Morpho-functional characteristics of the scolex of Wardium chaunense (Cestoda: Aploparaksidae) penetrated into host intestine

The scoleces of Wardium chaunense penetrated into the intestinal wall of a snipe (Gallinago gallinago) were examined by light and transmission electron microscopy for the first time. Naturally, the scolex is characterised by a shorter length in comparison with when it is removed from the host. Ultrastructural characteristics of the main parts of the scolex, such as suckers, rostellum and rostellar sac are reported. Partial degradation of the radial muscles of the suckers is clearly recognised; this can be the result of a deep penetration of the scolex into the mucosa and subsequent loss of attachment function by suckers. The muscular walls of the rostellum and rostellar sac have a structure of the same type: an outer longitudinal layer of muscles is separated from the inner circular one with a thin basal matrix, which, also, surrounds each muscular fibre of the circular layer. Circular fibres consist of mutually perpendicular myofibrils, connected with the basal matrix by hemidesmosomes. Microtriches, covering the tegument, vary in shape in different regions of the scolex. They are absent on the apical part of the rostellum, and are slightly curved and can be considered as belonging to the fixative type on the suckers. Special sensory endings with a dense central body and without cilia are situated at the distal cytoplasm of the tegument of the suckers. Two glands, having the same syncytial structure, are disposed inside the rostellum and rostellar sac. Erythroid granules produced by the glands are released during an apocrine process into the host–parasite contact zone. Secretions of the cestode tegument in the form of vesicles and bubbles of granular material were also observed. It is suggested that the scolex attachment method of W. chaunense has the tendency of ‘anchoring’, which is an irreversible attachment used by some cestode parasites of the snipe.     

La larve d'Hymenolepis nagatyi Hilmy,, 1936 (Cestoda,Cyclophyllidea)

Résumé L'auteur signale Hymenolepis nagatyi Hilmy, 1936 en Côte d'Ivoire et décrit sa larve cysticercoïde obtenue expériementalement chez Tenebrio molitor L. Le développement particulier du rostre est décrit et illustré.

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The larva of hymenolepis nagatyi Hilmy, 1936 (Cestoda, Cyclophyllidea)

Summary Hymenolepis nagatyi has been described from shrews from Liberia and from the former Belgian Congo. It has an enormous scolex which is inserted beneath the mucous lining of the gut. This species has been found on three occasions in shrews Crocidura sp. from the Ivory Coast and the larva has been obtained experimentally.Gravid proglottids were fed to meal beetles Tenebrio molitor and from 1–126 cysticercoids were recovered after 18 days and being infective after 24 days.The interesting fact is that the scolex is perfectly normal although the rostellar hooks, of which there are 84–95, are very closely set. When placed in contact with the intestinal mucosa of a shrew, the larvae evaginate in about 10–15 min. In the presence of mucosa from a rodent Mastomys erythroleucus, evagination does not take place and all movement ceases within an hour. When cysticercoids were fed to Crocidura flavescens spurelli, one of these, four days later, had a young worm attached to the mucosa. The growing scolex is described and the presence of glandular cells in the rostellum noted. The secretion of the latter appear to destroy the mucosa and enables the rostellum to penetrate and to grow to its full size.

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Zusammenfassung Der Verfasser berichtet über das Vorkommen von Hymenolepis nagatyi Hilmy, 1936 an der Elfenbeinküste und beschreibt die zugehörige Larve (Cysticercoid), die er experimentell bei Tenebrio molitor L. erhielt. Die Entwicklung speziell des Rostrums wird beschrieben und illustriert.

     

Redescription of Diporotaenia colymbi Spasskaya, Spassky et Borgarenko, 1971 (Cestoda, Cyclophyllidea, Schistotaeniidae) and amended diagnoses of Diporotaenia Spasskaya, Spassky et Borgarenko, 1971 and Diporotaeniinae Ryzhikov et Tolkacheva, 1975

Diporotaenia colymbi Spasskaya, Spassky et Borgarenko, 1971 (Cestoda, Cyclophyllidea, Schistotaeniidae) is redescribed from Tachybaptus ruficollis (L.) in Turkmenistan. An amended generic diagnosis of Diporotaenia Spasskaya, Spassky et Borgarenko, 1971 is proposed. The taxonomy of Schistotaeniidae Johri, 1959 and the generic composition of its subfamilies, Schistotaeniinae Johri, 1959 and Diporotaeniinae Ryzhikov et Tolkacheva, 1975, are discussed. The genera Ryjikovilepis Gulyaev et Tolkacheva, 1987, Isezhia Gulyaev et Konyaev, 2004, Mircia Konyaev et Gulyaev, 2006 and Decarabia Konyaev et Gulyaev, 2005 are considered as members of the subfamily Diporotaeniinae. An amended diagnosis of the latter subfamily is proposed.     

Etude ultrastructurale de la larve de Anomotaenia constricta (Cestoda,Cyclophyllidea)

Résumé La larve de A. constricta, obtenue expérimentalement dans l'hémocoele d'un Coléoptère Pimelia sulcata évolue à l'intérieur d'une enveloppe larvaire. Entre le cysticercoïde et l'enveloppe larvaire, le cercomère se fragmente en follicules pluricellulaires qui baignent dans une substance amorphe.Le tégument de ces follicules est bordé de microvillosités en «doigt de gant» identiques à celles qui couvrent le tégument des jeunes stades, alors que le tégument de la paroi cystique externe est surmonté de microtriches incomplètement différenciées, l'épine terminale faisant défaut. Enfin, le tégument de la paroi cystique interne et celui du scolex présentent des microtriches typiques. La différenciation du tégument des différentes formations est liée à l'évolution du cysticercoïde.Les tests histochimiques révèlent que la quantité de glycogène contenu dans le cercomère est faible, comparativement à ce que l'on trouve dans la paroi du cysticercoïde d'une part et dans la paroi du métacestode, où il est le plus abondant, d'autre part.On discute le rôle des différentes formations larvaires dans la protection et la nutrition du métacestode.Enfin, on compare la structure du cysticercoïde de A. constricta à celle de Tatria octacantha, étudiée par Rees (1973).

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Ultrastructural study of larval Anomotaenia constricta (Cestoda, Cyclophyllidea)

Summary The metacestode of Anomotaenia constricta, from the haemocoele of the beetle Pimelia sulcata is enclosed in a capsule and consists in a cysticercoid surrounded by follicles which proceed from the cercomer (fig. 1). The follicles are embedded in an amorph substance. The microtriches which cover the tegument are found to be of three different forms depending on their location.The tegument of the cercomer bears fingerlike extensions (fig. 5) resembling that found in the tegument of the youngest stages (fig. 4), whereas the tegument of the extern cystic wall is covered by knoblike projections (fig. 12) which resemble the fully developed projections but without the spike portion. The outer surface of the scolex bears projections of the same type as those of adult tapeworms (fig. 10).The differentiation of the tegument from the different parts of the metacestode is in relation with the differentiation of the cysticercoid.The histochemical tests show that the amount of glycogen in the cercomer is slight, comparatively to those in the cysticercoid wall and in the scolex.We discuss the role of the different larval formations in the protection and the nutrition of the metacestode.We compare the cysticercoid structures of A. constricta and Tatria octacantha (fig. 15A et B).

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Avec l'aide technique de Mademoiselle Parpère, Technicienne au Laboratoire d'Histologie et d'Embryologie, Section Microscopie Electronique et de Madame Euzet, Technicienne C.N.R.S. au Laboratoire de Parasitologie Comparée.     

Neuropeptide F-immunoreactivity in the tetrathyridium ofMesocestoides corti (Cestoda: Cyclophyllidea)

The distribution pattern and subcellular localisation of neuropeptide F (NPF) immunoreactivity (IR) in the tetrathyridium stage ofMesocestoides corti were investigated by whole-mount immunocytochemistry in conjunction with confocal scanning laser microscopy (CSLM) and by immunoelectron microscopy using immunogold labeling. Using an antiserum directed to the C-terminal decapeptide amide (residues 30–39) of synthetic NPF (Moniezia expansa), CSLM revealed NPF-IR throughout the central and peripheral nervous systems of parental and dividing tetrathyridia. Ultrastructurally, gold labeling of NPF-IR was confined to the contents of the smaller of the two sizes of electron-dense neuronal vesicle identified.     

Serotoninergic and peptidergic nerve elements in the protoscolex ofEchinococcus granulosus (Cestoda,Cyclophyllidea)

The localisation and distribution of 5-hydroxytryptamine (5-HT, or serotonin) and neuropeptides in the nervous system of the protoscolex of the hydatid organismEchinococcus granulosus were determined by an indirect immunofluorescence technique. Nerve-cell bodies immunoreactive for 5-HT occurred in the lateral ganglia and in association with the lateral longitudinal nerve cords. 5-HT immunostaining was also evident in the central nerve ring, in the rostellar nerves and in the nerve plexus innervating the suckers. Of the antisera used to screen the protoscolex for neuropeptide immunoreactivity (IR), immunostaining was obtained with those raised against pancreatic polypeptide (PP), peptide YY (PYY), substance P (SP), peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP). The most extensive pattern of IR occurred with antisera to PP and PYY. Immunoreactive nerve elements were evident in the lateral ganglia, central nerve ring, rostellar nerves, rostellar ganglia, sucker plexus and longitudinal nerve cords. The distribution of SP-, PHI- and VIP-IRs was more restricted: SP-IR occurred in the lateral ganglia and sucker nerves, whilst PHI- and VIP-immunoreactive nerve elements were associated with the lateral longitudinal nerve cords. Protoscoleces cultured in vitro for 29 days were also examined and neuroanatomical changes noted. A greater development of the longitudinal nerve cords and their cross-connectives in the body of the worm was evident, and a group of nerve cells were seen to develop at the posterior end of the main lateral nerve cords.     

Spermiogenesis and sperm ultrastructure of Valipora mutabilis Linton, 1927 (Cestoda, Cyclophyllidea, Gryporhynchidae)

This is the first ultrastructural study of the spermiogenesis and the mature spermatozoon of a cyclophyllidean cestode of the family Gryporhynchidae. The spermiogenesis of Valipora mutabilis begins with the formation of a differentiation zone delimited by arching membranes and containing two centrioles. One of the centrioles develops an axoneme that grows directly into the cytoplasmic protrusion. The other centriole remains situated in a cytoplasmic bud and is subsequently aborted (type IV of cestode spermiogenesis). The mature spermatozoon of V. mutabilis is a filiform cell, tapered at both extremities and lacks mitochondria. The anterior extremity is characterised by the presence of an apical cone and a single helicoidal crested body. The axoneme is of 9 + ‘1’ trepaxonematan pattern, with a periaxonemal sheath. The cortical microtubules are twisted at an angle of about 45° to the spermatozoon axis. The nucleus is electron dense and spirally coiled around the axoneme. The cytoplasm is electron lucent and contains numerous granules of electron-dense material. In contrast to a recent opinion for close phylogenetic relationships, these ultrastructural data demonstrate the distant position between gryporhynchids and the family Taeniidae. The most similar pattern in the ultrastructure of the spermiogenesis and the mature spermatozoon has been described for dilepidids, some hymenolepidids and some anoplocephalids.     

The effect of cortisone acetate on the metabolism of Hymenolepis microstoma (Cestoda: Cyclophyllidea)

Summary Hymenolepis microstoma grown in mice, treated with 1.25 mg cortisone acetate every second day, are heavier and have a significantly higher glycogen content than those in control mice. The dry/wet weight ratio and protein content however are unaffected. It is suggested that the increase in glycogen reserve and weight in H. microstoma from cortisone-treated mice is due to an immunosuppressive effect and better nutritional environment rather than hormonal action. Inclusion of 0.1 mg of cortisone per 100 ml of culture medium produces no change in worm weight in vitro.Single worm infections result in 100% recovery, but 30 worm infections provoke a rejection process which can be suppressed partially by administration of cortisone acetate. Present address: Vakgroep Dierkunde, Landbouwhogeschool, Ritzema Bosweg 32A, Wageningen, The Netherlands. The senior author acknowledges gratefully a fellowship from the University of Gent.     

Phylogeny of hymenolepidid cestodes (Cestoda: Cyclophyllidea) from mammalian hosts based on partial 28S rDNA,with focus on parasites from shrews

Parasitology Research - The aims of the study are to enrich the partial 28S rDNA dataset for hymenolepidids by adding new sequences for species parasitic in the genera Sorex, Neomys and Crocidura...     

Ultrastructure of spermiogenesis and mature spermatozoon of Angularella beema (Clerc, 1906) (Cestoda, Cyclophyllidea, Dilepididae)

The ultrastructure of the spermiogenesis of a dilepidid cestode species is described for the first time. The spermiogenesis of Angularella beema is characterised by absence of both flagellar rotation and proximodistal fusion. The differentiation zone is surrounded by cortical microtubules and is delimited by a ring of arching membranes. It contains two centrioles, one of which develops the axoneme that grows directly into the elongating cytoplasmic protrusion. This pattern of spermiogenesis was described as the Type IV spermiogenesis of cestodes. Among cestodes, similar pattern of spermiogenesis is known in the family Hymenolepididae and in some representatives of the family Anoplocephalidae. The mature spermatozoon of A. beema consists of five regions differing in their ultrastructural characteristics. It is characterised by the presence of cortical microtubules (spirally arranged at angle of 30–40° to the spermatozoon axis) and a single crested body. There is a periaxonemal sheath in certain parts of the spermatozoon as well as glycogen-like granules between the periaxonemal sheath and the cortical microtubules. The comparisons of the mature spermatozoon of A. beema with those of other two dilepidid species (Dilepis undula and Molluscotaenia crassiscolex) demonstrate some variation within the family: presence of periaxonemal sheath in A. beema and D. undula and its absence in M. crassiscolex; presence of electron-dense rods in D. undula and their absence in A. beema.     

The occurrence of the cysticercoids ofAcanthocirrus retrirostris (Krabbe 1869) Baer 1956 (Cyclophyllidea,Dilepididae) and the metacercariae ofMaritrema gratiosum Nicoll 1907 (Digenea,Microphallidae) in the barnacle,Balanus balanoides (L.), on the coast of Yorkshire,England

A total of 1806 specimens of barnacles,Balanus balanoides, collected from the Yorkshire coast of England was examined for encysted helminth larvae. Twelve (0.7%) barnacles were infected with the hitherto unknown cysticercoid ofAcanthocirrus retrirostris (Krabbe, 1869) (Cyclophyllidea, Dilepididae). A total of 16 cysticercoids was found and their essential features are described. Also, 309 (17%) barnacles were infected with metacercariae ofMaritrema gratiosum Nicoll, 1907 (Digenea, Microphallidae). The mean intensity ofMaritrema gratiosum in infected barnacles was 1.4, and the frequency distribution of number of metacercarial cysts per barnacle agreed closely with a negative binomial frequency distribution. The ecological relationships of the cysticercoids and metacercariae with barnacles, the avian definitive hosts and the environment are discussed.     

Ultrastructure of the spermatozoon of the bank vole tapeworm, Paranoplocephala omphalodes (Cestoda, Cyclophyllidea, Anoplocephalidae)

The mature Paranoplocephala omphalodes spermatozoon is filiform, tapered at both ends and lacks mitochondria. Its anterior extremity exhibits an apical cone of electron-dense material measuring about 900 nm in length and 200 nm in width, and two crested-like bodies. The cortical microtubules follow a 25–35° helicoidal path along their whole length, except at the posterior extremity where they become parallel to the spermatozoon axis. They are arranged in a single or two fields which may cover each other partially. The axoneme, of the 9+“1” pattern of the Trepaxonemata, lacks a peri-axonemal sheath and does not reach the extremity of the spermatozoon. The nucleus is a compact and irregular cord coiled in a spiral around the axoneme. Moreover, we report for the first time a nucleus in the spermatozoon of a Cyclophyllidea species which reaches beyond the axonemal posterior extremity. The cytoplasm, depending on the level where the section is cut, is slightly electron dense or electron lucent and contains numerous small electron-dense granules in regions III–V. In the posterior spermatozoon extremity, granular material is replaced by a terminal and compact electron-dense material. Received: 1 June 1997 / Accepted: 20 September 1997     

Occurrence of Echinococcus multilocularis (Cestoda, Taeniidae) in red foxes (Vulpes vulpes) from Western Ukraine

Echinococcus multilocularis was found for the first time in red foxes in the L’vivska and Volynska regions (Western Ukraine). Prevalence was 36% and intensity was 11–731 parasites. The material was identified as E. multilocularis on morphological characters. It is presumed that this infection of foxes with E. multilocularis occurred locally and, probably, can be considered as a consequence of the expansion of the range of the parasite.     

The common vole,Microtus arvalis pall. as intermediate host ofMesocestoides (Cestoda) in Germany

Tetrathyridia ofMesocestoides leptothylacus Loos-Frank, 1980 were found in 1.4% of 513 common voles (Microtus arvalis) in a district of Southwest Germany where foxes (Vulpes vulpes) are frequently infected with this tapeworm. The tetrathyridia measured 1 to 1.5 mm in length and 0.5 to 1 mm in width. When injected intraperitoneally into white mice, jirds, or common voles, the tetrathyridia did not multiply. Cats fed with the larvae shed proglottids from the 21^st day onwards. In one experimentally infected silver-fox proglottids were passed from day 12 onwards. One human subject infected twice with tetrathyridia ofM. leptothylacus, did not develop patent infections. One common vole from another district contained tetrathyridia of aMesocestoides species, which is rarely found in indigenous foxes and which is characterized by a broad-oval cirrus pouch with a much convoluted cirrus.Dedicated to the 70th birthday of Professor Piekarski     

Ultrastructure of spermiogenesis and the spermatozoon of Sudarikovina taterae (Cestoda, Cyclophyllidea, Anoplocephalidae) intestinal parasite of Tatera gambiana (Rodentia, Gerbillidae)

The young spermatid of Sudarikovina taterae exhibits a nucleus with a partially condensed chromatin and a differentiation zone, bordered by cortical microtubules, delimited at the front by arched membranes and containing two centrioles. The latter are parallel to one another and linked together at their bases by electron-dense material. During spermiogenesis, one of the centrioles gives rise to a flagellum whereas the other disappears. Crested-like bodies lie outside the cortical microtubules and the nucleus migrates in the spermatid along the axoneme. At the end of spermiogenesis, the ring of arched membranes constricts and the old spermatid becomes detached from the residual cytoplasm. The S. taterae mature spermatozoon is filiform and tapered at both extremities. It exhibits an apical cone of electron-dense material and seven crested-like bodies 50 to 100 nm thick. The cortical microtubules run along the whole length of the spermatozoon. They are spiralized at their anterior extremities and straight over the rest of their length. The nucleus is a fine compact cord interposed between the axoneme and the cortical microtubules. The cytoplasm is slightly electron-dense in regions I and II of the gamete. In regions III, IV and V, it contains fine electron-dense granulations and patches of electron-lucent material. An electron-dense material located both between and under centrioles has not been observed before in a platyhelminth. Similarly, distinctive ultrastructural characters between centrioles and seven crested-like bodies have not been previously described in a cestode. Moreover, we report for the first time the existence of cortical microtubules spiralized only at their anterior extremities in a cestode from a mammal.     

A serine proteinase in the penetration glands of the hexacanths of Hymenolepis diminuta (Cestoda, Cyclophyllidea)

 Histochemically demonstrable activity of a serine proteinase was detected in the penetration glands of Hymenolepis diminuta hexacanths. At the optimal pH of 8.4 the enzyme hydrolyzed N-blocked l-aminoacyl- and N-blocked l-peptidyl-naphthylamides bearing l-arginine at the P₁ subsite. The proteinase did not require either Ca²⁺ or Mg²⁺ for its activity and was insensitive to 1 mM EGTA and 1 mM EDTA. Organic fluorophosphates inhibited it, whereas thiol-blocking compounds did not. At operative pH values of 4.8 and 3.8 generated during electrophoresis in a stacking and a resolving gel, respectively, the proteinase migrated toward the cathode. When examined for proteolytic activity at the optimal pH of 8.4, the separated enzyme produced a single band of gelatinolysis in a gelatin-containing polyacrylamide gel. During in vitro maintenance of the hexacanths, the secretion from their penetration glands formed a mucous cyst surrounding the individual larvae. The cyst was resistant to and protected the hexacanths from the proteolytic activity of trypsin, papain, and proteinases extracted from the gut of the beetle Tenebrio molitor (the host). Hexacanths extracted from the hemocoel of T. molitor at 24 and 48 h after infection were surrounded by similar mucous cysts. Consequently, roles in penetration and protection for the secretion from the penetration glands are postulated. Received: 18 January 1995 / Accepted: 20 May 1995