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Notes: Monoclonal IgG antibodies against sporozoites of Eimeria tenella were obtained from the ascites fluid of BALB/c mice. Oocysts, sporocysts, and sporozoites were exposed to medium 199, normal ascites fluid, or monoclonal antibodies 1A, 9D, 3D3II, or 2G8f. Specimens were then incubated with ferritin-conjugated goat anti-mouse IgG antibody. Ferritin was uniformly distributed over the surface of sporozoites exposed to 1A, 9D, or 3D3II; ferritin was localized in patches on sporozoites exposed to 2G8f. A uniform layer of ferritin was present on the inner layer of oocyst walls and on the Stieda body and outer surface of sporocysts exposed to 1A, 9D or 3D3II. In specimens treated with 2G8f, ferritin was present on the inner layer of the oocyst wall and the Stieda body, but not on the sporocyst wall. No ferritin was found on specimens exposed to medium 199 or normal ascites fluid. Monoclonal antibodies 1A, 9D, and 3D3II, but not 2G8f, caused complement-mediated lysis of sporozoites. These findings indicate that oocysts, sporocysts, and sporozoites of E. tenella contain common antigens specific for each monoclonal antibody tested.

Notes: SYNOPSIS. The fine-structural aspects of development of microgamonts of Eimeria magna were studied in kidney cell cultures and in experimentally infected rabbits. Spheroidal masses of gamont-like cytoplasm containing ribosomes, polyribosomes, and amylopectin granules were found within the parasitophorous vacuole; these bodies were apparently pinched off the surface of the gamont. Nucleoli were present in the early stages of nuclear division but disappeared as development proceeded. Spindles were eccentric and the nuclear membrane always remained intact in dividing nuclei. Nuclei eventually became elongate in shape, compact, and electron dense at the end oriented toward the periphery and lucent centrally. Usually, only the dense portion was incorporated into the gamete as the gamete developed by protruding from the gamont surface. Fullyformed microgametes were biflagellate and contained a nucleus, a mitochondrion, and 8-10 microtubules. Multiple-membrane complexes, which apparently originated from the nuclear envelope or endoplasmic reticulum, were found within the gamont residual body. Occasionally, 2 or 3 micro- and/or macrogamonts were seen within the same cell. In some cells one or 2 micro- or macrogamonts as well as several merozoites were present in the same parasitophorous vacuole.

Notes: The interaction of Eimeria falciformis sporozoites with the intestinal epithelium and with the intestinal contents from the cecum and colon of normal and specifically immunized mice was studied by light (LM) and scanning electron (SEM) microscopy. Fecal (FM) and enterocyte-associated (EAM) mucus were removed from the cecum and colon of normal mice and mice that had been immunized 1, 6, 12, or 20 days earlier with a series of oral inoculations of E. falciformis oocysts. Sporozoite-specific IgA, but neither IgM nor IgG, was detected by the immunofluorescent antibody test in FM and EAM from immunized mice. No sporozoite-specific immunoglobulin was detected in normal mice. When examined by LM, sporozoites exposed to all FM and EAM preparations exhibited greater motility and excystation from sporocysts. At 4 h after incubation in FM or EAM from normal or immune mice, about 10% of the sporozoites appeared damaged, being non-motile and non-refractile. Immune FM and EAM caused agglutination of sporozoites and sporocysts and oocyst walls of E. falciformis. but did not agglutinate those of E. ferrisi. Scanning electron microscopy of in vitro interactions between E. falciformis sporozoites and intestinal contents revealed that sporozoites exposed to immune EAM were coated with particulate material whereas those exposed to normal EAM were relatively clean. Sporozoites exposed to immune FM were usually embedded within the mucus whereas those exposed to normal FM were situated on top of the mucus. No significant differences occurred between the length/width (L/W) ratios of sporozoites incubated in normal FM and EAM or in PBS. Sporozoites exposed to immune FM had significantly greater L/W ratios than those exposed to normal FM whereas those exposed to immune EAM had significantly shorter L/W ratios than ones exposed to normal EAM. Few of the sporozoites observed on the luminal surface of the colon and cecum of normal mice were covered by mucus and none was altered in shape or showed pellicular damage. Only a few sporozoites were observed on the luminal surface of the colon and cecum of immunized mice. Most of these were covered by mucus and some exhibited pellicular alterations.

Notes: SYNOPSIS. The development of Sarcocystis cruzi Hasselmann (syn. S. fusiformis Railliet) meronts was studied in seven 7- to 10-day-old calves killed 4, 7, 11, 15, 22, 25 and 28 days postinoculation (DPI) with 5 × 107 sporocysts from feces of coyotes. No meronts were found 4 and 7 DPI. Young and intermediate meronts with 1–16 nuclei were found in endothelial cells of arteries in mesenteric lymph nodes, but not in kidneys 11 DPI.Mature meronts were noted in endothelial cells of arteries, arterioles, or capillaries of many organs of calves killed 15 to 25 DPI. No first-generation meronts were found 28 DPI. By electron microscopy, all stages of the first-generation merogony were found free within the host cell cytoplasm and not within a parasitophorous vacuole. The appearance of intranuclear spindles preceded the formation of merozoites by endopolygeny. Mature meronts measured 41.0 × 17.5 (34–50 × 15–24) μm, contained ∼ 100–350 merozoites, and had 2 to 4 relatively small residual bodies, 2.8 μm in diameter. Merozoites measured 6.3 × 1.5 (5.5–7 × 1 μm) and contained most of the organelles characteristically found in coccidian merozoites. Micropores were observed in merozoites, but not in young and intermediate meronts. Merozoites were seen free in the lumen of blood vessels, in intracellular areas, and free within the host cell cytoplasm.

Notes: Synopsis. Hammondia pardals sp. n. (Eimeriorina: Sarcocystidae) from Panama Canal Zone is described as an obligate heteroxenous coccidian, with felids as the final host and laboratory mice as the experimental intermediate host. Ovoid oocysts. measuring 40.8 (36–46) × 28.5 (25–35) m̈m. are shed unsporulated. Oocysts were infective only for the intermediate host. the laboratory mouse, Mus musculus, and the intracellular cysts were infective only for felids. Attempted passage of tissue cysts from mouse to mouse was unsuccessful.Mice fed 5 × 104 sporulated oocysts were found to harbor small intracellular cysts, 13–16 × 10–15 m̈m, in the mesenteric lymph nodes, lungs, and intestinal submucosa 15 days postinfection. The meronts in these early cysts were stubby and measured 3 × 6 m̈m. The prepatent period in the felids was 5 to 8 days and the patent period 5–13 days. Experimental infections of definitive hosts were successful with 6/6 domestic laboratory-reared kittens, Felis catus; 5/5 ocelots, F. pardalis; and 1/1 jaguarundi, F. yagouaroundi. None of the exposed raccoons, Procyon lotor, shed oocysts.

Notes: SYNOPSIS. Oocysts of Eimeria nieschulzi from the laboratory rat, Rattus, norvegicus, were studied by scanning and transmission electron microscopy. Oocysts had a rough outer wall with apparent random depressions. The oocyst wall is composed of 2 layers: an osmiophilic outer layer consisting of a rough external and smooth internal surface, and a relatively thick, electron-lucent inner layer. The outer layer is composed of a dense, coarsely granular matrix. The inner layer consists of homogeneous fine granular material interspersed with coarse osmiophilic granules and contains one closely applied membrane on the outermost surface. Several raised lenticular areas are seen on the coarse outer surface of the inner layer. These layers are 102 (75–128) and 176 (135–204) nm thick, respectively.The sporocyst wall is thin, consisting of 3 to 4 unit membranes, and measures 27 (18–34) nm thick.

Notes: SYNOPSIS. Material from various steps obtained in the French pressure cell technic of preparing antigen from Plasmodium knowlesi-infected red cells, was examined by electron microscopy. A positively charged colloidal iron solution was used to differentiate between membranes of host red cells and parasites. Red cell membranes take the stain, whereas parasite membranes do not. This antigen which has been used previously to protect monkeys against P. knowlesi appears to consist almost entirely of membrane-bounded vesicles. Some of these vesicles contain a fine granular material, whereas others appear empty. The antigen failed to stain with the positively charged iron solution, which suggests that it is free of contamination by host cell membrane.

Notes: SYNOPSIS. Oocysts of Isospora serini and Isospora canaria, from the canary Serinus canarius, were broken, added to a cell suspension, fixed in Karnovsky's fluid, and studied in the electron microscope. The oocyst wall of each species had an electronlucent inner layer, a more osmiophilic middle layer and an outer layer of electron-lucent (I. serini) or electron-dense material interspersed with some electron-lucent material (I. canaria). A few, relatively large lipid-like bodies were present in the outer or middle layer of the oocyst wall of I. canaria. As many as 9 membranes were present in the oocyst wall of I. canaria and 3 in that of I. serini. When exposed to a trypsin-sodium taurocholate fluid, sporozoites of I. serini excysted from 5-month-old sporocysts in vitro, but not from sporocysts stored for more than 6 months. No excystation occurred in 15-month-old I. canaria sporocysts. Similarities and differences in excystation between I. serini and other Isospora, Eimeria, and Sarcocystis species are discussed.

Notes: . Sporocysts of the coccidian Sarcocystis tenella were originally isolated in the feces of a coyote. Sporocysts used for inoculation of lambs were obtained from experimentally infected dogs. At 14, 16, and 19 days postinoculation (DPI) of lambs with the sporocysts, various developmental stages of first-generation meronts were found within cells located between the endothelium and internal elastic membrane of mesenteric arteries. At 19, 21, and 25 DPI, second-generation merogony occurred in cells associated with capillaries and arterioles of kidney glomeruli and convoluted tubules. Meronts of both generations were bounded by a double pellicular membrane and were situated free in the host cell cytoplasm. Merozoites formed by endopolygeny that involved multiple intranuclear spindles of a single, large irregular nucleus. First-generation meronts measured 22.6 × 17.1 μm (19–28.7 × 7.5–24 μm) and contained 120–240 merozoites, which measured 7.1 × 1.6 μm (4.8–7.5 × 1.3–1.8 μm). Corresponding values for second-generation meronts were 13.2 × 9.2 μm (8.3–15 × 7–13.5 μ), 32–80, and 5.8 × 1.7 μm (5.6–6.2 × 1.4–2.2 μm).

Notes: SYNOPSIS. Mature macrogamonts were present in the small intestine of rats 5.5 to 7.5 days postinoculation with Eimeria nieschulzi oocysts; oocysts were present at 6 to 7.5 days. Types I and II wall-forming bodies in macrogamonts began to undergo ultrastructural changes within zygotes to form the outer and inner layers of the oocyst wall. Before and during oocyst wall formation a total of 5 membranes (M1–5) were formed at or near the surface of the zygote. The outer and inner oocyst wall layers formed between M2 and M3, and M4 and M5, respectively. The mature oocyst was loosely surrounded by M1 and M2, had an electron-dense outer layer, 100–275 nm thick, and an electron-lucent inner layer, 160–180 nm thick. It also contained an electron-lucent line consisting of M3 and M4 interposed between the outer and inner layers of the oocyst wall. The micropyle, measuring 935 × 47 nm, was located in the outer layer of the oocyst wall and consisted of 10–14 alternating layers of electron-dense and lucent material. The sporont of mature oocysts was covered by M5, immediately beneath which were M6 and M7. The sporont contained a nucleus and nucleolus, lipid and amylopectin bodies, mitochondria, ribosomes, as well as smooth and rough endoplasmic reticulum. Canaliculi, Golgi complexes, and types I and II wall-forming bodies were absent.