首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A detailed study of the surface topography of the echinostome digenean Mesorchis denticulatus (Rudolphi 1802) Dietz 1909 was carried out using the scanning electron microscope. The surface area of the redia is increased by microvilli, and ciliate sensory structures are common around the mouth. The cannibalistic behaviour of the rediae is demonstrated by rediae which have the posterior end and tail of extraredial cercariae protruding from the mouth. The partly devoured cercariae had occasionally — apparently as a defence reaction — covered their bodies with a thick layer of cystogenous material, which, however, does not protect them from being eaten.The surface area of the tegument of the youngest extraredial cercariae is increased by small microvilli or knobs with a presumed function in nutrient absorption. The knobs disappear when the cercariae are fully developed. Flattened spines occur peripherally in the suckers. Different types of ciliate structures are especially common anteriorly. The infective metacercariae, which occur in the gill filaments of euryhaline fishes, have conspicuous collar spines and smaller pointed spines occur on most of the body surface.The spines continue to grow in the experimental final host, chickens. The flattened spines of the oral sucker remain, whereas those of the ventral sucker disappear. The ventral area between the suckers is spineless.  相似文献   

2.
The purpose of the study is to explore the role of humoral immunity against Schistosoma mansoni infection in C57BL/6 mice using highly resistant rabbits that had been exposed to three separate immunizations with ultraviolet (UV)-irradiated cercariae (8,000 attenuated cercariae/rabbit in each immunization), and their sera were tested for their ability to transfer protection against S. mansoni challenge. The present study showed the reduction in challenge worm burden had reached 32.76–43.64% when compared with recipients of normal serum or no serum. The surface topography of the worms collected from immunized mice with either normal rabbit sera (NRS) or vaccinated rabbit sera (VRS) revealed severe tegumental alterations, especially in the VRS group. Worms collected from groups that were immunized by NRS or VRS postinfection (200 normal cercariae/mouse) by day 42. Worms from group immunized with NRS showed damage in the tegument, characterized by severe swelling or erosion of tegumental folds, accompanied by changes in tubercles, swelling, shortening, and loss of spines in male worms. The alteration in female tegument was characterized by swelling of tegumental folds, atrophy of ventral sucker, damage of sensory papillae along all the body, severe peeling in some regions, and appearance of few small blebs. VRS induced more severe tegumental damage than NRS in both male and female worms. Severe shrunken vesicles were protruded from the surface between the two suckers. The tegument of the male showed a collapse of tubercles followed by the appearance of vesicles on their surfaces, fusion, erosion, and superficial focal peeling of tegumental folds. In the female worms, severe damage to the oral sucker, the surface between the two suckers, extensive peeling, severe swelling of the tegument, and damage of sensory papillae. In conclusion, the present study support the hypothesis that high levels of antibodies were developed in rabbit sera after multiple exposures to attenuated cercariae of S. mansoni. Furthermore, immunization might have transferred protection against the infection, indicated by severe morphological alterations, a sign of elimination of the worms. Further investigation is being carried out to reveal the molecular mechanisms underlying the transfer of protection.  相似文献   

3.
Summary The tegumental ultrastructure of the cercaria of the liver fluke,Clonorchis sinensis (Cobbold, 1875), was studied by scanning and transmission electron microscopy. The body surface is almost encircled by many rows of regularly arranged spines. The tegumental syncytium of the body contains many rod-shaped dense granules and central electron-lucent bodies, neither of which are present in the tail tegument. There are four rows of hooked teeth and modified spines on the oral cone. These teeth are differentiated morphologically and probably functionally from the other body spines. Disc-shaped papillae with long or short cilia are distributed on the body in a bilaterally symmetrical pattern dorsally and ventrally. There are 30 to 37 papillae with much longer cilia laterally. Four pairs of papillae were found on the tail. From their structure and location these papillae appear to have a mainly tango-or rheoreceptive function. Another type of sheathed papillae is situated around the oral sucker. The cuticular tegument is expanded laterally at the base of the tail, forming a characteristic sac-like structure.This work was supported in part by a Scientific Grant (No. 037036) from the Ministry of Education, Japan  相似文献   

4.
In the excysted metacercaria, the whole fluke surface was covered with peg-shaped tegumental spines. Ciliated sensory papillae (type I) were concentrated around the oral sucker, and non-ciliated sensory papillae (type II) were aligned on the lip of oral and ventral suckers. Several type II papillae were aligned laterally with linear symmetry between the oral and ventral suckers. In juvenile flukes, cytoplasmic processes were band-shaped on the anterior half of the body surface and velvety on the posterior half. In adult flukes, cytoplasmic processes were differentiated into velvety processes, and densities of tegumental spines were reduced on the posterior half of the body. Flukes grew to be elongated and leaf-like as adults and retained a surface ultrastructure that was similar to that of juveniles in terms of the distribution of tegumental spines and sensory papillae. From the above results, the authors suppose that the marked differentiation of cystoplasmic processes and the reduced density of tegumental spines observed on the posterior half of the body surface are closely related to the development of reproductive organs therein.  相似文献   

5.
The tegumental ultrastructure of the intestine fluke Deropristis inflata was studied using scanning and transmission electron microscopy. The surface of the tegument was covered by transverse cytoplasmic ridges from which protrude numerous thorn-like spines showing crenelated tips on the posterior part. Spines were arranged in staggered rows. Cobblestone-like units of the tegument were observed on a semicircle-shaped formation over the oral sucker. A tegumental excrescence was observed in the dorsal anterior side of the fluke. Ultrastructural study revealed that the tegument of D. inflata had a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. Cytoplasmic bridges allowed transit of secretory vesicles and granules packed in gland cells. Two types of sensory structures were examined. Type 1 sensory receptor was a button-like uniciliated papilla mounted on a folded tegumental base and surrounded by cytoplasmic ridges. This receptor consisted of a nerve bulb and a cilium that extended from a centriole. Type 2 sensory receptor was a smooth bulb-like non-ciliated papilla. It was only recovered on the ventral sucker. This receptor consisted of a nerve bulb enclosing an ovoid electron-dense structure. For both receptors, the nerve bulbs contained numerous mitochondria, nerve fibers, and electron-lucent material. Particular distributions of the sensory receptors were observed with a concentration on the anterior third of the body around the oral and ventral suckers. Diagrams were made to help in understanding the nature of these structures.  相似文献   

6.
Ten adult Quinqueserialis quinqueserialis specimens were removed from the intestine of a naturally infected muskrat, and scanning electron microscopy was used to study the morphological characteristics of the trematodes. The mature trematode, which was easy to recognize by the monostome holdfast organ, with no anterior cone, measured 2200–2500 μm in length by 900–1050 μm in width. The body was elongated and tapering at the anterior end, but the posterior end was rounded, and in some specimens was slightly truncated. The mouth opening lay at the anterior end and was surrounded by the oral sucker, which was round, small to medium in size, and subterminal. The tegument of the rim and inside of the oral sucker was smooth and had two types of papillae, domed and rosette papillae. Around the oral sucker, tegument was covered with sharp, pointed spines. The common genital pore was located on the median line of the body, posterior to the oral sucker. The cirrus had smooth tegument at the base and was armed with numerous conical spines throughout its length. The ventral surface was concave and provided with five distinct longitudinal rows of ventral papillae, which extended from the anterior to the posterior end of the body. Each row consisted of 15 to 20 papillae, making 81 to 88 papillae in all. These papillae were variable in size. In most specimens, the papillae were simple knob-like structures, but in some cases, they appeared to be bi- or trifurcate. The tegument at the base of each ventral papilla showed minute spiny pattern, but it was smooth or folded on top and had small rosette and ciliated papillae. Tegument at the edges of the worm was smooth in the mid-parts, spiny on lateral parts, and included rosette papillae. The dorsal surface of the worm was smooth and slightly convex, and the tegument was provided with two large domed papillae in one third of the anterior end of the dorsal part, few thick spines in the mid-part, and excretory pore at the level just posterior to the end. No spines or papillae were seen around the excretory pore.  相似文献   

7.
The effect of the deacetylated (amine) metabolite of diamphenethide (10 g/ml) on the tegumental surface of Fasciola hepatica over a 24 h period in vitro has been determined by scanning electron microscopy. Blebbing begins around the oral sucker after 3 h and then passes backwards along the body, reaching the ventral sucker and midbody by 6 h, and finally the posterior end of the body (by 12 h). Initially, the blebs are small, the tegument surrounding the spines is swollen and the tegument generally has a smooth, swollen appearance. This submerges the spines below the body surface. At higher magnification the surface is seen to bear microvillous-like projections in addition to the blebs and surface pitting is deeper than normal. Later on, the blebs increase in size and burst, causing lesions and loss of spines. Lesions begin to appear on the oral cone and ventral sucker after 6 h, in the midbody by 12 h and on the dorsal surface of the posterior region after 24 h. By this time the damage is extensive: around the oral and ventral suckers, and over large areas of the oral cone and midbody region the tegument has been stripped off to expose the basal lamina beneath. The dorsal surface of the fluke is consistently more severely affected than the ventral surface.  相似文献   

8.
The tegument ultrastructure of the intestinal fluke Aphallus tubarium was studied for the first time with the use of scanning and transmission electron microscopy. New details on morphology were recorded. The ultrastructural study revealed that the tegument of A. tubarium had a syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. The surface of the tegument is covered with pectinate spines arranged quincuncially. As anterior-posterior differences were observed, particular attention was given to spines. Spines decrease in size and density from the anterior part of body to posterior part. Two types of sensory structures were identified, uniciliated and dome-shaped. Type 1 sensory receptors were outgrowths bearing groups of papillae with shorter and rigid apical seta visible on the anterior part of body surface, encircling the worm. Type 2 sensory receptors was dome-shaped papillae devoid of cilia, found mainly around the oral sucker. Diagrams of spines and sensory receptors were made to help in understanding the nature of these structures. Surface morphology may prove to be useful in distinguishing Aphallus spp with other Cryptogonimidae.  相似文献   

9.
A detailed study of the surface topography ofConcinnum epomopis (Dicrocoeliidae) was carried out with a scanning electron microscope. The ultrastructural observations demonstrate the absence of spines on the body surface; however, the tegument is complex, exhibiting distinct, minute, lateral undulations, predominantly on the ventral side. The pattern of the tegumentary lamellae in different regions of the body is described. Two types of sensory papillae, the pit-type and the aciliate dome-type exhibit a uniform and distinct pattern of distribution on the surface of the worm. The pit-type is limited to the ventral depression anterior to the oral sucker. The pre-acetabular ventral genital opening, the posterior terminal excretory pore and pre-equatorial opening of the Laurer's canal are devoid of structural specialization and sensory papillae. The cylindrical, everted cirrus is covered with anastomosing, longitudinal lamellae of tegument, between which lie minute aggregates of protuberances forming the cirral papillae.The topography of the worm surface in relation to function and taxonomy is discussed.  相似文献   

10.
Scanning electron microscopy (SEM) has been used to study the tegument and related structures of adult Dicrocoelium dendriticum. Its body shape, suckers, common genital pore, Laurer's canal pore, excretory pore, and cirrus are described as seen under SEM. The tegument is devoid of spines and presents an interlacing, ridged network which covers the entire body. The pattern of ridges on the body surface is not homogeneous; details of the pattern in each region are described. SEM of the body surface reveals the high density of tegumental vesicles on ridge walls and valley floors. The tegument also bears small finger-like projections in certain areas. The authors suppose that the vesicles and finger-like projections of the tegument may well be the same structure in different functional stages. Some considerations on the significance of the tegumental differences in each body region are given. Four types of tegumental papillae occur on the suckers and body surface of D. dendriticum: button, rosette, plate, and domed. The dimensions, shapes, position, and arrangement of the papillae are described.  相似文献   

11.
Five adult Fascioloides magna specimens were recovered from the livers of naturally infected calves from Texas, USA. Scanning electron microscopy was used to study the morphological characteristics of the trematodes. These mature flukes measured 35–100 mm in length by 15–25 mm in width and had an oval dorsoventrally flattened body, with no anterior cone. The tegument was armed with sharp spines. Around the oral and ventral suckers, some of the spines were small, with a sharp point, while others had serrated edges with 15–22 sharp points. The surface of the oral sucker was covered by an interesting pattern of tegument, small dome-shaped and ciliated papillae. The ventral sucker showed a smooth surface and two unknown spine-like structures. There were fewer spines at the base of the genital pore than on other parts of the anterior end of the worm. At the anterior end of the ventral side, well-developed spines were observed, while at the posterior end of the ventral side, the spines were small, mostly with one or three points and blunted edges. At the posterior end of the dorsal side, the spines became progressively fewer, smaller, and shorter. Around the excretory pore, the tegument was folded, with no spines, and small groups of dome-shaped and ciliated papillae were present. The cirrus organ showed a smooth surface, with small pores on the dorsal side and small groups of tiny spines between the folds. The eggs measured 168 × 101 μm and had a protoplasmic appendage at the pole opposite the operculum. At the posterior end of the dorsal side, and toward the right, a pore with a very thin rim was present, which could be the terminus of Laurer’s canal.  相似文献   

12.
 Transmission electron microscope studies of the tegument of the tropical marine fish monogenean parasite Pseudothoracocotyla indica describe surface specialisations and detail the ultrastructure of the tegument and the haptor. The tegument consists of a syncytium, numerous electron-dense granules, electron-lucent vesicles and large multivesicular bodies. The posterior tegumental syncytium is infolded to form tegumental ridges that are present on both the ventral and dorsal surfaces. A thin coat of glycocalyx is present on the tegument surface. In contrast, the tegumental syncytium of the haptor is relatively thin, containing electron-dense granules and various-sized electron-lucent vesicles. Exocytosis of the electron-dense and electron-lucent vesicles apparently occurs in the syncytium of the haptor and general body surface. Tegumental damage was observed on the dorsal surface in the mid-body region and may possibly have been due to natural mechanical forces. The haptor consists of electron-dense clamp sclerites embedded within a matrix covered by the tegumental syncytium. The sclerites are connected to each other and to the basal lamina by radially oriented muscle fibres. The haptor is richly supplied with non-myelinated nerve axons. Both uniciliated and non-ciliated presumed sensory structures are present on the body surface and haptor. Uniciliated sensory structures were found mainly around the oral sucker. Groups of neurons and nerve processes containing neurosecretory vesicles were frequently observed in the vicinity of the clamps. Electron immunogold labeling studies demonstrated that neuropeptide F [NPF (Moniezia expansa)] immunoreactivity was confined to electron-dense-cored neurosecretory vesicles in nerve fibres from the posterior and haptor regions of the fluke. Received: 8 February 1996 / Accepted: 10 April 1996  相似文献   

13.
Ultrastructure of daughter sporocysts and cercariae ofSchistosoma japonicum were studied 2 and 4 months after infection ofOncomelania hupensis hupensis. The body walls of daughter sporocysts are similar at all infectious stages. They consist of an external syncytial tegument on a basement membrane, and an internal cellular subtegument surrounding a body cavity containing developing cercariae. The cercariae embryos develop 2 months after infection from germinal balls in the brood chamber of the daughter sporocyst. They are at first enveloped by a primitive epithelium rising from the daughter sporocyst. Four months after infection, the cercarae were almost fully developed and the primitive epithelium had degenerated. The body wall of the cercaria consists of a thin tegument covered by a surface coat of fibrous material and connected to the subtegumental cells by cytoplasmic processes. The matrix of the tegument contains numerous dense bodies, vacuoles, and spines. Two types of sensory structures-uniciliated and multiciliated —are found at the anterior tip of the cercaria. There are five pairs of penetration gland cells of two distinct types differentiated by the morphology of secretory granules. Flame cells are found in both daughter sporocysts and in cercariae. The cilia of the flame cells are characterized by the typical 9 and 2 cilium pattern.Abbreviations A Granules of the penetration glands, type A - B Granules of the penetration glands, type B - BB Basal body - BC Brood chamber - C1 Young cercaria - C2 Mature-cercaria - CA Canaliculi - CE Cercarial embryo - CF Cilia of flame cell - CM Circular muscular fibre - CP Cytoplasmic process - CR Cristalloid structure - CS Cilia of sensory organelle - D Desmosomes - DE Dendron - DP Duct of penetration gland - EB Excretory bladder - EC Excretory canals - ER Endoplasmic reticulum - F Folds of cercarial tegument - FL Fibre layer - FV Food vacuole - GC Germinal cell - L Lipid vacuole - LM Longitudinal muscular fibres - M Muscular fibre - MI Mitochondrium - MS Multiciliated sensory organelle - MT Microtubules - MV Microvilli - N1 Nucleus of subtegument cell of the daughter sporocyst - N2 Nucleus of tegument of the cercarial embryo - N3 Nucleus of the germinal cell - NS Neurosecretion - NV Neurosecretory vesicle - PE Primitive epithelium of cercarial embryo - R Rod-like body - S Spine - SB Spherical body - SC Surface coat - SD Septate desmosomes - ST Subtegument - STC Subtegumental cell - TC Tegument of cercaria - TD Tegument of the daughter sporocyst - US Uniciliated sensory organelle - VE Vesicles  相似文献   

14.
Summary The tegument of the cercaria of Schistosoma mansoni resembles that of the adult in its basic organization but differs considerably in detail. The outer level of the cercarial tegument is thinner and contains several types of inclusion not found in the adult. Only rod-like bodies are characteristic of both stages. Although the cercarial spines are smaller than those of the adult they possess an identical substructure. The uniciliate sensory structures of the cercaria differ from those of the adult in that the cilium of the cercarial structure is not ensheathed in tegumental material. A second type of sensory structure bearing several cilia is located at the anterior tip of the cercaria. Three morphologically distinct types of penetration gland can be distinguished and the content of each is described.  相似文献   

15.
The penetration apparatus of the cercaria ofPygidiopsis ardeae Køie, 1990 (Heterophyidae) is provided with five large preoral hooklets. Various types of presumably sensory structures surround the small oral aperture. Small, pointed spines protrude throughout the cercarial body. After parasite penetration and encystment in the fish intermediate host, the metacercarial tegument increases its absorptive area by developing irregular projections. Concurrently the pointed spines become scale-like and serrated. The tegumental outgrowths appear to have regressed in infective metacercariae. The external surface of mature worms removed from the intestine of domestic chickens does not differ from that of infective excysted metacercariae. Adults taken from experimentally infected chickens were identical to specimens obtained from naturally infected herons.  相似文献   

16.
Scanning electron microscopy is used for the first time to study the surface topography of Ithyoclinostomum dimorphum (Diesing, 1850), collected from Ardea cocoi Linnaeus, 1766 on the floodplain of the upper Paraná River Basin, Brazil. The body surface exhibits annular furrows, ridges and sensory papillae but no spines, and the tegument is reticulate. The oral sucker is terminal, bears radial furrows and is surrounded by a collar. The ventral sucker is located close to the oral sucker but lacks a collar. When extruded, the cirrus can be seen to bear papillae in its base, and the aperture of the ejaculatory duct is visible distally. The excretory pore is dorso-subterminal. Various incrustations and secretions are present on the body surface. These detailed observations make it possible for to us speculate on the functional significance of some of our findings in relation to the large size and contractile nature of these worms, and their ability to survive and mate in an apparently hostile environment.  相似文献   

17.
 The tegumental surface of Artyfechinostomum sufrartyfex as viewed under the scanning electron microscope revealed the presence of double rows of spines in the collar. The dorsal surface (6–8 rows) and the ventral surface are provided with posteriorly directed spines. The normal body surface of Fasciolopsis buski shows posteriorly directed scales throughout the ventral surface; the dorsal surface is free of any scales but has domed, coarsely distributed papillae. When treated in vitro with ethanol root-tuber extract of Flemingia vestita, an indigenous medicinal plant in Meghalaya, India, at a concentration of 5, 10, and 20 mg/ml phosphate-buffered saline (PBS), A. sufrartyfex became paralyzed within 1.1–1.4, 0.8–1.0, and 0.3–0.5 h, respectively. Following similar treatment, F. buski took 3.0–3.6, 1.5–2.0, and 0.6–0.8 h, respectively, to reach a paralytic state. Oxyclozanide B.P. was used as the reference drug and paralyzed the worm, taking slightly less time than the crude extract for both species of flukes. Stereoscanning observations on the tegumental surface of treated (20 mg extract/ml PBS) A. sufrartyfex revealed sloughing off of most of the spines or their deformation as well as wrinkles and rupture of the general tegument. Severe tegumental alterations and deformities were also displayed by F. buski exposed to 20 mg extract/ml PBS. Received: 21 June 1995 / Accepted: 29 August 1995  相似文献   

18.
Magnivitellinum corvitellinum sp. nov. is a parasite from the intestine of tamboatá Hoplosternum littorale, a freshwater catfish from Paraná River, Brazil. This species has an elongate body, a small cirrus-sac, testes in the posterior half of the body and well-developed follicular vitellines. It differs from the only other species in the genus, M. simplex, in having tegumental spines along the body, ventral sucker distinctly bigger than oral sucker, oesophagus absent and vitellaria extending from posterior margin of ventral sucker to near posterior extremity of body. An emendation of the generic diagnosis is proposed in view of the presence of tegumental spines along the body, absence of oesophagus, relative size of ventral and oral suckers and uterus covering caeca from the level of ventral sucker to the end of caeca. This is the fourth trematode species recorded parasitizing Hoplosternum littorale.  相似文献   

19.
The fine structure of the tegument of three trematode species,Schistosoma mansoni, Dicrocoelium dendriticum, andFasciola hepatica, was studied by means of light scanning (SEM) and transmission electron microscopy (TEM) after in vitro exposure to 0, 1,10, and 100 g/ml of the anthelmintic praziquantel for 5, 15, 30, and 60 min. InS. mansoni andD. dendriticum the resulting vacuolization of the tegument was confined to numerous small areas scattered all over the surface of the parasites and this finally led to the disruption of the apical tegumental layer. No changes were found in the tegument ofF. hepatica after treatment with praziquantel.Abbreviations B Bubbles - BL Basement layer - CM Circular musculature - GA Genital atrium - GC Gynaecophoric canal - IB Inclusion bodies - IM Interstitial material - LM Longitudinal musculature - MI Mitochondria - OS Oral sucker - R Ridges - S Spine - SP Surface pits - T Tubercle - TG Tegument - V Vacuoles - VS Ventral sucker - SEM Scanning electron microscopy - TEM Transmission electron microscopy Dedicated to Professor G. Piekarski on the occasion of his 70th birthday  相似文献   

20.
Summary A detailed study on macro- and microtopography, body form and tegument architecture, of Leucochloridium sp. has been carried out by SEM. Three types of sensory structures (presumed) have been distinguished on body tegument: a domed aciliate papillae, pits and depressions in the body surface. The distribution of these is described and their function discussed. Both single-and multipointed spines were found. The development, size, shape and distribution of these are described and also discussed in relation to functional morphology. These results on tegument topography of Leucochloridium sp. revealed by SEM, have also been compared with the existing, scattered information on this topic on other species of Leucochloridiidae.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号