had an elliptical cross section. At the base of and between the bases of the protrusions the cyst mem brane was raised into low anastomosing folds which delineated shallow compartments. Between the folds the cyst membrane formed small vesicle-like invaginations into the cyst. On the apical part of the protrusions the cyst membrane had a smooth contour and was underlined by 2 layers of electron-dense material. Cyst ground substance divided the interior of the cyst into compartments containing either metrocytes or cystozoites. Cystozoites undergoing endodyogeny were present among the nondividing cystozoites. Some new terms were introduced to denote structures at the border of the cyst. The old terms are reviewed and the structural resemblance between S. tarandivulpes and S. odocoileocanis from Odocoileus virginianus is discussed.

Samandrag

Cystene var avgrensa av ein typisk elementærmembran som ein har kalla cystemembranen. Cysteoverflata var dekka av tettsitjande, utvekstar (projeksjonar) med eit ellipseforma tverrsnitt. Projeksjonane var frå 0.6–1.2 μm lange. Ved basis av projeksjonane og i romma mellom dei danna cystemembranen låge anastomoserande mikrofoldar og små invaginasjonar. Grunnsubstans danna eit lag perifert i cystene og delte det indre av cystene opp i talrike kammer som inneheldt anten metrocytar eller cystozoitar. I nokre av cystozoitane føregjekk det ein delingsprosess (endodyogeni). Cystene til S. tarandivulpes hadde ein liknande morfologi som cystene til S. odocoileocanis frå kvithalehjort. I omtalen av cystene er det delvis nytta ein ny terminologi, og denne vert samanlikna med den etablerte terminologien.