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1.
Morphometric and morphological observations on C. nili in an experimentally infected fish (using the leech vector Batracobdeloides tricarinata for the first time) revealed two successive types of merogonic cycles occurring within the fish erythrocytes. In the first cycle large meronts produced eight small merozoites each while in the second cycle smaller meronts produced four merozoites each. Merozoites of the second cycle were destined to become gamonts. The gamonts were somewhat larger than merogonic stages and comprised the majority of the parasitic stages during parasitemia for up to 8 months. In the leech crop, gamonts released from the fish erythrocytes, became associated in syzygy and fused. The formed zygote underwent sporogony within the intestinal tissues and up to 60 sporozoites were produced from an ovoid or round oocyst. The produced sporozoites migrated toward the salivary and the proboscis tissues. The parasite survived in the leech over a period of 8 months involving 5 meals after the initial meal provided the fasting period did not exceed 75-105 days. Survival was attributed to residual stages in the proboscis and salivary tissues. Cross transmission experiments between fishes via B. tricarinata revealed that the fish haemogregarines were not host specific. Previously described African fresh water fish haemogregarines were indistinguishable and on the basis of the current results, they are regarded as a single species Cyrilia nili.  相似文献   

2.
Transmission electron microscopic study of endogenous development of Eimeria turcicus Upton, McAllister and Freed, 1988 (Eimeriorina, Apicomplexa), in the gall bladder epithelium of the gecko Hemidactylus turcicus from Israel, revealed merogony and gamogony stages which induce hypertrophy and displacement of their host cell from the epithelial layer. Meronts yield over 70 merozoites. Microgametes are biflagellated. Macrogamonts contain both types of wall-forming bodies (WF1, 2). In the zygote, disaggregation of WF1s coincide with the onset of oocyst wall formation, while WF2s persist. A multilayered wall is formed at the first stage of the wall formation. Subsequently, 5 membranes (M1-5) are formed at the surface of the zygote like in other elmerine coccidia. The oocyst wall appears to be formed by M3 and M4.  相似文献   

3.
The structure of the adrenal gland was studied in 11 bottlenose dolphins ( Tursiops truncatus ), and five striped dolphins ( Stenella coeruleoalba ). These species are legally protected in Croatia. All examined animals died of natural causes and were found stranded along eastern Adriatic coast. In both species the adrenal gland consists of a cortex and a medulla; the cortex is divided into three zones. Whereas in the bottlenose dolphin, there is a zona arcuata which contains columnar cells arranged in the form of arches; in the striped dolphin this zone is replaced by zona glomerulosa containing rounded clusters of polygonal cells. In both species, the zona fasciculata consists of radially oriented cords of polygonal cells, whereas in zona reticularis cells are arranged in branching and anastomosing cords. The adrenal medulla in both species contains dark, epinephrine-secreting cells and light norepinephrine-secreting cells. Epinephrine-secreting cells are localized in the outer part of the medulla, whereas norepinephrine-secreting cells are found in the inner part, arranged in clusters and surrounded by septa of thin connective tissue. The gland is surrounded by a thick connective-tissue capsule, from where thick trabeculae extend towards the interior. In the bottlenose dolphin, group of cells resembling both medullar and cortical cells can be seen within the capsule; whereas only groups of cells resembling cortical cells are found within the capsule of the striped dolphin. In the bottlenose dolphin invagination of the adrenal cortex into the medulla is obvious as well as medullary protrusions extending through cortex to the connective tissue capsule.  相似文献   

4.
Three chief cell types were studied in 8 canine mixed mammary tumors--luminal epithelial cells, myoepithelial cells, and filament cells, the last being the "stellate" cells recognized by light microscopists. Most cytoplasmic filaments in the myoepithelial cells were 5 to 8 nm thick, whereas another type of filaments were scattered, 8 to 10 nm thick. Almost all cytoplasmic filaments in the filament cells were 8 to 10 nm thick. In the adenomatous parts of the tumors, myoepithelial cells were chiefly seen, along with luminal epithelial cells. Filament cells were rarely observed without intercellular accumulation of mucoid. The filament cells were largely confined to the myxomatous and chondromatous parts of the tumors. The presence of cells of transitional forms in adenomatous areas suggested that the filament cells were derived from the myoepithelial cells.  相似文献   

5.
American canine hepatozoonosis is caused by Hepatozoon americanum, a protozoan parasite, the definitive host of which is the tick, Amblyomma maculatum. Infection of the dog follows ingestion of ticks that harbor sporulated H. americanum oocysts. Following penetration of the intestinal mucosa, sporozoites are disseminated systemically and give rise to extensive asexual multiplication in cells located predominantly in striated muscle. The parasitized canine cells in "onion skin" cysts and in granulomas situated within skeletal muscle, as well as those in peripheral blood leukocytes (PBL), were identified as macrophages by use of fine structure morphology and/or immunohistochemical reactivity with macrophage markers. Additionally, two basic morphologic forms of the parasite were observed in macrophages of granulomas and PBLs. The forms were presumptively identified as merozoites and gamonts. The presence of a "tail" in some gamonts in PBLs indicated differentiation toward microgametes. Recognition of merozoites in PBLs supports the contention that hematogenously redistributed merozoites initiate repeated asexual cycles and could explain persistence of infection for long periods in the vertebrate host. Failure to clearly demonstrate a host cell membrane defining a parasitophorous vacuole may indicate that the parasite actively penetrates the host cell membrane rather than being engulfed by the host cell, as is characteristic of some protozoans.  相似文献   

6.
A new myxosporean species, Henneguya eirasi n. sp., is described parasitizing the gill filaments of Pseudoplatystoma corruscans and Pseudoplatystoma fasciatum (Siluriformes: Pimelodidae) caught in the Patanal Wetland of the state of Mato Grosso, Brazil. The parasite formed white, elongated plasmodia measuring up to 3mm. Mature spores were ellipsoidal in the frontal view, measuring 37.1 ± 1.8 μm in total length, 12.9 ± 0.8 μm in body length, 3.4 ± 0.3 μm in width, 3.1 ± 0.1 μm in thickness and 24.6 ± 2.2 μm in the caudal process. Polar capsules were elongated and equal in size, measuring 5.4 ± 0.5 μm in length and 0.7 ± 0.1 μm in width. Polar filaments had 12-13 coils. Histopathological analysis revealed that the parasite developed in the sub-epithelial connective tissue of the gill filaments and the plasmodia were surrounded by a capsule of host connective tissue. The plasmodia caused slight compression of the adjacent tissues, but no inflammatory response was observed in the infection site. Ultrastructure analysis revealed a single plasmodial wall connected to the ectoplasmic zone through numerous pinocytotic canals. The plasmodial wall exhibited numerous projections and slightly electron-dense material was found in the ectoplasm next to the plasmodial wall, forming a line just below the wall. Partial sequencing of the 18S rDNA gene of H. eirasi n. sp. obtained from P. fasciatum resulted in a total of 1066 bp and this sequence did not match any of the Myxozoa available in the GenBank. Phylogenetic analysis revealed the Henneguya species clustering into clades following the order and family of the host fishes. H. eirasi n. sp. clustered alone in one clade, which was the basal unit for the clade composed of Henneguya species parasites of siluriform ictalurids. The prevalence of the parasite was 17.1% in both fish species examined. Parasite prevalence was not influenced by season, host sex or host size.  相似文献   

7.
The ultrastructure of the parasitophorous cyst, the metrocytes and merozoites of Sarcocystis tenella (S. ovicanis) was studied. The general ultrastructural features of the cyst wall and the cells of the protozoan, previously described by other authors, were confirmed. The vesicle-like invaginations of the unit membrane (primary wall) of the cyst are identical with the micropinocytic pits of other animal cells, and we believe that they contribute to the nutritional process of the cyst. The Golgi apparatus must be related to the granular endoplasmic reticulum, since the first cisterna of the curved side of the stack appeared to originate from it. The structure of the micropore was similar to that previously described by other workers, the only difference being that in this study, material was frequently observed inside the lumen. This observation led us to support the previously suggested nutritive role. In addition, crystalloid material limited by cytoplasmic membrane was often observed, but the manner of its formation and role remain unknown.  相似文献   

8.
史娟  王华荣  钟少林 《草业学报》2012,21(5):122-127
从细胞角度揭示苜蓿假盘菌与苜蓿叶片亲和性互作机制。以两者亲和性互作系统为研究材料,利用透射电子显微镜技术研究了苜蓿假盘菌与苜蓿叶片亲和性互作的超微结构特征。结果表明,病菌侵入寄主组织后,菌丝直接穿透寄主细胞壁进入寄主细胞形成胞内菌丝,以胞内生长并向相邻细胞扩展。病菌菌丝穿透寄主细胞壁时,菌丝中的液泡给予了较大的压力帮助其穿透。进入寄主细胞内的病菌菌丝,被内陷的寄主原生质膜包裹,菌丝与质膜始终是隔离的,寄主原生质膜和细胞壁之间沉积电子致密度深的物质。病菌菌丝不断地在寄主原生质膜区域扩展,伴随菌丝体在寄主细胞内的不断扩大,周围的原生质膜也相应扩大其面积,但始终将寄主原生质与菌丝体隔开,而脱离质膜的菌丝形成菌丝鞘包裹。随侵染程度的增加,未被穿透的寄主原生质膜区域逐步被降解。病菌侵染叶绿体等细胞器时,首先是菌丝鞘与叶绿体等细胞器膜相连,然后降解其基粒片层结构,被降解的细胞器组织沿菌丝和胞壁周围沉积。侵染后期,菌丝胞内和胞外扩展,但处在细胞降解物中的菌丝显示较厚的细胞壁,寄主细胞内充满了大量的黑色物质和结晶状的颗粒物。  相似文献   

9.
A seven‐month‐old purebred Nelore calf was diagnosed with a bilateral finger‐shaped swelling although more prominent at the left side of the scrotum, located longitudinal and parallel to epididymis corpus. The finding was present from 7 months of age up to castration (performed at 25 months of age). Scrotal circumference, testicular and epididymis consistency and symmetry as well as seminal quality were normal during the follow‐up period. The ultrasonographic appearance of the scrotal wall, pampiniform plexus, gonad and epididymis was normal. However, an anechoic region surrounded by a wall forming a sac‐like structure with a blind end at its dorsal pole was seen on the swelling area. The examination of fluid aspirated from the saccular contents revealed the presence of mononuclear cells mainly from lymphocytic and histiocytic type as well as some loosing degenerated mesothelial cells. Gross examination at castration revealed a blind sac‐like appendix derived from an evagination in the parietal layer of the tunica vaginalis. The structure of approximately 5.0 cm in length extended from the dorsal edge of the epididymis cauda. No adherences with surrounded tissues were observed. Histopathology of the sac wall showed a smooth inner surface composed by scarce mesothelial cells forming in some areas papillary‐like projections protruding to the vaginal cavity. Underneath, a thick layer of fibrous tissue mixed with collagen fibres and mononuclear inflammatory cells were seen. The potential consequences of this saccular formation at an older age in a bull are unknown.  相似文献   

10.
This study aims to assess the ability of essential oils (EOs) to destroy Eimeria oocyst in vitro using microscopic counting and 273 nm absorbing material release. A screening for the ability of ten EOs to destroy Eimeria oocyst was carried out in liquid medium. Out of these ten, artemisia, tea tree, thyme and clove EOs were identified as being the most effective. The treatment of Eimeria oocyst with these EOs leads to their lysis as shown by the release of substances absorbing at 273 nm. These results were obtained after approximately three hours contact. Four EOs were proven to destroy Eimeria oocysts in a few hours at low concentration. This destructive effect is a consequence of their lysis. This work is a preliminary contribution aiming to develop a new generation of natural efficient agents for destroying Eimeria oocyst to fight coccidiosis in broiler chicken.  相似文献   

11.
Cysts of Sarcocystis capracanis obtained from infected goats were examined to clarify the effect of the parasite on the host. Muscle tissues from fresh oesophagus, tongue, diaphragm and skeletal muscles of 680 goats were slaughtered in the main abattoir of Cairo, Egypt and they were examined microscopically for Sarcocystis infection for the first time in Egypt. 540 out of 680 (79.4%) of examined goats were found to be infected with Sarcocystis sp. The infection was recorded firstly by light microscopy as spindle shaped cysts embedded in the muscle tissues. The validity of this species as S. capracanis was confirmed by means of ultrastructural characteristics of the primary cyst wall which revealed the presence of thick-radially striated wall with finger like projections, underlined by a thick layer of ground substance enclosing the developing metrocytes and merozoites that usually contain nearly all the structures of the apical complex and fill the interior cavity of the cyst. The cyst cavity is divided by many septa extending from the ground substance and producing large number of chambers. An experimental infection using the highly infected muscles was carried out to determine the final host, which is dog. Smears of intestinal epithelium were taken to examine the endogenous stages (gamogony and sporogony) by means of light microscopy. These stages were mainly observed as to infect the lamina propria of the posterior third of the small intestine. Gamogony and zygote formation (fertilization) occurred 2-8 days post infection, while sporulation took place within the final host 13-15 days and sporocysts were passed within faeces of the infected puppies at that time. The prepatent period of S. capracanis was 12-15 days, while the patent period was extended to 37 days. In goats, infection with S. capracanis led to the loss of weight, anaemia, abortion and even death in cases of heavy infection. While bleeding, watery faeces filled with mucous on 5th and 8th day p.i. as well as intestinal lesions are the pathogenic effects occurred in puppies after experimental infection.  相似文献   

12.
Horses are considered accidental hosts for Sarcocystis neurona and they often develop severe neurological disease when infected with this parasite. Schizont stages develop in the central nervous system (CNS) and cause the neurological lesions associated with equine protozoal myeloencephalitis. The present study was done to examine the ability of S. neurona merozoites to penetrate and develop in equine peripheral blood leukocytes. These infected host cells might serve as a possible transport mechanism into the CNS. S. neurona merozoites penetrated equine leukocytes within 5 min of co-culture. Infected leukocytes were usually monocytes. Infected leukocytes were present up to the final day of examination at 3 days. Up to three merozoites were present in an infected monocyte. No development to schizont stages was observed. All stages observed were in the host cell cytoplasm. We postulate that S. neurona merozoites may cross the blood brain barrier hidden inside leukocytes. Once inside the CNS these merozoites can egress and invade additional cells and cause encephalitis.  相似文献   

13.
Racing pigeons were artificially infected with a mixed inoculum of Eimeria labbeana (85 per cent) and E columbarum (15 per cent) and treated orally with 2.5 mg clazuril either on day 1, 2, 3, 4, 5, 6 or 7 after infection. The impact of the treatment on the different developmental stages was evaluated by oocyst output and by histological examination of the duodenum and jejunum. The life cycle always became completely interrupted, but maximal effects were noted when treatment was given on day 4, 5 or 6 after infection. Treatment during patency completely interrupted oocyst excretion within three days after dosing. Degenerative changes in schizonts and gametocytes were always observed. The histology revealed a reduced number and abnormal structure of developing merozoites; a ballooned aspect and presence of numerous small vacuoles in the microgametocytes; the absence of typical wall-forming bodies in macrogametocytes and a complete absence of oocysts. It is concluded that clazuril has a coccidiocidal effect on the asexual and sexual developmental stages of both Eimeria species, resulting in a complete interruption of the life cycle.  相似文献   

14.
The growth of Sarcocystis neurona, isolate UCD1, in continuous culture was examined in 10 cell lines to identify growth conditions and methods for the preparation of parasites free of gross host cell contamination for molecular studies. The unpredictable, slow release of merozoites in most cell lines prompted development of a method to synchronously release the parasites from infected host cells. The calcium ionophore A23187 at a concentration of 1 microM was found to release intracellular merozoites with a 40 min treatment at 37 degrees C. The release of merozoites en masse from attached host cells allowed for the rapid collection of relatively pure parasites from the culture supernatant. This release of merozoites occurred in five different host cell lines. The ionophore-released parasites were highly infectious for host cells and appeared to be morphologically identical to naturally released merozoites, except that the treated merozoites had an increased number of micronemes when examined by electron microscopy. The ionophore did not enhance the release of sporozoites from sporocysts, but freezing in the presence of 5% DMSO released sporozoites that were infectious to bovine monocytes in in vitro culture.  相似文献   

15.
A juvenile male greater shearwater (Puffinus gravis) found off the Georgia coast, United States, was lethargic, hypothermic, dehydrated, and emaciated. It was provided with supportive care but subsequently died. The coelomic cavity contained fibrinous fluid intermixed with hundreds of nematodes, some of which protruded through a perforation in the proventriculus. Nematodes were embedded in the wall of the proventriculus from the lamina propria to the serosal surface and were surrounded by granulocytes, epithelioid macrophages, multinucleate giant cells, lymphocytes, and fibroplasia. A full-thickness tear in the proventriculus was lined by heterophils and multinucleate giant cells. The nematode histomorphology was consistent with Anisakis spp. The definitive hosts of Anisakis spp. are marine mammals, which are infected through ingestion of parasitized fish and crustaceans. Marine birds are aberrant hosts of Anisakis spp., and young, inexperienced, immunocompromised birds might be more susceptible to severe infestations. Fatal anisakiasis is rarely reported in birds.  相似文献   

16.
In cases of lymphatic bovine leukemia, the nuclear pockets of the tumour cells in the lymph nodes contain part of cytoplasm and usually protrude above nucleus surface. A wall 60 to 90 nm thick forms the boundary between the nuclear pockets and cytoplasm. The wall consists of two complete nuclear membranes 25 nm thick with a 30-40 nm layer of heavily condensed heterochromatin in between. The nuclear membranes of the walls of the pockets have no nuclear pores. Extensive fusions, built from all the three layers, occur in the walls of the nuclear pockets. These pockets appear on nucleus surface when the plicae of the nuclear membrane are closed or when the apex of the plica merges with nucleus surface. Centriol is involved in the rise of the plicae of the nuclear membrane. The microtubuli inserted in the centriolar satellites on the one side merge with nucleus surface on the other side.  相似文献   

17.
Histological examination of the peripheral circulation of the ovary of 18 females of the one‐humped camel revealed a series of blood vessels with special structures. Throttle or occlusive artery was recorded in the ovarian zona vasculosa and in the cortex, and it showed an intimal cushion‐like thickening made up of intimal bolsters that formed of smooth muscle fibres and glomus cells. The smooth muscle cells of the tunica media and the tunica adventitia of throttle artery pursued a circumferential pattern. Anastomosis arteriovenosa included simple bridge‐like anastomotic vessels between arteria and venae, and glomus vessels of typical structure were demonstrated. Glomus organs were recorded in the ovary and were comprised of the tortuous glomus vessels and the related afferent and efferent vessels. Glomus cell complexes also were commonly occur at the cortex ovarii that possessed an extremely convoluted course with a hyperplastic wall and a narrow lumen. Atypical glomus vessels were demonstrated within the ovarian zona vasculosa, and the wall of these vessels was relatively thick and consisted of double tunica media with an intimal bolster. Some vessels contained an intimal bolster device of exclusively glomus cell structure (glomus bolster) with a tunica elastic interna demarcated it from the glomus cell media. Some venae represented several layers of longitudinally arranged smooth muscle fibres in the tunica media. Other venae showed wall with variable thickness. Venae with double muscular tunica media were recorded in the medulla. Some venae showed double internal elastic lamina. Also, venae with thick adventitia contained dispersed smooth muscle fibres were determined. Spirally oriented arteriole and venule were demonstrated within the cortex and medulla ovarii. Gestation sclerosis was demonstrated in ovarian zona vasculosa of pregnant females.  相似文献   

18.
The purpose of this study was to determine adequate dose ranges and to test for side effects associated with chronic treatment of fish with indomethacin. Rainbow trout Oncorhynchus mykiss were orally treated with indomethacin at various nominal concentrations: a negative control (0 mg/kg) and low (5 mg/kg), medium (10 mg/kg), and high doses (15 mg/kg) daily for 30 d. A dose-associated mortality was observed, as cumulative mortality was 3, 13, and 33%, respectively, in the three indomethacin dose groups. No lesions were observed grossly or with histopathology in the control and low-dose treatment groups. Gross lesions were observed in the medium- and high-dose groups, including skin ulcers, abdominal distension, and necrosis of abdominal wall muscle. Histopathology of fish in the medium- and high-dosage groups revealed severe granulomatous peritonitis in which a large number of foreign body type giant cells were present around proteinaceous and plant material. The inflammatory response spread from the peritoneum through the somatic muscle to the epidermis, causing lesions within all layers of the skin. A large number of bacteria were noted within the peritonitis, observed both intracellularly and in large aggregates extracellularly. Perforations occurred within the anterior intestine, and the thick muscularis layer was replaced with inflammatory tissue. The present investigation shows that chronic indomethacin treatment produces gastrointestinal side effects in rainbow trout similar to those seen in mammals.  相似文献   

19.
The cloacal bursa (bursa of Fabricius) in the guinea fowls appeared either as an oval blind sac with a short thick stalk in one group or had a pointed cranial blind end with a slightly bulging middle part that was followed by a thick caudal stalk in the other group. Both groups of bursae originated from the proctodeal wall of the cloaca and were placed dorsal to the rectum. The average length of the bursa was 18 mm while the average width at die mid section was 15 mm. The internal surface showed about 12 – 14 primary folds. Histologically, the outline of the bursa was well established by day 18 of incubation. The primary folds had also been formed. Lymphocytes had already been encountered within the framework of the bursa at this day. The epithelium bordering the tunica propria was composed principally of two layers of cuboidal cells. Epithelial buds had also formed and some were already detached from the epithelial lining. The blood vessels present were positioned just beneath the outer covering. At day 19 of incubation, most of the epithelial buds had two layers of cells arranged in a circumscribed manner while a few had three layers of cells. Blood vessels had increased in number and were deeper placed inside the bursa than previously. At day 20, the cells of the upper layer of the epithelium were dorsoventrally flattened and stained paler than the cells of the lower layer. It was possible to distinguish the cortex from the medulla and the basement lining between both zones was distinct. Tiny vesicles within the cytoplasm of the epithelial cells at the mucosa and follicles were observed. Macrophges were also observed within the gland. At day 21, blood vessels were observed in the cortex of the follicles. The maximum number of primary folds (14) had been formed. At day 22, serveral follicles had severed connections with the mucosal epithelium. The mucosal lining had dropped to a single layer of cells in some areas. Goblet cells were observed amongst the mucosal cells. A plasma cell had first appeared. By day 25, dead cells had increased quite in number and there was also an increase in number of medium and small-sized lymphocytes within the gland. By day 26, the upper layer of the surface epithelium was composed primarily of tall columnar cells with numerous large vacuoles. Macrophages had suddenly increased within the thin interfollicu-lar spaces and most of them were crowded internally with various sizes of debris. By day one post-hatch, each fold was completely filled with follicles that were separated by thin connective tissue strands.  相似文献   

20.
Skin lesions of bovine East Coast fever were examined by light and electron microscopy at 120 hours after attachment of Rhipicephalus appendiculatus ticks infected with Theileria parva. Lesions included epidermal ulcer, hemorrhage, edema, necrosis, and inflammatory cell infiltration by mostly polymorphonuclear and mononuclear (lymphoid) cells. The trophozoite state of T parva was observed in a parasitophorous vacuole and feeding on neutrophil granules. Schizonts, some in budding process, and merozoites were extracellular and among many mononuclear phagocytes (lymphoid cells). Some merozoites were in mononuclear phagocytes and a granulocyte. Some of the cells had already transformed into lymphoblasts with pseudopodia.  相似文献   

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