共查询到20条相似文献,搜索用时 15 毫秒
1.
FREDERICK C. COLLEY 《The Journal of eukaryotic microbiology》1967,14(2):217-220
SYNOPSIS. An electron microscope study of sporozoites of Eimeria nieschulzi Dieben, 1924 revealed that they have a pellicle which is thickened at the anterior end to form 2 polar rings. Radiating posteriorly from the rings, directly beneath the pellicle, are approximately 25 microtubules which may aid in support and locomotion of the sporozoite. Within the polar ring is a dense conoid. Numerous toxonemes extend posteriorly from the area of the conoid. Two paranuclear bodies are present and some toxonemes are closely associated with the anterior body. Numerous ribosomes, bodies containing granular material, and osmiophilic vesicle bounded bodies are also present. Each sporozoite has a single nucleus with a diffuse karyosome and distinct nuclear double membrane. 相似文献
2.
FREDERICK C. COLLEY 《The Journal of eukaryotic microbiology》1967,14(4):663-674
SYNOPSIS. An electron microscope study of microgametocytes and macrogametes of Eimeria nieschulzi Dieben, 1924 revealed that they lie within vacuoles bounded by a host unit membrane. The vacuole surrounding the microgametocyte contains granular material. The vacuole around the macrogamete is narrower and contains vesicles and membranes. Micropores were seen on the surface of the plasma membrane of microgametocytes and macrogametes. Microtubules were seen in macrogametes. Young microgametocytes and macrogametes have a similar cytoplasmic matrix, mitochondria and nuclei. Glycogen granules apparently develop around vacuoles in both microgametocytes and macrogametes. Glycogen granules were also seen along the margins of parallel bundles of fibers in microgametocytes. As nuclei of the microgametocyte divide, they move to the periphery of the parasite. Three basal bodies, each with 9 fibers in triplet form, develop in association with each nucleus. Microgametes have 2 free flagella and a central short, attached flagellum. Basal granules lie along the outer fibers of the central flagellum. Each microgamete has an elongate mitochondrion in close contact with the nucleus. In macrogametes wall-forming bodies develop in lacunae in the cytoplasm. Smaller dark bodies with areas of low density were also seen. Wall-forming bodies and dark bodies move to the periphery of mature macrogametes. 相似文献
3.
ALAN A. MARCHIONDO DONALD W. DUSZYNSKI CLARENCE A. SPEER † 《The Journal of eukaryotic microbiology》1978,25(4):434-437
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. 相似文献
The sporocyst wall is thin, consisting of 3 to 4 unit membranes, and measures 27 (18–34) nm thick. 相似文献
4.
5.
6.
PHYLLIS CLARKE BRADBURY BETTY B. GALLUCCI 《The Journal of eukaryotic microbiology》1971,18(4):679-686
SYNOPSIS. The first sign of merozoite formation in schizonts of Haemoproteus columbae is the accumulation of dense material at intervals beneath the plasma membrane of the schizont. The schizont's membrane then invaginates in deep furrows cleaving the parasite into pseudo-cytomeres. thereby increasing the area of membrane available for differentiation. Signs of differentiation appear under this membrane as soon as it is formed. Rhoptries and polar rings develop in the region of the dense accumulations, the cytoplasm containing these structures begins to elevate, and each evagination differentiates into a merozoite. When the merozoite is half-formed, the cytostome appears, then dense bodies at the apex of the organism, and finally a spherical body intimately associated with a mitochondrion. These merozoites of Haemoproteus are assumed to be the forms that penetrate erythrocytes and become gametocytes. They contain the same organelles as merozoites of Plasmodium. However, the merozoites of Haemoproteus are oval like the erythrocytic merozoites of Plasmodium rather than elongate like the exoerythrocytic merozoites. This body shape may be a generic characteristic or it may indicate a structural difference between exoerythrocytic merozoites and merozoites that infect erythrocytes. When the merozoites of Plasmodium, Haemoproteus and Leucocytozoon are compared, the first 2 genera appear closely related, but Leucocytozoon seems very different. Perhaps it should not be included within the Haemoproteidae. 相似文献
7.
SYNOPSIS Schizogony of Sarcocystis cruzi Hasselmann (syn. S. fusiformis Railliet) takes place in vascular endothelial cells 26 to 33 days after cattle ingest sporocysts from dogs. Kidney cortex from a heavily infected, dexamethasone-treated bovine was fixed for electron microscopy to determine the method of schizogonie development. Schizogony takes place by endopolygeny characterized by marked enlargement of the parasite nucleus, formation of nuclear lobes, presence of numerous spindles with adjacent pairs of centrioles along the nucleus, and simultaneous formation of daughter merozoites in the cytoplasm adjacent to the spindle poles. Endopolygeny in S. cruzi differs from that in other Sporozoa in that merozoite anlagen are seen in the cytoplasm before any nuclei divide. The resultant merozoites continue development and, when mature, resemble other sporozoan zoites. Upon release from the host cell into capillaries, they travel to muscle tissue to continue the life cycle by forming sarcocysts. 相似文献
8.
DATUS M. HAMMOND JOHN V. ERNST MERTHYR L. MINER 《The Journal of eukaryotic microbiology》1966,13(4):559-564
SYNOPSIS. In young first generation schizonts of E. bovis, the nuclei appeared to have a random distribution. In calves killed 8 days after inoculation some of the schizonts had the nuclei arranged in a single layer at the periphery, with a few infoldings of this layer into the interior. In further development, such ingrowths of the nuclear layer resulted in the formation of compartments of varying size. In schizonts of calves killed 12 days after inoculation spherical or ellipsoidal bodies (blastophores), about 5–20 μ in diameter with a single peripheral layer of nuclei were formed. Merozoites developed as radial outgrowths from the blastophores, leaving residual bodies of variable size, which later disappeared. The response of the host cell to the presence of the schizont was characterized by marked growth of both the nucleus and cytoplasm. The nucleolus became greatly enlarged, and the chromatin was distributed in relatively fine granules. In the host cell cytoplasm, 2 concentric layers were observed; the inner was more dense than the outer. After growth of the schizont was completed its host cell was stretched into a thin covering layer about 1 μ thick. In some schizonts, the host cell disintegrated, and the schizont was then invaded by eosinophils, macrophages and other cells, which eventually destroyed the merozoites. 相似文献
9.
SYNOPSIS. The schizonts of Haemoproteus columbae resemble the exoerythrocytic schizonts of avian Plasmodium in their fine structure. Haemoproteus infects endothelial cells and grows several hundredfold in volume, destroying the cytoplasm and nucleus of the host cell. The schizont's plasma membrane is trilamellar with a dense outer lamella. Some schizonts have micropores in their plasma membranes, but there is no evidence for ingestion thru them. Instead, numerous vesicles and channels fill the host cell cytoplasm and give its plasma membrane and periparasitic vacuolar membrane the appearance of active pinocytosis. The parasite's membrane shows no sign of pinocytosis, indicating that it probably feeds by diffusion. The growing schizont has numerous mitochondria, nuclei, and ribosome-rich cytoplasm which contains electron-lucent vacuoles and clefts. The latter appear to be artifacts of fixation. 相似文献
10.
THOMAS VARGHESE† 《The Journal of eukaryotic microbiology》1975,22(1):66-71
SYNOPSIS. The fine structure of the 1st generation merozoites of Eimeria labbeana from the ileal mucosa of artificially infected pigeons ( Columba livia ) was investigated and described. The 1st generation merozoites which appeared between 36-48 hr after infection averaged 4.4 × 2.1 μm in size. The 3-membraned pellicle was irregular in texture and harbored a single micropore, and many micropore-like invaginations. Closely apposed to the inner pellicular membrane were seen 22 microtubules, each 22–25 nm in diameter. An apical vesicle, 50 nm in diameter, seen at the anterior extremity, was connected with the common duct of the micronemes. The conoid consisted of 9 spiral elements, each 30 × 25 nm. The paired organelle (rhoptries) varied in length (1.4–2.2 μm), and the ductules (23 nm diameter) were composed of 2 inner tubules, each 6 nm in diameter. A unit membrane enveloped the partially alveolar and differentially osmiophilic interior of the bulbous regions of the rhoptries. The "rod-like structure"was found to be tubular and represented the common duct of the micronemes. 相似文献
11.
DONALD W. DUSZYNSKI SHIRLEY A. ROY GILBERT A. CASTRO 《The Journal of eukaryotic microbiology》1978,25(2):226-231
SYNOPSIS Experiments were designed to study intestinal pathophysiologic changes associated with coccidial infections in mammalian hosts. Pairs of male Sprague-Dawley rats were killed at various times postinoculation (PI) with 104 or 106 sporulated occysts of Eimeria nieschulzi. The small intestine from each rat was removed, weighed, measured, and divided into thirds. From the middle 11 cm of each third, one cm was fixed for histologic examination. Mucosa was scraped from the remaining 10 cm and was assayed for protein content and for peroxidase, sucrase and trehalase activities. Infection with E. nieschulzi was associated with increased mass of the small bowel. Histologically, crypt depth throughout the small bowel was significantly greater (P≤ 0.005) in infected rats than in non-infected ones on PI days 8 and 16. Villus height did not change drastically during low-dose infections (104 oocysts) and varied during high-dose infections (106 oocysts). As a result of these morphologic changes in the mucosa, crypt/villus ratios were usually significantly greater (P≤ 0.005) in all infected rats throughout the small bowel. In general, increased gut weight and changes in crypt and villus dimensions became evident by PI day 2, were most pronounced at PI day 8, and began to return to control values by PI day 16. Peroxidase, sucrase, and trehalase levels equaled or were slightly higher than in controls on PI day 2, dropped significantly below controls (P≤ 0.05) by PI day 8, and returned to, or exceeded control levels by PI day 16. The intensity of all changes was directly dose-dependent. 相似文献
12.
13.
SYNOPSIS. Rats inoculated with 10,000 sporulated oocysts of Eimeria nieschulzi had significantly higher total leukocyte counts on postinoculation days (PI) 1, 5, 6 and 7 when compared to control rats. Relative and absolute neutrophil counts increased concomitantly with a decrease in the relative lymphocyte levels in E. nieschulzi-infected rats on PI day 7. Absolute and relative neutrophil counts in infected rats on PI days 7 and 8 were closely correlated with the host's total oocyst discharge. The E. nieschulzi infection had no significant effect on the relative or absolute levels of monocytes or eosinophils. The described changes in leukocyte levels were not paralleled by a significant change in the erythrocyte count. 相似文献
14.
The issue of extraintestinal infection by Eimeria nieschulzi in the rat was addressed by transferring various tissues from infected to uninfected rats by mouth. All 6 rats receiving liver, spleen, or small intestine from rats killed at 3 or 8 hr postinoculation (PI), and all 5 rats receiving spleen and small intestine from rats killed 8 days PI, showed infections. Rats receiving tissues from rats killed at 8 days PI showed infections 24 hr later, indicating that fourth-generation merozoites were transferred. This is the first demonstration of an extraintestinal rodent eimerian. 相似文献
15.
SYNOPSIS. Stages of merogony of Eimeria magna were observed with the electron microscope in schizonts in ultrathin intestinal sections from white rabbits killed 4 days after inoculation. Some of the mature schizonts observed had uninucleate merozoites, whereas others had multinucleate ones. In each of the latter were rough endoplasmic reticulum, mitochondria, micronemes, refractile bodies, and occasionally, lipid droplets; some nuclei had a nucleolus. In the interior of some multinucleate merozoites, anlagen of daughter merozoites were observed. Each anlage was associated closely with a nucleus. In some of these nuclei, a cone-shaped pole of a spindle was directed toward the anlage. Each early anlage consisted of an inner membrane complex with a rhoptry anlage. A Golgi complex frequently was seen at the base of the anlage. One multinucleate merozoite, still attached to the residual body, had a merozoite anlage. In later stages of merogony, the anlagen were longer and each had a conoid. In one such merozoite, 2 merozoite anlagen were observed in close association with an eccentric intranuclear spindle, and 1 anlage had a Golgi adjunct. Another merozoite had an eccentric spindle and associated centrioles, but no visible anlagen. The finding of stages of merogony in multinucleate merozoites of E. magna indicates that these might represent a further schizogonic generation occurring in the original parasitophorous vacuole. 相似文献
16.
17.
18.
Liquid scintillation spectrophotometry was employed to determine absorption of 3H-glucose by rats infected with the coccidium Eimeria nieschulzi. In vivo studies showed increased uptake of label into small intestinal tissue and hepatic portal plasma at 3 days postinoculation and decreased absorption at 8 days postinfection compared to uninfected control animals. Observations of tissues incubated in labeled glucose in vitro confirm in vivo findings of increased uptake early in infection and malabsorption coinciding with the observation of clinical disease symptoms. 相似文献
19.
The secretory organelles of Plasmodium knowlesi were studied ultrastructurally to examine their mode of action during invasion. The formation of lamellar structures in merozoite rhoptries within late stage schizonts is prevented by the protease inhibitors chymostatin and leupeptin. Under normal conditions vesicles lined by 6-nm membranes are formed in rhoptries during erythrocyte invasion. Stereoscopic viewing of tilted sections shows that where the merozoite apex contacts the parasitophorous vacuole (PV) membrane during invasion, a domed elevation of the PV surface lies within the mouth of the rhoptry duct in contact with the secretory matrix. The membrane of the early invasion pit is thinner (6 nm) than the red cell membrane elsewhere, and sheets of lamellar material are frequently present on the invasion pit surface. These findings support the proposal that the rhoptry-microneme complex is capable of generating membranous material and inserting it into the red cell surface in a controlled manner to create the parasitophorous vacuole. On the basis of this model, measurements from serial sections show that the rhoptries could provide enough material to create a membrane lining the parasitophorous vacuole, and, with the contribution of the microspheres, could double it to accommodate the early ring stage of the parasite. 相似文献
20.
Eosinophil responses in extraintestinal and intestinal tissues were examined in August and Sprague-Dawley rats infected with Nippostrongylus brasiliensis or Eimeria nieschulzi (or both), and in uninfected controls to test the hypothesis that E. nieschulzi suppresses the systemic N. brasiliensis-induced eosinophil response. Caudal vein blood, femoral bone marrow, bronchoalveolar lavage fluid, peritoneal lavage fluid, and duodenal and jejunal samples were collected on day 8 postinfection (PI) with E. nieschulzi, on day 16 PI of the N. brasiliensis infection, when these days coincided in the concurrently infected rats, and from uninfected controls. Differential white blood cell counts were made from blood smears and cytocentrifuged preparations, and duodenal and jejunal eosinophils per villus crypt unit were quantified. Eimeria nieschulzi significantly reduced N. brasiliensis-induced eosinophil levels in peripheral blood, lavage fluids, and duodenal and jejunal tissues in both rat strains. August and Sprague-Dawley rats monospecifically infected with N. brasiliensis and concurrently with both parasites demonstrated elevated eosinopoiesis compared with uninfected controls and rats infected with only E. nieschulzi; however, despite this, concurrently infected rats had a significantly greater level of eosinopoiesis than those infected with only the nematode. In addition, E. nieschulzi induced elevated neutrophil levels in both monospecifically and concurrently infected rats in all extraintestinal tissues examined in both rat strains, whereas lymphocyte counts decreased concomitantly. This study suggests that the intestinal coccidian E. nieschulzi has the ability to modulate the systemic inflammatory response to N. brasiliensis and that this is not a rat strain-specific phenomenon. 相似文献