The chetotaxy of the cercaria ofOpisthioglyphe locellus Kossack 1910 (Trematoda,Plagiorchiidae)

The distribution of the tegumentary papillae (chetotaxy) was studied for the cercaria ofOpisthioglyphe locellus. The cercariae, which emerge from the freshwater snailPlanorbarius corneus L., were treated according to the method of Ginecinskaja and Dobrovol'skij (1963). The papillae were demonstrated after the nomenclature of Richard (1971). The results were identical for cercariae from naturally infectedPlanorbarius corneus from a pond near Ulm (Germany) and experimentally infected, laboratory-reared snails of the same species. The papillae were distributed symmetrically with few individual variations. The association of the trematode with the subfamily Opisthioglyphinae is corroborated by the chetotaxy of the cercaria. This method also allows the distinction of the cercaria from the most related species. The fact that the excretory system of the cercaria ofOpisthioglyphe locellus shows common characteristics with other cercariae of the Opisthioglyphinae (Bock 1982), just like the chetotaxy, emphasizes the taxonomic importance of both criteria.     

Ultrastructure of the developing protonephridial system of the cercaria ofPhilophthalmus sp. (Trematoda,Digenea)

The fully developed flame bulb ofPhilopthalmus exhibits the structure characteristic of Trematoda and Monogenea: external and internal ribs forming a weir, external and internal leptotriches, and two longitudinal cytoplasmic cords connected by a septate junction. The proximal canal has a septate junction and surface lamellae. In developing cercariae, perikarya of terminal and proximal canal cells are close together, and sheetlike outgrowths of the terminal cell are externall surrounded by cytoplasm of the proximal canal cell containing a septate junction. Internal outgrowths and external cytoplasm are connected by many membranes, i.e. desmosome-like structures. Internal sheets break up into internal ribs, and the external cytoplasm breaks up into external ribs, external and internal ribs connected by the filtration membrane. The developing distal excretory duct possesses a septate junction and many branching and looping lamellae. A comparison ofPhilopthalmus with the cestodeAustramphilina elongata, the only other platyhelminth species in which the development of the protonephridia has been studied at the ultrastructural level, revealed that the two species differ in the presence and absence, respectively, of a septate junction in the flame bulb at an early stage of development.Financially supported by the Australian Research Council and the University of New England     

Infektionsversuche mit dem Lungenwurm des Igels,Crenosoma striatum (Zeder, 1800)

Zusammenfassung In experimentellen Untersuchungen mit dem Lungenwurm des Igels, Crenosoma striatum, wurden vier Land-, fünf Schlamm-, vier Wasser- und drei Nacktschneckenarten im Hinblick auf ihre Eignung und Bedeutung als Zwischenwirte überprüft und zahlreiche Tierarten wie Igel, Maulwurf, Goldhamster, Meerschweinchen, Kaninchen, Albinoratte, Albinomaus, Hausmaus, Baumwollratte, vielstrichige Maus (Mastomys natalensis), Hausspitzmaus, Hund, Frettchen, Katze und Feldspitzmaus mit Lungenwurmlarven infiziert.Bei 13 der im Experiment verwendeten Schneckenarten konnte ein Angehen der Infektion in unterschiedlicher Stärke beobachtet werden. Die Schneckenarten Cepea nemoralis, Cepea hortensis und Arianta arbustorum erwiesen sich als Zwischenwirte besonders geeignet. Durch die Infektion von zwei Igeln konnte die Infektionstüchtigkeit der aus diesen Schnecken isolierten dritten Larven bewiesen werden.Bei allen übrigen Tierarten gelang es nicht, patente Infektionen zu setzen, obgleich bei einigen von diesen zu verschiedenen Zeiten post infectionem dritte und vierte Stadien von Crenosoma striatum in den Lungen nachweisbar waren. Crenosoma striatum kann deshalb als ein sehr wirtsspezifischer Parasit bezeichnet werden.

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Infection experiments with the lungworm of the hedgehog, Crenosoma striatum (Zeder, 1800)

Summary In infection experiments with the lungworm of the hedgehog Crenosoma striatum several species of snails such as four land snails, five mud snails, four aquatic snails and of three slugs were tested on their susceptibility and importance as intermediate hosts. Also various animals, such as the hedgehog, the mole, the golden hamster, the guinea-pig, the rabbit, the albino rat, the albino mouse, the house mouse, the cotton rat, the multimammate mouse (Mastomys natalensis), the house-soricine, the dog, the ferret, the cat and the field-soricine were infected with larvae of this lungworm.In thirteen of the different species of snails and slugs used in these experiments the infections became patent in different degrees of intensity. Cepea nemoralis, Cepea hortensis and Arianta arbustorum were found especially suitable as intermediate hosts. The infectiousness of the third stage larve, isolated from these snails, could be demonstrated in two hedgehogs. Although the third- and fourth stage larvae of Crenosoma striatum could be recovered from the lungs of some other animals at various times post infectionem, no patent infection could be produced in all other animals. It may therefore be concluded, that Crenosoma striatum is a highly hostspecific parasite.

     

Cercarial chaetotaxy of Echinostoma revolutum (Froelich, 1802) and E. echinatum (Zeder, 1803) (Trematoda, Echinostomatidae)

The life-cycles of Echinostoma revolutum and E. echinatum were carried out by using cercariae emitted by naturally infected Molluscs. E. revolutum strain was issued from Lymnaea auricularia, E. echinatum from Lymnaea truncatula and Planorbis planorbis, Planorbarius corneus produced an Echinostome which may possibly be E. echinatum or another species E. sp. Metacercarial stages and adults were obtained from laboratory experimental hosts. None of these adult Echinostomes displayed well-defined morphological differences: nevertheless their respective larval stages exhibited discrepancies used for species diagnosis. Cercarial chaetotaxy is given for every batch and compared with that of other species described as E. audyi, E. lindoense and E. caproni; discriminating features are discussed.     

Occurrence and distribution of putative neurotransmitters in the frog-lung parasiteHaplometra cylindracea (Trematoda: Digenea)

The localistion and distribution of the cholinergic, serotoninergic and peptidergic components of the nervous system of the frog-lung flukeHaplometra cylindracea have been determined by the application of standard enzyme cytochemical and immunocytochemical techniques to cryostat sections and whole-mount preparations. Cholinesterase activity (ChE), as indicative of acetylcholine, has been demonstrated cytochemically in the CNS and PNS; however, the anterior ganglia were notably unreactive. The occurrence of serotonin was examined by an indirect immunofluorescence technique, and immunoreactivity (IR) was demonstrable in small, paired anterior ganglia and in fine nerve fibres associated with the somatic muscle, cirrus and gonopore. The peptidergic protion of the nervous system was investigated using antisera to 17 mammalian regulatory peptides and the invertebrate peptide FMRFamide, and was visualised by both indirect immunofluorescence and confocal scanning laser microscopy. Positive immunostaining occurred with antisera raised against pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP), peptide histidine isoleucine (PHI) and FMRFamide. Immunoreactivity to PP, PYY and FMRFamide was widespread throughout the nervous system and was evident in large, paired anterior ganglia, the dorsal commissure, main nerve tracts and the extensive array of small fibres that constitute the PNS. In contrast, the distribution of nerves immunoreactive to SP and PHI was less apparent, with PHI-IR occurring exclusively within the fibrous neuropile of the ganglia and in fibres of the ventral nerve cord. Results are discussed with respect to the distribution of the various neurochemical elements and their roles as putative neurotransmitters and/or regulatory molecules.     

Nervous system ofSchistosoma mansoni cercaria: Organization and fine structure

As observed by transmission electron microscopy of serially sectionedSchistosoma mansoni cercaria, the nervous system is distributed throughout the three anatomic segments of the larva-i.e., the anterior organ (oral sucker), the body (midsegment), and the tail. The central ganglion, a neuropile surrounded by cell bodies, is located in the anterior area of the body segment. It tapers anteriorly into two lobes from which a pair of anterior central nerve trunks extend longitudinally. The posterior region of the central ganglion tapers into a pair of nerve trunks (posterior central nerve trunks). Twelve peripheral nerve trunks are evenly distributed around the ganglion. Six trunks course anteriad (anterior peripheral nerve trunks) and six course posteriad (posterior peripheral nerve trunks). A pair of dorsal and ventral nerve trunks, positioned opposite each other, extend the length of the tail. All nerve trunks are unsheathed. The nervous system contains three types of vesicles. Type I vesicles average 47.66±2.57 nm in diameter, vary in electron density, and have electron-lucent peripheries. Type II vesicles have a mean diameter of 18.41±2.57 nm, are electron-lucent and are concentrated mostly in the presynaptic area of the synaptic and neuromuscular junctions. The mean diameter of Type III vesicles is 57.47±16.08 nm. They are electron-dense and are concentrated mostly in the tegumental ciliated papillac and their accompanying dendrites. Two types of synaptic junctions are present. Type1 synapse has dense material incorporated in its postsynaptic membrane, while Type2 synapse has dense material of various dimensions incorporated in its presynaptic membrane and usually in its postsynaptic membrane. Synaptic and neuromuscular junctions are similar.     

Preliminary SEM observations of the cercaria of a Sanguinicola sp. (Digenea: Sanguinicolidae)

Some data concerning the external ultrastructure of the cercariae of a Sanguinicola sp. observed with SEM are offered and the similarities and differences found when these cercariae are compared with those of Aporocotyle simplex are discussed.     

Transmission electron microscopy of sensory receptors ofEchinostoma revolutum (Froelich 1802) cercaria (Digenea: Echinostomatidae)

Nonciliate, uniciliate, and multiciliate receptors were shown by transmission electron microscopy to occur in the body tegument ofEchinostoma revolutum (Froelich 1802) cercariae. Detailed studies revealed three types of nonciliate, four types of uniciliate, and one type of multiciliate sensory endings. Most receptors were singly distributed. Only a few of them formed paired receptor complexes in three regions of the cercarial body. These receptor complexes were found to possess nociliate, uniciliate, and multiciliate sensory endings.     

The ultrastructure of the excretory bladder of the free living cercaria and metacercaria of Cercaria stunkardi Palombi, 1934 (Digenea: Opecoelidae)

Summary The ultrastructure of the excretory bladder of the free living cercaria and metacercaria of Cercaria stunkardi is described. The bladder is lined by a single layer of large nucleated cells the lateral plasma membranes of which are incomplete proximally. The structure is therefore a syncytium. Microrugae on the luminal surface of the cells suggest uptake and the occurrence of mitochondria, rough endoplasmic reticulum and ribosomes in the cytoplasm, high metabolic activity. Possible functions of the bladder epithelium and its contained secretory bodies are discussed.     

Note on the feeding habits of<Emphasis Type="Italic"> Opisthogonimus lecithonotus</Emphasis> (Trematoda,Digenea, Plagiorchiidae)

The presence of snakes blood inside the alimentary canal of the species Opisthogonimus lecithonotus (Trematoda, Digenea, Plagiorchiidae) collected from the mouth of Bothrops moojeni (Serpentes, Viperidae) is reported. The implications of this observation to the host snake are discussed.     

The nervous system ofDiplostomum pseudospathaceum Niewiadomska, (Digenea,Diplostomatidae)

The study of the nervous system and chaetotaxy ofDiplostomum pseudospathaceum Niewiadomska, cercaria was performed to verify connections between the sensory pattern and the number and arrangement of the commissures. The method of Koelle (1951) was used to detect cholinesterases in the nervous tissue and silver impregnation of the cercaria was used to reveal sensory endings on the body surface. Important differences were found in the structure of the nervous system of this cercaria in comparison with the hypothetical model proposed by Richard (1971). The differences concern the position of the central nerve ganglia, the number of the anterior nerve stems, the number of commissures and innervation of the tail. It has also been shown that particular cycles of sensillae distinguished by Richard (1971) do not correspond exactly to the commissures revealed histochemically. The similarities and differences with observations made by Grabda-Kazubska and Moczo (1981) onHaplometra cylindracea cercaria are discussed.     

Architecture of the nervous system in metacercariae of Diplostomum pseudospathaceum Niewiadomska, 1984 (Digenea)

Parasitology Research - The development of metacercariae of Diplostomum pseudospathaceum Niewiadomska, 1984 is accompanied by profound morphological transformations often characterized as...     

Characterization of the cercaria of Bucephalus polymorphus Baer, 1827 (Trematoda, Bucephalidae): chetotaxy and excretory system

We describe the excretory system and the chetotaxy of the cercaria of Bucephalus polymorphus Baer, 1827 which develops in Dreissena polymorpha (Lamellibranch, Dreissenidae) in South-East of France. We compare our observations with those realised in Poland and we discuss about the differences observed.     

Immunocytochemical demonstration of 5-hydroxytryptamine (serotonin) in the nervous system of the liver fluke,Fasciola hepatica (Trematoda,Digenea)

The localisation and distribution of 5-hydroxytryptamine (5-HT or serotonin) in the nervous system ofFasciola hepatica has been determined by an indirect immunofluorescence technique. Cell bodies and nerve fibres immunoreactive to 5-HT are present in the anterior ganglia, and the longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, similar immunoreactivity occurs in the nerve plexuses supplying the sub-tegumental muscle layers and the muscular lining of various reproductive ducts, including the ootype, uterus and cirrus pouch. The significance of these results in the light of previous studies on the role of 5-HT inF. hepatica is discussed.     

Histofluorescent and ultrastructural studies on the nervous system ofDiplostomum pseudospathaceum Niewiadomska, 1984 cercariae (Digenea)

The aminergic nervous system in cercariae ofD. pseudospathaceum was studied by fluorescence histochemistry. Green fluorescence, showing the presence of catecholamines, was present in ganglia, ventral and dorsal (the short part only) nerve trunks and also in the tail stem and furcae. The ultrastructure of various parts of the nervous system (brain, nerve trunks of body and tail stem) was also studied. Two different types of profiles were found in brain neuronal processes; six different types of vesicles were identified in nerve cells, as well as the single and shared synaptic junctions. The possible function of these structures is discussed.This work was supported by research grant No PB 1832/4/91 from the State Committee for Scientific Research     

The spatial relationship between the musculature and the 5-HT and FMRFamide immunoreactivities in cercaria,metacercaria and adult <Emphasis Type=Italic>Opisthorchis felineus</Emphasis> (Digenea)

The organisation of the neuromuscular system in cercariae, metacercariae and adult Opisthorchis felineus was studied. The patterns of nerves immunoreactive (IR) to antibodies towards serotonin (5-HT) and FMRFamide are described in relation to the musculature, stained with TRITC-conjugated phalloidin. The general organisation of the musculature in the body wall, suckers, pharynx, intestine and sphincter of the excretory pore remains the same from the larval stages to the adult worms. However, the diameter of the individual muscle fibres increases distinctly in the adult worms. The general pattern of 5-HT IR fibres in cercariae, metacercariae and adult O. felineus remains the same. Despite the large increase in body size, the number of 5-HT IR neurones remains almost the same in the cercariae and metacercariae and only a modest increase in number of neurones was observed in the adult worms. Thus the proportion of 5-HT IR neurones/body mass is greatest in the actively moving cercariae. Anti-FMRFamide stains the nervous system strongly.     

The ultrastructural characterization of the tegument ofClonorchis sinensis (Cobbold, 1875) cercaria

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