Ultrastructure of the cysts of Sarcocystis rangi from skeletal muscle of reindeer (Rangifer tarandus tarandus)

Abstract

Mature muscle cysts of Sarcocystis rangi from Rangifer tarandus were examined by transmission electron microscopy. The long and slender cysts were located within skeletal muscle cells, and were bounded by a unit membrane, the cyst membrane. The cysts were provided with closely spaced flexible, hairlike surface processes, measuring up to 12.6 |im in length and 0.3 to 0.6 \lm in diameter. The projections had a smooth surface, whereas the cyst membrane formed numerous hexagonally packed vesicular invaginations between the bases of the projections. The cyst membrane was reinforced by an underlying thin layer of electron-dense material, except at the points where it was invaginated. Cyst ground substance formed a thin layer at the periphery of the cysts, filled the core of the projections, and formed thin septa that divided the interior of the cysts into numerous compartments. Most compartments contained a large number of tightly packed cystozoites, whereas a few metrocytes were forund in each of a few compartments at the periphery of the cysts. Some of the cystozoites multiplied by endodyogeny. The metrocytes displayed a vacuolation of their cytoplasm. The cysts of S. rangi were similar in surface morphology to the sarcocysts of certain other Sarcocystis species reported from other intermediate hosts.

Ultrastrukturen til cyster av Sarcocystis rangi frå skjelettmuskulaturen hos rein.

Abstract in Norwegian / Samandrag: Muskelcyster av S. rangi frå rein vart undersøkt ved transmisjonselektronmikroskopi. Dei lange cystene låg intracellulært i skjelettmuskelceller, og var avgrensa av ein elementærmembran, cystemembranen. Cystene var utstyrt med talrike hårliknande overflateprosessar, som strekte seg langsetter cysteoverflata. Prcsessane var opptil 12.6 Hm lange, og målte 0.3 til 0.6 \lm i diameter. Prosessane hadde ei glatt overflate, medan cystemembranen danna talrike regelmessige ordna, små invaginasjonar innimellom basis av prosessane. Cystemembranen var forsterka på innsida av eit tunnt lag av elektrontett materiale, med unnatak av dei stadene der han var invaginert. Cystegrunnsubstans danna eit lag perifert i cystene, fylte det indre av prosessane, og danna septa som delte cystene inn i talrike kammer. Dei fleste kammera inneheldt cystozoitar, medan metrocytar fannst i nokre få, små kammer perifert i cystene. Nokre av cystozoitane gjennomgjekk ei todeling ved endodyogeni. Mange metrocytar hadde eit vakuolisert cytoplasma. Cystene til S. rangi var svært like cystene til visse Sarcocystis-3.net frå andre mellomvertar med omsyn til overflatemorfologi.