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Notes: A Tritrichomonas foetus-likt flagellate was found in the stomach, small intestine, and cecum as well as in the nasal cavity of pigs. Xo appreciable differences in morphology or response to cultivation could be found among the trichomonads from the different sites; therefore, it is considered that they.belong to a single species, Tritrichomonas suis (Gruby & Delafond). a description of which is given. This organism could be grown indefinitely in various media, and, after a short period of cultivation, it was the only species surviving in cultures that originated from cecal samples containing 2 or 3 species. T. suis was found in the nasal cavity in 55 of 100 pigs, in the stomach in 41 (8.0%) of 512, in the small intestine in 3 of 100. and in the cecum in 215 (43.370) of 496. A T. batrachorum-type trichomonad, herein described as Tritrichomonas rotunda n. sp., was found in the cecum in 52 (10.5%) of 496 pigs. This species is typically broadly pyriform or rotund (average length 8.95 ± 0.83 ii, range, 6.83-11.4), with 3 equal or subequal anterior flagella slightly longer than the body, a relatively low undulating membrane extending y2 to 2/1 of the length of the body, and a posterior free flagellum usually a little shorter than the body. The narrow axostyle, expanded anteriorly into a curved capitulum closely associated with the large, spherical, anteriorly located nucleus, projects from the posterior surface of the flagellate for a distance which equals about 2/3 half of the body length. The parabasal apparatus is biramus. This species could be maintained only temporarily in media not containing extracts of cecal contents. A Trichomonas pronazeki-typt flagellate, found in the cecum in 126 (25.4%) of 496 pigs and in the small intestine in 1 of 100. is described as Trichomonas buttreyi n. sp. This organism is relatively small (average length 5.92 ± 0.79 μ, range 4.55-7.49). ellipsoidal in shape, with 5 to 4 flagella up to twice as long as the body, a relatively high undulating membrane of body length, a narrow axostyle with an inconspicuous capitulum closely associated with the usually oval nucleus, a projecting part of the axostyle that equals about j; of the body length, and a disc-shaped parabasal body lying dorso-lateral to the nucleus. In media without cecal extract this species could not be subcultured.

Notes: SYNOPSIS. Monolayers of bovine kidney cells were overlaid with Eimeria magna sporozoites and observed with phase-contrast optics until penetration of the cells by the parasites had begun. Cells and penetrating parasites were fixed with glutaraldehyde and OsO4-containing ruthenium red, dehydrated, and embedded in situ. Cells being penetrated were selected for study in the electron microscope. The lack of intracellular staining with ruthenium red and intact plasmalemmas of cells being penetrated, was accepted as evidence that the sporozoites did not disrupt the plasma membranes. The sporozoite caused invagination of the host cell plasmalemma until the parasite was entirely within the cell, after which the invagination was sealed off by short pseudopodia enclosing the sporozoite within a membrane-lined vacuole inside the cell. Often myelin-forms, apparently of host cell origin, were seen in the space between the sporozoite and the cell.

Notes: SYNOPSIS. Macrogamonts in tissues from rabbits killed 5 1/2 days after inoculation with Eimeria magna oocysts were studied with the electron microscope. In young macrogamonts, parts of cytoplasm, sometimes including micronemes, were pinched off into the parasitophorous vacuole. In all stages of development, small segments of the inner membrane complex were present beneath the limiting membrane. Micropores also were seen in all stages, and some apparently functional ones were present in mature macrogametes. Wall-forming bodies of Type I and Type II were observed in relatively early stages. The former were less numerous than the latter, which had a more compact appearance than in other species. Usually, several Golgi complexes were present and several Golgi adjuncts occurred in the vicinity of the nucleus in all stages of development. Microgametes were observed in the cytoplasm of host cells harboring immature macrogametes.

Notes: SYNOPSIS. In vitro development of Eimeria canadensis from cattle was studied in monolayer cultures of various bovine cell lines grown on coverslips in Leighton tubes. Excysted sporozoites were used for inoculation of the cell cultures. Sporozoites entered the host cells within a few minutes, but apart from a reduction in the number of refractile bodies, changed little in appearance during the first 9 days. Beginning at 91/2 days postinoculation, sporozoites developed into sporozoite-shaped schizonts or, less frequently, transformed into trophozoites. Sporozoite-shaped schizonts with as many as 8 nuclei were observed transforming into spheroid schizonts. At 111/2 days, intermediate schizonts had a characteristic single mass of refractile granules and 60–80 nuclei. Deep invaginations, which resulted in the formation of several blastophores, usually occurred when schizonts had about 100 nuclei. Merozoites were formed as a result of radial outgrowth from the surface of spheroid schizonts as well as of blastophores. Mature merozoites were seen 1st after 13 days.

Notes: SYNOPSIS. Cell lines of embryonic lamb trachea (LETr), lamb thyroid (LETh), and bovine liver (BEL) as well as an established cell line of Madin-Darby bovine kidney (MDBK) were used in a study of the in vitro development of Eimeria crandallis from sheep. Excysted sporozoites were inoculated into Leighton tubes containing coverslips with monolayers of the different cell types. Coverslips were examined with phase-contrast and interference-contrast at various intervals up to 20 days after inoculation; thereafter the monolayers were fixed and stained in various ways. Freshly excysted sporozoites, with 2–10 spheroidal refractile bodies, entered all of the cell types in relatively small numbers; intracellular sporozoites were first seen 2 min after inoculation. After 24 hr, most intracellular sporozoites had only 1 or 2 refractile bodies. Before and during transformation of sporozoites, the nucleus and peripheral nucleolus increased markedly in size. Transformation resulted in usually spheroid but sometimes ellipsoid trophozoites. Trophozoites were seen first 3–4 days, and binucleate schizonts at 4–5 days after inoculation. Immature schizonts increased considerably in size and eventually had large numbers of nuclei. Some of the parasites became lobulated and the lobules often separated to form individual schizonts. In BEL, LETr and LETh cells, mature schizonts, up to 150 μm in diameter, were seen first 11–14 days after inoculation. The BEL cells were the most favorable for development. Merozoites were formed by a budding process from the surface of the schizonts as well as from blastophores. Some merozoites were seen leaving mature schizonts, but no further development was observed. Merozoites frequently were motile and had a sharply bent posterior end. Marked nuclear and cytoplasmic changes were observed in parasitized cells.

Notes: SYNOPSIS. Monolayer cell line cultures of ovine trachea, thyroid, thymus, and kidney cells, as well as an established cell line (Madin-Darby) of bovine kidney cells, were inoculated with sporozoites of Eimeria ninakohlyakimovae and observed for a maximum of 24 days. Sporozoites were seen penetrating cells within 5 minutes after inoculation, as well as 2 and 3 days after inoculation, and leaving cells 3 days after inoculation. Transformation from sporozoites to trophozoites occurred by a widening or by a lateral outpocketing of the sporozoite body. Trophozoites and schizonts were first seen 3 days after inoculation in all ovine cell types. Large numbers of immature schizonts were observed, but only an estimated 0.4–4.3% of these became mature in the different kinds of cells. Usually, mature schizonts were first seen 10–11 days after inoculation in the ovine cells, but they sometimes occurred as early as 8 days. More mature schizonts were seen in the ovine kidney and trachea cells than in the others; the smallest number occurred in the bovine cells. The nucleoli of cells harboring large schizonts in each type of culture were enlarged and the chromatin clumps normally seen in the nuclei of non-infected cells were not visible. The cytoplasm of some infected cells was vacuolated. The formation of merozoites occurred by a budding process from blastophores, from the surface of schizonts, and/or from infoldings and invaginations of this surface. Merozoites were observed leaving host cells, but were not seen penetrating new cells. Intracellular first-generation merozoites were observed 13 and 15 days after inoculation in lamb trachea and kidney cells, respectively. No evidence of further development of such merozoites was found.

Notes: SYNOPSIS The development of 1st generation schizonts of Eimeria callospermophili was studied with cell cultures and with experimentally infected host animals, Spermophilus armatus. Sporozoite-shaped schizonts each had 5-10 nuclei and all of the organelles of the sporozoite; each nucleus had a nucleolus and an associated Golgi apparatus. In stages immediately preceding merozoite formation, an intranuclear spindle apparatus with conical polar areas were observed near the outer margin of each nucleus. Two centrioles, each having 9 single peripheral tubules and one central tubule, were observed near each pole in some specimens. Merozoite formation began internally, with anlagen of 2 merozoites developing near each nucleus. The inner membrane of the merozoites first appeared as 2 dense thickenings adjacent to the polar cones and centrioles; subpellicular microtubules appeared simultaneously. Two anterior annuli and the conoid formed between the 2 thickenings. Vesicles, possibly of Golgi origin, were located next to the forming inner membrane. As the forming merozoites underwent elongation, a rhoptries anlage, a Golgi apparatus, refractile bodies, and mitochondria were incorporated into each. Sporozoite-shaped schizonts with merozoite anlagen transformed into spheroid or ovoid schizonts; at this time the conoid, rhoptries, micronemes, and the inner membrane of the pellicle gradually disappeared; several small refractile bodies were formed from the larger one. When development was about 1/3 complete, the immature merozoites began to grow outward from the surface of the schizont. In this phase of development, the single surface membrane of the schizont became the outer membrane of the merozoite's pellicle, and additional organelles, including the nucleus, were incorporated. Finally, the merozoites became pinched off, leaving a residual body. Development in cell cultures and host tissues was similar. This type of schizogony, previously undescribed in Eimeria, is compared with corresponding stages of development in other species of Eimeria and Sporozoa.

Notes: SYNOPSIS. Monolayer established cell line cultures of bovine kidney (Madin-Darby) and human intestine (Intestine 407), as well as embryonic bovine tracheal and embryonic spleen cell line cultures were inoculated with E. auburnensis sporozoites and observed for a maximum of 22 days. Mature 1st generation schizonts developed in the kidney, tracheal and spleen cells. In the intestine cells, trophozoites were seen in 3 of 4 experiments, but schizonts were not found. Sporozoites penetrated cells, beginning within a few minutes after inoculation. Penetration was usually accomplished within 10 seconds, and the body of the sporozoite underwent a slight constriction as it passed thru the host cell membrane. Some sporozoites left cells. Numerous intracellular sporozoites were observed in kidney, tracheal and spleen cultures. Crescent bodies were seen in the parasitophorous vacuole as early as 1 day after inoculation. At this time, the nuclei of most intracellular sporozoites had changed from vesicular to compact.Beginning 4 days after inoculation, enlarged sporozoites and parasites having a sporozoite shape, but with 2-5 nuclei, were frequently seen. These enlarged sporozoites and sporozoite-shaped schizonts evidently transformed into trophozoites and spheroidal schizonts by means of lateral outpocketings. Few trophozoites were seen. More immature schizonts developed in kidney cells than in the other cell types. The numbers of mature schizonts observed in kidney and tracheal cells were similar, but development occurred less consistently in the latter. Few immature and mature schizonts developed in spleen cells. Mature schizonts, first seen 9 days after inoculation, were considerably smaller than those reported from calves. Some motile merozoites were seen; evidently no development beyond these occurred. The nucleus and nucleolus of host cells were enlarged; this enlargement was not as pronounced as in infections in calves. Multiple host cell nuclei were frequently observed. Degenerative changes in the cultured cells and in the parasites usually occurred, beginning 9-17 days after inoculation; these were more pronounced in the spleen cells than in the others.

Notes: SYNOPSIS. Oocysts of Eimeria bilamellata were found in Spermophilus armatus, Utah and Wyoming; S. beecheyi, California; and S variegatus, Utah. Oocysts were not found in S. lateralis, S. richardsoni, S. columbianus, S. tridecemlineatus, or the white-tailed prairie dog, Cynomys leucurus. Experimental infections were established in S. armatus, S. variegatus, and S. lateralis, but not in S. richardsoni, least chipmunks Eutamius minimus, laboratory rats Rattus norvegicus, or Mongolian gerbils Meriones unguiculatus. After one experimental infection S. armatus and S. variegatus were immune to further infections. Spermophilus lateralis could be infected 3 or 4 times before the animals were immune. However, individuals of S. armatus in a natural population had more than one infection with E. bilamellata; probably infections must be of a certain level before immunity develops. When S. armatus were inoculated with about 100,000 oocysts, the animals usually died on the 7th day after incoculation.Oocysts were 33-37 by 25-31 μ (mean 34.5 by 28.2 μ). The oocyst wall was brown and composed of 2 layers. A distinct micropyle was present. Sporocysts were 18-23 by 9-12 μ (mean 19.9 by 10.3 μ). In experimental infections, the prepatent period was 10 days and the patent period 5–21 (mean 9) days. Schizonts were 1st seen 7 days after inoculation. They were located above the host cell nuclei of epithelial cells at the tips of the villi of the jejunum and ileum. One or more earlier generations of schizonts were thought to occur, but these were not observed. Gametogony took place in epithelial cells of the jejunum and ileum. Shortly after the merozoites entered the cells, the cells became enlarged and were displaced into the lamina propria. The microgametocytes were considerably larger than the macrogametes and contained a central residual body. Macrogametes had a peripheral eosinophilic layer as well as cytoplasmic granules; both apparently participated in formation of the oocyst wall.

Notes: SYNOPSIS. In the nearly mature macrogametes of Eimeria auburnensis, the cell membrane is a unit membrane, with underlying and overlying osmiophilic layers usually present. Cup-shaped micropores were occasionally seen. Smaller, V-shaped invaginations were also found in considerable numbers at the surface. At the deepest point, these invaginations were bounded only by a unit membrane. Immediately adjacent to this point, vesicles with homogenous electron-pale contents bounded by a similar unit membrane, were frequently seen. Pinocytosis evidently occurs at the site of these invaginations. Numerous folds of the host cell membrane bordering the vacuole in which the parasite lay extended about 0.1–0.7 μ into the vacuole. These “intravacuolar folds” varied in depth and number in different specimens. In some, the majority of folds had apparently become disconnected from the host cell membrane. A highly developed smooth endoplasmic reticulum occurred in the adjacent host cell cytoplasm. The intravacuolar folds may assist in transfer of nutrients, including membrane material, from the host cell to the parasite. The evidence indicates that in this species of Eimeria nutrients are taken into the parasite primarily as fluids by pinocytosis and possibly other processes.