日本棘隙吸虫体被超微结构的研究

本文报道扫描电镜观察下日本棘隙吸虫皮式、体棘和3种感觉乳突的形态和分布。     

Redescription of <Emphasis Type="Italic">Parspina argentinensis</Emphasis> (Szidat, 1954) (Digenea: Cryptogonimidae) from freshwater fishes (Pimelodidae) in the basins of the Paraná and La Plata Rivers,Argentina, with comments on <Emphasis Type="Italic">P. bagre</Emphasis> Pearse, 1920

The type-specimens of Parspina argentinensis (Szidat, 1954) from Pimelodus maculatus Lacépède, and new material from Iheringichthys labrosus (Lütken), Parapimelodus valenciennis (Lütken), Pimelodella gracilis (Valenciennes), Pimelodus albicans (Valenciennes), P. argenteus Perugia and P. maculatus caught in the basins of the La Plata and Paraná Rivers, Argentina, were studied to elucidate its taxonomic status. The type-specimens of Parspina bagre Pearse, 1920 from Pimelodella metae Eigenmann in Lake Valencia, Venezuela, were also studied and new observations on its morphology recorded. The amendation of the generic diagnosis of Parspina Pearse, 1920 is proposed based on the study of both species, which revealed, among other features, the absence of a thin walled-membrane enclosing the male terminal genitalia. Parspina argentinensis is characterised by the following features: absence of a gonotyl; presence of a bipartite seminal vesicle, pars prostatica and ejaculatory duct; caeca of nearly equal length; uterus extending from the level of the ventral sucker to end of body; testes symmetrical to slightly oblique; ovary transversely elongate, compact and variable in shape; and the utilisation of a wide range of freshwater fishes as hosts. The tegumental surface of this species is covered with pectinate spines arranged quincuncially. Spines decrease in size and density from forebody to hindbody. There are two types of sensory papillae, ciliated and dome-shaped. Ciliated papillae are distributed on the surface of the oral region and on the dorsal and ventral surfaces of the body, whereas dome-shaped papillae are found on the surface of the ventral rim of the oral sucker associated with a ciliated papilla. Gland-duct openings are interspersed with the spines of the oral crown. In addition, the infection indices of P. argentinensis vary widely, not only among different hosts but also between the Paraná and La Plata River basins. Higher prevalences of P. argentinensis are recorded in the La Plata River, and Pimelodus albicans, P. maculatus and Iheringichthys labrosus are the principal final hosts in this area.     

Ultrastructure of the taste disc in the red-bellied toad Bombina orientalis (Discoglossidae,Salientia)

The taste disc of the red-bellied toad Bombina orientalis (Discoglossidae) has been investigated by light and electron microscopy and compared with that of Rana pipiens (Ranidae). Unlike the frog, B. orientalis possesses a disc-shaped tongue that cannot be ejected for capture of prey. The taste discs are located on the top of fungiform papillae. They are smaller than those in Ranidae, and are not surrounded by a ring of ciliated cells. Ultrastructurally, five types of cells can be identified (mucus cells, wing cells, sensory cells, and both Merkel cell-like basal cells and undifferentiated basal cells). Mucus cells are the main secretory cells of the taste disc and occupy most of the surface area. Their basal processes do not synapse on nerve fibers. Wing cells have sheet-like apical processes and envelop the mucus cells. They contain lysosomes and multivesicular bodies. Two types of sensory cells reach the surface of the taste disc; apically, they are distinguished by either a brush-like arrangement of microvilli or a rod-like protrusion. They are invaginated into lateral folds of mucus cells and wing cells. In contrast to the situation in R. pipiens, sensory cells of B. orientalis do not contain dark secretory granules in the perinuclear region. Synaptic connections occur between sensory cells (presynaptic sites) and nerve fibers. Merkel cell-like basal cells do not synapse onto sensory cells, but synapse-like connections exist between Merkel cell-like basal cells (presynaptic site) and nerve fibers.     

Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda: Gorgoderidae)

Hoole D. and Mitchell J.B. 1981. Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda : Gorgoderidae). International Journal for Parasitology11: 411–417. Ultrastructural observations have been made on the juvenile and adult stages of Gorgoderina vitelliloba from Rana temporaria. Four types of sensory papillae occur; button, rosette, ciliated and domed. Button papillae, which contain a ciliary-rootlet but lack a cilium, occur on the oral sucker, dorsal preacetabular surface and the lateral margins of the fluke. Scanning electron microscopical observations reveal that the tegumental protuberances of the papilla are transformed from a spiked or conical appearance in juvenile flukes to a rounded form in adult flukes. Rosette papillae, which also contain a rootlet, occur on the lip of the ventral sucker of both juvenile and adult flukes. Ciliated papillae only occur on the oral sucker of juvenile flukes. Domed papillae, which contain a large area of electron-dense material, occur on the internal surface of the ventral sucker of both juvenile and adult flukes. The functions of papillae and their possible role in the migration of the parasite are discussed.     

The fine structure of the newly discovered propodial ganglia of the veliger larva of the nudibranch Onchidoris bilamellata

Summary Two pairs of ganglia are found in the propodial region of the veliger of Onchidoris bilamellata: the anterolateral pair is located at the foremost corners of the propodium, and the frontal pair is located beside the propodial midline. Both sets of ganglia are positioned below the epidermis, and they are joined to the cerebral ganglia by large, common connectives. Each ganglion possesses sensory cells, nerve cells and sheath cells, and the frontal pair contains a complement of secretory cells. Externally, the propodial ganglia are manifested as sensory fields. The fields of the anterolateral pair are elliptical in shape, and each appears as a band of cilia bordering an unciliated zone. The region devoid of cilia is composed of ordinary epidermal cells, whereas the ciliated portion is comprised of dendritic endings originating from cells in the ganglion. Dendrites arise from one type of sensory cell and pass through the epidermis in bundles. Each dendrite terminates as a single cilium at the epidermal surface. Sensory fields of the frontal ganglia are key-shaped and oppose one another on the anterior end of the foot. Each field appears as a flat, circular, unciliated region which extends into a ciliated groove that runs dorsally toward the mouth. The groove contains the terminals of secretory cells, ciliated sensory cells, and the cell bodies of nonciliated sensory cells. The nonciliated sensory cells, characterized by a microvillous apex, are the dominant cells in the flattened circular zone. The space between the frontal ganglia and the epidermis is bridged by bundles of processes which are similar to those of the anterolateral ganglia. However, these tracts contain collections of the apical processes of secretory cells, the dendrites of ciliated sensory cells, and the axons of nonciliated sensory cells. Morphological and behavioral evidence indicates that the propodial ganglia serve a chemosensory function during settlement and metamorphosis.     

Tegumental ultrastructures of Echinoparyphium recurvatum according to developmental stages

The present study was performed to observe tegumental ultrastructure of Echinoparyphium recurvatum according to developmental stages. Worms (1, 3, 5 and 15-day old) were recovered from chicks experimentally infected with metacercariae from Radix auricularia coreana. One-day old worms were elongated and ventrally concave, and covered with peg-like tegumental spines except the adjacent areas of the head crown and excretory pore. Type I sensory papillae were distributed on the lip of the oral sucker, and grouped ciliated papillae were around the oral sucker. Peg-like tegumental spines were densely distributed on the anterior surface of the ventral sucker level. The ventral sucker had an aspinous tegument and no sensory papillae. Tegumental spines on the posterior surface of the ventral sucker level were sparsely distributed and disappeared posteriorly. In 3 and 5-day old worms, the tegument around the oral sucker was aspinose and wrinkled concentrically. The ventral sucker had a wrinkled tegument and many bulbous papillae. Type I sensory papillae were distributed between the bulbous papillae. Tegumental spines were spade-shaped with a terminal tip. A total of 45 collar spines including 4 end group ones on both ventral corners was alternately arranged in 2 rows. The 15-day old worms were very stout and their tegumental spines were tongue-shaped without a terminal tip. From the above results, it is confirmed that the surface ultrastructure of E. recurvatum was generally similar to that of other echinostomatid flukes. However, some features, i.e., morphological change of tegumental spines and appearance of sensory papillae on the ventral sucker according to development, and number, shape and arrangement of collar spines, were characteristic, which may be of taxonomic and bioecological significance.     

Surface ultrastructure of the plagiorchid trematode Glossidium pedatum Looss, 1899 from bagrid fish in Egypt

The present study concerned the morphology and surface ultrastructure of a plagiorchid, Glossidium pedatum, from bagrid fish of the river Nile in Egypt. Adult G. pedatum have an elongate body, tapered towards the anterior and posterior ends. Their oral sucker is small, sub‐terminal and rounded, measuring 0.200 mm in diameter. Sensory papillae around the oral sucker usually occur in small clusters of three to eight each. The ventral sucker is large, situated at the anterior end of the second third of the body, 0.299 mm in diameter, and is surrounded by three pairs of sensory papillae. Both suckers have rounded rims covered by tegumental spines. On the anterior part of the ventral surface of the body tegumental spines are small, pointed and closely spaced. A small triangular area of tegument anterior to the ventral sucker is devoid of spines. Tegumental spines on the mid‐region of the body slightly increase in size and number, especially towards the lateral aspects and posterior to the ventral sucker. Towards the posterior end of the body the spines progressively decrease in both size and number. The dorsal side exhibits similar surface features but the spines are less numerous and slightly smaller.     

纤细背孔吸虫体被超微结构的研究

本文对人工感染获得的纤细背孔吸虫Notocotylus attenuatus(Rud.,1809)成虫的体被进行了扫描电镜观察。发现虫体不同部位的体被有着不同的被式。口吸盘处为放射状条索;虫体腹面口吸盘后至中列第一腹腺前为无棘区,呈石板条块状,其余部分均为银杏叶和尖叶形体棘所覆盖。虫体背面边缘一圈为有棘区,其圈内为珠状突起结构。     

The fine structure of the buccal tentacles of Holothuria forskali (Echinodermata,Holothuroidea)

Summary Ultrastructural study of the buccal tentacles of Holothuria forskali revealed that each tentacle bears numerous apical papillae. Each papilla consists of several differentiated sensory buds.The epidermis of the buds is composed of three cell types, i.e. mucus cells, ciliated cells, and glandular vesicular cells (GV cells). The GV cells have apical microvilli; they contain bundles of cross striated fibrillae associated with microtubules. Ciliated cells have a short non-motile cilium. Bud epidermal cells intimately contact an epineural nervous plate which is located slightly above the basement membrane of the epidermis. The epineural plate of each bud connects with the hyponeural nerve plexus of the tentacle. This nerve plexus consists of an axonic meshwork surrounded in places by sheath cells. The buccal tentacles have well-developed mesothelial muscles. Direct innervation of these muscles by the hyponeural nerve plexus was not seen.It is suggested that the buccal tentacles of H. forskali are sensory organs. They would recognize the organically richest areas of the sediment surface through the chemosensitive abilities of their apical buds. Tentacles presumably trap particles by wedging them between their buds and papillae.     

Fine structure of probable mechano- and chemoreceptors in the caudal epidermis of the lugworm Arenicola marina (Annelida,Polychaeta)

Summary The caudal part of the lugworm Arenicola marina shows numerous epidermal papillae formed by a thick glandular epidermis in which ciliated sensory buds have been found. These buds comprise supporting cells and two types of receptors, R1 and R2, which are primary sensory cells whose axons are connected to the basiepidermal nerve plexus. The receptors possess several typical cilia projecting into the surrounding seawater, stout intracuticular microvilli filled with filaments, and they contain dense vesicles. The R1 cells, more numerous, show features of chemosensory cells. The rarer R2 cells have large striated rootlets surrounded by a dense sheath of fibrillar material and are probably mechanoreceptors. The physiological functions of these receptors are discussed.     

Surface ultrastructure of the tegument of Clonorchis sinensis newly excysted juveniles and adult worms.

The tegumental structures of newly excysted juveniles and adult worms of Clonorchis sinensis were studied using scanning and transmission electron microscopy. After excystation the juvenile's tegumental surface is characterized by knoblike protuberances and is armed almost entirely with numerous rows of small spines encircling the body. These spines are double- or triple-pointed on the anterior portion of the body and become single-pointed posteriorly. Four types of presumed sensory structures were observed as follow: A) ciliated knoblike papillae and B) nonciliated platelike papillae, both of which are arranged in rougly a bilaterally symmetrical pattern dorsally, ventrally, and laterally; C) rounded swellings of nonciliated papillae on the lips of the ventral and oral suckers, which are characterized in the transmission electron microscope by a rounded dense body in the apical bulb; and D) a sensory receptor with a bulbous projection having the appearance of a modified cilium, which was not found with SEM likely owing to its being enclosed by an extension of the tegument. In full-grown adult worms, the tegumental surface is knobbed or lobulated in various forms without surface spines. The tegumental structures in the adults appear to be clearly differentiated from those in the juveniles. Upraised, buttonlike papillae, each topped by a short cilium, which are similar to the Type A papillae in the juveniles, are distributed thickly around the oral and ventral suckers, and are rather randomly scattered over the remainder of the body. Some nonciliated swollen papillae were found on the lip of the ventral sucker.     

The attachment complex of brachiolaria larvae of the sea star <Emphasis Type="Italic">Asterias rubens</Emphasis> (Echinodermata): an ultrastructural and immunocytochemical study

The attachment complex of brachiolaria larvae of the asteroid Asterias rubens comprises three brachiolar arms and an adhesive disc located on the preoral lobe. The former are used in temporary attachment and sensory testing of the substratum, whereas the latter is used for permanent fixation to the substratum at the onset of metamorphosis. Brachiolar arms are hollow structures consisting of an extensible stem tipped by a crown of dome-like ciliated papillae. The papilla epidermis is composed of secretory cells (type A, B and C cells), non-secretory ciliated cells, neurosecretory-like cells and support cells. Type A and B secretory cells fill a large part of the papilla epidermis and are always closely associated. They presumably form a duo-gland adhesive system in which type A and B cells are respectively adhesive and de-adhesive in function. The adhesive disc is an epidermal structure mainly composed of secretory cells and support cells. Secretory cells produce the cement, which anchor the metamorphic larva to the substratum until the podia are developed. The relatedness between the composition of the adhesive material in the brachiolaria attachment complex and in the podia of adults was investigated by immunocytochemistry using antibodies raised against podial adhesive secretions of A. rubens. Type A secretory cells were the only immunolabelled cells indicating that their temporary adhesive shares common epitopes with the one of podia. The attachment pattern displayed by the individuals of A. rubens during the perimetamorphic period—temporary, permanent, temporary—is unique among marine non-vertebrate Metazoa.     

Ultrastructural studies on the ciliated receptors of the long tentacles of the giant scallop,Placopecten magellanicus (Gmelin)

Summary The long tentacles of the Giant scallop Placopecten magellanicus (Gmelin) have been examined with light, scanning, and transmission electron microscopy. Three types of ciliated cells have been observed, one of which is located in specialised papillae born on the distal third of the tentacle. There are two separate cell types within the papillae. Type I cells are non-ciliated supporting cells, which form a capsule within which are found the Type II cells. These cells bear up to five cilia at their apices, and it is suggested that these are the receptor cells of the organ. No function has yet been determined for the receptors, but is suggested that they might be mechanoreceptors. A third cell type, Type III cells, occur at the base of the papillae. These cells bear many cilia and also macrocilia. Another ciliated cell type occurs on the proximal two thirds of the tentacle. These cells bear many cilia that are thought to be motile and not sensory.This research was supported by National Research Council of Canada Operating Grant No. A-6444 to Dr. V.C. Barber. Additional support came from the Department of Biology and School of Graduate Studies, Memorial University. Contribution No. 249 from the Marine Sciences Research Laboratory, Memorial University of Newfoundland     

Ultrastructural features of the tegumental surface of a new metacercaria, Nematostrigea sp. (Trematoda: Strigeidae), with a search for potential taxonomically informative characters

The tegumental surface of a new strigeid metacercaria, Nematostrigea sp., which is a parasite of the freshwater fish Channa gachua (Hamilton) in central Vietnam, is described for the first time using scanning (SEM) and transmission (TEM) electron microscopy. In addition to the general tegumental surface in various parts of the body, details of the surface of the suckers, lappets and holdfast organ are presented, as are variations in the form and distribution of the body spines. As good taxonomic criteria are few in diplostomoid metacercariae at both specific and generic levels, a number of the ultrastructural features revealed may prove to represent taxonomically informative characters. These include the presence of: two rings of dome-shaped papillae localised at different levels on the rim of the oral sucker, a single ring of ciliated papillae on the inner margin of the ventral sucker and a band of dome-shaped papillae along the lateral margins of the broad body-fold in the ventral forebody; an unarmed oral sucker and anteroventral surface of the forebody, although the latter bears protuberant secretory pores; an armed ventral sucker covered by six-pointed spines, except on its rim; multi-pointed spines along the dorsal and ventral sides of the forebody, with the number of their teeth increasing posteriorly; multi-pointed spines on the forebody which gradually transform into single-pointed, more widely distributed spines on the hindbody, disappearing completely at posterior end of the body; the surface of the lappets with a particular distribution of pores leading to three types of secretory glands and three topographical modifications (areas where the surface is smooth, bears digitiform processes or bears recurved, dagger-shaped spines); and the surface of the holdfast organ which is covered with densely packed, straight or slightly curved, simple spines on its lateral surface but is smooth medially.     

Ultrastructure of the nuchal organs in the polychaete Platynereis dumerilii (Annelida,Nereididae)

Abstract. We examined the nuchal organs of adults of the nereidid polychaete Platynereis dumerilii by means of scanning and transmission electron microscopy. The most prominent features of the nuchal organs are paired ciliary bands located dorsolaterally at the posterior margin of the prostomium. They are composed of primary sensory cells and multiciliated supporting cells, both covered by a thin cuticle. The supporting cells have motile cilia that penetrate the cuticle and are responsible for the movement of water. Subapically, they have a narrowed neck region; the spaces between the neck regions of these supporting cells comprise the olfactory chamber. The dendrites of the sensory cells give rise to a single modified cilium that crosses the olfactory chamber; numerous thin microvillus-like processes, presumably extending from the sensory cells, also traverse the olfactory chamber. At the periphery of the ciliated epithelium runs a large nervous process between the ciliated supporting cells. It consists of smaller bundles of sensory dendrites that unite to form the nuchal nerve, which leaves the ciliated epithelium basally and runs toward the posterior part of the brain, where the perikarya of the sensory cells are located in clusters. The ciliated epithelium of the nuchal organs is surrounded by non-ciliated, peripheral epidermal cells. Those immediately adjacent to the ciliated supporting cells have a granular cuticle; those further away have a smooth cuticle. The nuchal organs of epitokous individuals of P. dumerilii are similar to those described previously in other species of polychaetes and are a useful model for understanding the development of nuchal organs in polychaetes.     

Scanning electron microscope study of epidermal surface of six ectosymbiotic Temnocephala species (Platyhelminthes) from Argentina

The epidermis of six ectosymbiontic Temnocephala species (T. axenos, T. chilensis, T. digitata, T. microdactyla and T. pignalberiae from freshwater crustaceans and T. iheringi from a mollusc) from Argentina examined using scanning electron microscopy revealed characters indicating their relationships with other members of the Platyhelminthes and with the congeneric Australian and New Zealand species. In all species, the whole surface is covered with microvilli and no locomotory cilia were observed. Aggregates of monociliated receptors are on the tentacles of all species and on the ventral surfaces of three. Furthermore, T. axenos and T. chilensis show other ciliated structures interpreted as collar receptors, such as those described for some turbellarian groups (e.g. Proseriata and Rhabdocoela). Two species (T. digitata and T. iheringi) show structures that are probably related to the duo-gland adhesive system.     

On the structure of the pulmonate osphradium

Summary The osphradium of Planorbarius consists of a blindly-ending ciliated canal, formed by an infolding of the mantle epithelium, and a basal ganglion of nerve cells which is comparable in complexity with ganglia of the central nervous system. The distribution of cell types in the osphradial epithelium is specialised so that three regions can be recognised; the ciliated, the secretory and the sensory regions. The basal sensory region of the canal epithelium consists of ciliated cells and is innervated by sensory neurones of the osphradial ganglion. The middle secretory region contains mainly of mucus-secreting cells and the epithelium adjacent to the osphradial aperture of ciliated cells and secretory cells of a second type. The sensory neurones of the osphradial ganglion are bipolar or of a modified monopolar type. Other monopolar neurones, similar to those common in the central nervous system are of non-sensory function. The osphradium of Paludina, although of typical prosobranch form, possesses ciliated pits similar to the single canal of Planorbarius, which may indicate a shared modality of receptor function. A definite function cannot be ascribed to the pulmonate osphradium based on morphological evidence alone.     

The fate of specific motoneurons and sensory neurons of the pregenital abdominal segments inTenebrio molitor (Insecta : Coleoptera) during metamorphosis

The anatomy and innervation of the lateral external muscle and sensory cells located in the ventral region of pregenital abdominal segments were examined at the larval and adult stages ofTenebrio molitor (Coleoptera). All seven muscles located in this region degenerate during the pupal stage, whilst only the lateral external median (lem) appears in the adult. Backfillings of the motor nerve innervating this muscle reveal that, at both larval and adult stages, it is innervated by ten neurons. Intracellular records from the muscle fibres show that two neurons are inhibitory, and at least five are excitatory. There are also two unpaired neurons. A variety of sensory organs are located in the ventral region of the larvae, whilst only campaniform sensilla are found in the adult. At both stages, the innervation pattern of the sensory nerve branches is very similar. Also, the central projections of the sensory cells occupy similar neuropilar areas. Finally, prolonged intracellular records from the lem muscle revealed that, at the larval stage, it participates only in segmental or intersegmental reflexes, whilst in the adult it has a primary expiratory role in ventilation. The results show that extensive changes occur in the number of muscles located in the ventral region of the pregenital abdominal segments, as well as in the arrangement and number of sensory neurons, in the structure of the exoskeleton, and even in the central nervous system. In contrast, only minor changes are observed in the sensory and motor nerve branches, in the sensory projections, and in the number and the location of the motoneurons innervating the lateral external median muscle. Correspondence to: G. Theophilidis     

Morphological,ultrastructural and histochemical investigation of epipodial sensory structures of Haliotis tuberculata (Gastropoda: Haliotidae)

In this study, we describe the microstructure and ultrastructure of the epipodial papillae and epipodial tentacles of Haliotis tuberculata using light and electron microscopy. The epipodial papillae vary morphologically; they are subdivided into several subpapillae whose surface is covered by small micropapillae. The epipodial tentacles are large extendable conically elongated structures whose surface is differentiated in two regions: the dorsal region with long corrugated folds, and a ventral region composed of three parts, a basal part with the same structure as the dorsal, a middle part with shorter corrugated folds and an apical part with large micropapillae. Although the thin sections and ultrastructure examination show that the epithelium of both organs is morphologically similar and composed of supporting cells, sensory cells and different types of secretory cells, there is a certain specialization in their secretory product. Although the epithelium of both structures was positive for acidic glycoconjugates, the tentacle epithelium was also positive for neutral sugars. Further specific differences were revealed by lectin histochemistry. Because papillae and tentacles can be extended or retracted depending on environmental conditions, they probably have tactile and olfactory functions.     

Distribution,abundance, and size of rhabdoids in Dugesia polychroa. (Turbellaria: Tricladida)

The ontogenetic changes in the distribution, abundance, and size of rhabdoids were examined in an undisturbed laboratory population of Dugesia polychroa. Irrespective of triclad age, rhabdoids in the epidermis and parenchyma were more abundant on the dorsal than the ventral side of the body. No significant differences were found in the abundance of epidermal or parenchymal rhabdoids among the anterior, medial, and posterior regions of the body. Rhabdoid number and size changed significantly with triclad age, with a marked depression coinciding with the onset of cocoon production. Rhabdoid discharge was correlated with physical and/or physiological disturbance and occurred in the absence of any overt environmental disturbance. Simple allometric relationships were observed between rhabdoid size and number on one hand and body plan area on the other. Different allometric trends were observed from field-collected individuals compared to the undisturbed laboratory population. The potential function of rhabdoids in the Tricladida is discussed in light of these findings.