For the comparison of surface fine structures in the proliferative forms of two major protozoan parasites, Toxoplasma gondii and Sarcocystis species in mammalian hosts, isolated from the artificially infected mice and from the naturally infected cattle, respectively, an SEM(Hitachi S-570) was applied to the fixed, dried and coated with gold ion on the microslide glasses. The tachyzoites of T. gondii from the peritoneal cavity of the mouse showed the crescent-like feature and measured as 5.57 micro m in length and 2.33 micro m in width, while the bradyzoites of Sarcocystis species from the heart muscle of slaughtered cattle was banana-shaped and measured 14.18 micro m in length and 2.85 micro m in width. On the surface of Sarcocystis species bradyzoite, a distinct elliptical micropore was identified in the high magnification observation of 60,000X, and it measured as 0.35 micro m in length and 0.18 micro m in width.

A preliminary survey of Sarcocystis species in the slaughtered cattle in Seoul was undertaken during October through December 1987, using digestion diagnostic technique for the heart muscle specimens digested in 0.5 % trypsin solution. Results indicated that 41.5 % of 159 bovine hearts were infected with Sarcocystis proliferative forms. High frequencies in the exotic dairy cattle (42.2%) and the Korean native cattle (41.7%) were noticed in comparison with low frequency in the cross breed (25.0%). No differences were indicated between the sexes of the host animals, although an age difference was noticed as 48.9 % in cattle older than four years in comparison with 39.0 % and 37.1 % in younger than two years and in two to four years, respectively

For the laboratory diagnosis of Sarcocystis infections especially in domesticated food animals, several antificial digestion techniques were applied for the musculature specimens and several staining techniques wes applied for the bradyzoites of Sarcocystis species isolated. The digestion technique using trypsin (0.5%) and sodium chloride (0.85%) mixed solution was regarded as the most valuable for the detection of asexual stages of Sarcocystis in bovine musculature specimens. Optimal time for digestion was approximately one to four hours. The trypsin digestion technique with Giemsa's stain could be helpful for the detection of Sarcocystis proliferative forms and for the observation of the nucleus of the parasite. A systematic detection was also performed in an autopsy for a bovine carcass naturally infected with Sarcocystis species, and the asexual stages such as metrocytes and bradyzoites were observed in the specific organs, respectively