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

Abstract

Summary: 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.Key words: Sarcocystis, S. rangi, reindeer, Rangifer tarandus tarandus, sarcocyst morphology, ultrastructure, transmission electron microscopy.

SCANNING ELECTRON MICROSCOPY OF THE SARCOCYSTS OF SIX SPECIES OF SARCOCYSTIS FROM REINDEER (RANGIFER TARANDUS TARANDUS)

“…However, by SEM the processes could be seen to be more numerous and more orderly distributed over the cyst surface than the TEM images would suggest. Moreover, SEM clearly showed that the cyst processes of S. rungi differed markedly in configuration from those of S. grueneri, as emphasized previously (9). However, it is evident that the cysts of S. rangi are very similar in surface morphology to the cysts of S. cruzi (syn.…”

“…The hair-like configuration of the cyst surface processes of S. rangi was also evident by TEM, as was the hexagonal packing of the minute invaginations of the cyst surface between the bases of the projections (9). However, by SEM the processes could be seen to be more numerous and more orderly distributed over the cyst surface than the TEM images would suggest.…”

“…Previous light microscopic studies of sarcocysts isolated from the musculature of Norwegian reindeer (Rangfer turundus tarandus) have revealed that six morphologically distinct types of mature sarcocysts, representing six Sarcocystis species, occur in this host (3). More recently, transmission electron microscopic studies of the cysts of these species have revealed further species-dependent morphological differences between the cysts, especially as regards the structure of the cyst wall and the related cyst surface morphology (4, 5, 6,7,8,9). However, the three-dimensional configuration, the distribution, and the relative number of some of the cyst surface specializations were difficult to infer from their appearance in ultrathin sections viewed with the transmission electron microscope.…”

Sarcocystis in moose (Alces alces): molecular identification and phylogeny of six Sarcocystis species in moose, and a morphological description of three new species

“…Colwell and Mahrt (1983) complemented the species description and assigned the name S. alceslatrans to the type A cysts that they previously had described grossly and by TEM (Colwell and Mahrt 1981). Transmission electron micrographs presented in their paper from 1981 reveal that these cysts have hairlike protrusions running along the surface of the cysts, similar to those of S. rangi of reindeer (Gjerde 1985d), Sarcocystis sybillensis of elk/wapiti (Dubey et al 1983) and…”

Sarcocystis gracilis ‐like sarcocysts in a sheep

“…Usually, Sarcocystis species are specific for their intermediate hosts; however, the occurrence of unusual Sarcocystis species in ruminants has been reported (Böttner 1984, Gjerde 1985, Novak and others 1987, Odening and others 1996. To the authors' knowledge, this is the first report of S gracilis-like sarcocysts in sheep, and this might be attributed to adaptation by the parasite to a new intermediate host during the extinction of its natural intermediate host on Sicily.…”