[Show abstract][Hide abstract] ABSTRACT: The vitellarium of the invasive caryophyllidean tapeworm Khawia sinensis Hsü, 1935 from carp Cyprinus carpio L. was examined by means of transmission electron microscopy and cytochemical staining for glycogen with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP). A vitellarium consists of numerous follicles of irregular size that are interconnected by a net of vitelline ducts. Vitelline follicles are composed of vitelline cells at various stages of development that are interconnected by interstitial tissue. Vitelline follicles are surrounded by a cytoplasmic sheath associated with an intercellular matrix. Extensive development of the granular endoplasmic reticulum and Golgi complexes are both involved in the production of shell globules/shell globule clusters and characterise cytodifferentiation of vitellocytes. Nuclear and nucleolar transformation lead to the formation and storage of intranuclear glycogen, a feature specific for the Caryophyllidea. Newly observed within the mature vitellocytes of Khawia sp. is the presence of lamellar bodies and a few lipid droplets. These cytoplasmic inclusions first occur in the mature cells within the follicles and persist in the vitelline cells within vitelloducts and intrauterine eggs. Two types of lamellar bodies are detected: regular lamellar-structured body and irregular lamellar-structured body. None of the lamellar bodies are membrane bound. Results of the present study indicate that the formation of lamellar bodies may be closely related to the endoplasmic reticulum or shell globule clusters. Some of the shell globule clusters are transformed into lamellar body clusters. Ultrastructural features of vitellocytes in K. sinensis are compared with those of other monopleuroid, polypleuroid, and strobilated cestodes.
No preview · Article · Jun 2013 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: Reinvestigation of vitellogenesis in the caryophyllidean cestode Caryophyllaeus laticeps (Pallas, 1781) has been performed using light microscope (LM) and transmission electron microscopy (TEM), and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) for glycogen. Vitellogenesis is generally similar to that reported in the past, however, some new observations were made. The present study reveals the first evidence of: (i) interstitial tissue in the vitelline follicles, (ii) lipid droplets in maturing and mature vitellocytes from vitelline follicles, and (iii) lamellar bodies in vitellocytes from the vitelloduct in C. laticeps. Projections of interstitial tissue surround each vitellocyte and the follicle periphery. The perinuclear cytoplasm of the interstitial tissue contains granular endoplasmic reticulum and vesicles of various size and density. Cytoplasmic osmiophobic lipid droplets and lamellar bodies, previously believed to be absent in most caryophyllid cestodes, are readily apparent in vitellocytes of C. laticeps. The origin and presumed function of these inclusions are discussed. On the other hand, the formation and storage of massive amounts of glycogen in the nucleus and large amounts in the cytoplasm of mature vitelline cells are similar to the condition found in other caryophyllids. Results are compared and contrasted with previous studies on vitellogenesis in other monopleuroid cestodes (Amphilinidea and Gyrocotylidea) as well as polypleuroid cestodes (Spathebothriidea) and the remaining strobilated Eucestoda.
[Show abstract][Hide abstract] ABSTRACT: Vitellogenesis in the caryophyllidean tapeworm Archigetes sieboldi Leuckart, 1878, from carp Cyprinus carpio L. in Slovakia, has been examined using transmission electron microscopy and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) for glycogen. Vitelline follicles extend in two lateral bands in the medullary parenchyma along both sides of the monozoic body. They are surrounded by an external basal lamina and contain vitellocytes and an interstitial tissue. The general pattern of vitellogenesis is essentially like that of other caryophyllideans. It involves four stages: immature, early maturing, advanced maturing cells and mature vitellocytes. During vitellogenesis, a continuous increase in cell volume is accompanied by an extensive development of cell components engaged in shell globule formation, e.g. granular endoplasmic reticulum and Golgi. Shell globule clusters are membrane-bound. Nuclear and nucleolar transformation are associated with formation and storage of large amounts of intranuclear glycogen, a very specific feature of the Caryophyllidea. For the first time, (a) additional vitelline material in Archigetes is represented by lamellar bodies and (b) lipid droplets are described in the mature vitellocytes from vitelline follicles and vitelloduct of the Caryophyllidea. Our results indicate that there may be a double origin of lamellar bodies: either from the endoplasmic reticulum or through transformation of shell globule/shell globule clusters. Lamellar body clusters and some single lamellar bodies appear to have a membrane. Other ultrastructural features of vitellogenesis and/or vitellocyte in A. sieboldi from its vertebrate (fish) and invertebrate (oligochaete) hosts are briefly compared and contrasted with those in other caryophyllideans and/or Neodermata.
No preview · Article · Dec 2012 · Histology and histopathology
[Show abstract][Hide abstract] ABSTRACT: Tapeworms (Cestoda, Platyhelminthes) are a highly diversified group of parasites that can have significant veterinary importance as well as medical impact as disease agents of human alveococcosis, hydatidosis, taeniosis/cysticercosis/neurocysticercosis, hymenolepidosis or diphyllobothriasis. Because of their great diversity, there has been keen interest in their phylogenetic relationships to other obligate parasitic platyhelminthes, as well as within the group itself. Recent phylogenetic analyses of cestodes, however, have focused on morphological, molecular, life cycle, embryology and host-specificity features and conspicuously omitted inclusion of karyological data. Here we review the literature from 1907 to 2010 and the current status of knowledge of the chromosomes and cytogenetics within all of the cestode orders and place it within an evolutionary perspective. Karyological data are discussed and tabulated for 115 species from nine eucestode orders with ideograms of 46 species, and a comparison of cytogenetic patterns between acetabulate and bothriate cestode lineages is made. Attention is drawn to gaps in our knowledge for seven remaining orders and cestodarian groups Gyrocotylidea and Amphilinidea. Among the cytogenetic aspects covered are: chromosome number, triploidy, classical karyotype cytogenetics (banding patterns, karyotype asymmetry, secondary constrictions), as well as advanced karyotype techniques allowing location of genes on chromosomes by fluorescence in situ hybridization. We demonstrate that further progress in cestode karyosystematics rests with new molecular approaches and the application of advanced cytogenetic markers facilitating intimate karyotype analysis.
Full-text · Article · Dec 2011 · Advances in Parasitology
[Show abstract][Hide abstract] ABSTRACT: Intrauterine embryonic development in the caryophyllidean tapeworm Khawia sinensis has been investigated using transmission electron microscopy and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for glycogen. Contrary to previous light microscopy findings that reported the release of non-embryonated eggs of K. sinenesis to the external environment, the present study documents various stages of embryonation (ovoviviparity) within the intrauterine eggs of this cestode. At the initial stage of embryonic development, each fertilised oocyte is accompanied by several vitellocytes that become enclosed within the operculate, electrondense shell. Cleavage divisions result in formation of blastomeres (up to about 24 cells) of various sizes. Mitotic divisions and apparent rosette arrangment of the blastomeres, the latter atypical within the Eucestoda, are observed for the first time in the intrauterine eggs of K. sinenesis. The early embryo enclosed within the electrondense shell is surrounded by a thin membraneous layer which in some enlarged regions shows presence of nuclei. Simultaneously to multiplication and differentiation, some of the blastomeres undergo deterioration. A progressive degeneration of the vitellocytes within eggs provides nutritive reserves, including lipids, for the developing embryo. The possible significance of this atypical timing of the intrauterine embryonic development to (1) the ecology of K. sinensis and that of a recent introduction of another invasive tapeworm, the caryophyllidean Atractolytocestus huronensis Anthony, 1958 to Europe; and (2) the affiliation of caryophyllideans with other lower cestodes, are discussed.
Full-text · Article · Sep 2011 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: The first description of vitellogenesis in the Diphyllidea is presented in this paper. Though the type of vitellogenesis and
mature vitellocyte in Echinobothrium euterpes appear to be unique among the Eucestoda, however, they somewhat resemble that observed in the two orders of the lower cestodes,
Tetraphyllidea and Proteocephalidea. Vitellocyte maturation is characterized by: (1) an increase in cell volume; (2) extensive
development of short, parallel, frequently concentric cisternae of GER that produce dense proteinaceous granules; (3) development
of Golgi complexes engaged in packaging this material; (4) progressive formation of saturated lipid droplets; their continuous
enlargement and fusion; (5) formation of small accumulations of glycogen particles scattered between and among lipid droplets
in the cytoplasm of maturing vitellocytes; (6) concentration of dense proteinaceous granules in the peripheral layer of cytoplasm,
around the cell plasma membrane; and (7) vacuolization of cytoplasm of mature vitellocytes accompanied by a rapid increase
in its volume. A new, unreported type of dense proteinaceous granules, situated around the limiting plasma membranes of mature
vitellocytes, is described. Vitellogenesis evidently differs from that with typical shell-globules and shell-globule clusters
previously reported in other taxa of lower cestodes. Cytochemical staining with periodic acidthiosemicarbazide-silver proteinate
for glycogen indicates a strongly positive reaction for glycogen particles between and around large unsaturated lipid droplets
of the maturing and mature vitellocytes. Some hypotheses concerning the interrelationship between this pattern of vitellogenesis,
possible mode of egg formation, embryonic development and diphyllidean life cycle, and their phylogenetic implications are
drawn and discussed.
–vitellogenesis–ultrastructure–cytochemistry–dense proteinaceous granules–saturated lipids–glycogen
Preview · Article · Jun 2011 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: Ultrastructural and cytochemical characteristics of GER-bodies observed in the vitellocyte cytoplasm of the intrauterine eggs
of the caryophyllidean cestode Wenyonia virilis are described. In this species GER-bodies were observed only in the cytoplasm of vitellocytes, surrounded by a newly formed
egg-shell. They are composed of spherical areas of condensed, electron-dense cytoplasm which contains concentrically arranged
parallel lamellae of granular endoplasmic reticulum (GER), forming characteristic balls of different sizes. Each GER-body
is surrounded by numerous free ribosomes, polyribosomes, α-glycogen rosettes and large mitochondria. Results of cytochemical
analysis by means of PATSC-SP test for polysaccharides indicated that glycogen is absent within the GER-bodies, however, a
strongly positive reaction was observed only in large aggregations of α-glycogen rosettes and β-glycogen particles, localised
usually near GER-bodies.
Full-text · Article · Mar 2011 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: The histology of the scolex and neck region was examined in adults of the caryophyllidean tapeworms Glaridacris laruei and Glaridacris catostomi, parasites of the white sucker, Catostomus commersoni (Lacépède). Several distinct cell types were identified in the parenchyma including tegumental cells, flame cells, longitudinal muscle cells (myoblasts), transverse and dorsoventral muscle cells, parenchyma cells, epithelioid cells, and cells associated with the calcareous corpuscles. The proliferative zone of germinative cells reported for strobilate tapeworms was not found in these species. Faserzellen, or neck cells, which consisted of a deeply staining mass of cells, were found in the medullary parenchyma of the neck. Histochemical tests revealed that the cytoplasm of the Faserzellen was rich in RNA and protein, but alkaline and acid phosphatase activity were not detected. The arrangement of musculature in the scolex was examined; muscles associated with the attachment organs of G. laruei appear more developed compared with those of G. catostomi. Measurements of the various cells and their characteristic staining properties are presented in tabular form.
No preview · Article · Feb 2011 · Canadian Journal of Zoology
[Show abstract][Hide abstract] ABSTRACT: Ultrastructural evidence for early intraurerine embryonic development of Wenyonia virilis is presented. At the initial stage of egg formation, the fertilized oocyte or ovum is surrounded by numerous vitellocytes and newly formed eggshell. Individual vitellocytes undergo progressive fusion into a vitelline syncytium. During cleavage divisions, three types of blastomeres are formed: macromeres, mesomeres and micromeres. Two large macromeres contain a large nucleus with spherical nucleolus and numerous small heterochromatin islands dispersed in moderately electron-dense nucleoplasm. The granular cytoplasm shows a few large mitochondria. Medium-sized mesomeres contain a spherical nucleus with numerous heterochromatin islands, adjacent to the nuclear envelope, and a prominent electron-dense nucleolus. Their nuclei are embedded in granular cytoplasm with a few large and numerous small mitochondria and Golgi complexes. The small micromeres are characterized by presence of spherical nucleoli with large areas of highly condensed heterochromatin and a few islands of granular electron-lucent nucleoplasm. Their granular cytoplasm shows a few small lipid droplets and several spherical mitochondria. Majority of micromeres give rise to the hexacanth but many of them also undergo degeneration or apoptosis. Both mesomeres and macromeres are engaged in the formation of the oncospheral envelopes. The outer envelope is formed by a fusion of two macromeres whereas the inner envelope originates from a fusion of mesomeres. The intrauterine eggs of W virilis usually contain an embryo at the early preoncopheral phase of development and possesses three primary envelopes: (1) thick eggshell; (2) thin cytoplasmic layer of the outer envelope and (3) inner envelope. Based on embryonic development, egg type and life-cycle characteristics, caryophyllideans tend to show closer affinities to spathebothriideans than to the former pseudophyllideans.
Full-text · Article · Dec 2010 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: A comparative study of the scoleces of caryophyllidean tapeworms (Cestoda: Caryophyllidea), parasitic in cypriniform fishes in the Palaearctic Region, was carried out using light and scanning electron microscopy. Three-dimensional pictures of the scoleces of 18 species of caryophyllidean cestodes of the Capingentidae (1 species), Caryophyllaeidae (7) and Lytocestidae (10), and outlines of the scoleces and anterior extent of the testes and vitelline follicles of 19 Palaearctic taxa were documented. Both species of Atractolytocestus Anthony, 1957 possess a bulboacuminate scolex, whereas species of Archigetes Leuckart, 1876 have fossate scoleces of the bothrioloculodiscate type, with loculi, bothrium-like depressions and an apical disc. Breviscolex orientalis Kulakovskaya, 1962, the only member of the Capingentidae, has a cuneiform scolex, as do both taxa of the lytocestid genus Caryophyllaeides Nybelin, 1922. The scoleces of two species of Caryophyllaeus Gmelin, 1790 are flabellate, whereas that of the congeneric C. fimbriceps Annenkova-Chlopina, 1919 is cuneicrispitate. Khawia Hsü, 1935, the most specious Palaearctic genus, with seven taxa that we consider to be valid, has the highest diversity in scolex morphology: semi-bulbate, flabellate, cuneiform, cuneifimbriate, truncated cuneiform-flabellate and festoon-like. Species of Monobothrium Nybelin, 1922 have either a digitiform scolex with widened posterior part or cuneiform, with lateral auricular extensions. Paracaryophyllaeus gotoi (Motomura, 1927) is characteristic in its possessing a bulbate scolex, whereas Paraglaridacris limnodrili (Yamaguti, 1934) has a fossate scolex of the bulboloculate type with bothrium-like depressions and feebly developed lateral loculi. Anterior extent of the testes and vitelline follicles and their mutual position show a somewhat higher variability than scolex shape, with intraspecific variation in some taxa, such as Atractolytocestus sagittatus (Kulakovskaya et Akhmerov, 1965), B. orientalis, Khawia armeniaca (Cholodkovsky, 1915) and K. sinensis Hsii, 1935. Based on scolex morphology and relative position of the anterior testes and vitelline follicles, a key is provided to facilitate the routine identification of 20 Palaearctic caryophyllidean taxa.
Full-text · Article · Mar 2010 · Folia parasitologica
[Show abstract][Hide abstract] ABSTRACT: Vitellogenesis in Wenyonia virilis was examined by transmission electron microscopy (TEM), including the cytochemical detection of glycogen at the ultrastructural
level with the periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) technique. Mature vitelline follicles have cells
in various stages of development, progressing from immature cells of gonial type near the periphery of the follicle to maturing
and mature vitellocytes towards the centre. Maturation is characterized by: (1) increase in cell volume; (2) increase in nuclear
surface area restoring the N/C (nucleo-cytoplasmic) ratio; (3) nucleolar transformation; (4) extensive development of parallel
cisternae of GER, the shell-protein producing units; (5) development of Golgi complexes, engaged in shell-granule/shell-globule
formation and packaging; (6) synthesis and storage of glycogen in the cytoplasm; (7) simultaneous, independent formation and
storage of intranuclear glycogen; (8) continuous fusion of small shell-granules into larger shell-globules and fusion of these
into large shell-globule clusters with a progressive increase in the number and size of the latter; and (9) disintegration
of GER in the medial layer of vitellocyte cytoplasm, degenerative changes and accumulation of glycogen and shell-globule clusters
within the cytoplasm. The functional significance of numerous shell-globule clusters and the relatively small amount of nuclear
and cytoplasmic glycogen is analysed. Unlike vitellogenesis of other caryophyllids, the nuclear glycogen of mature vitellocytes
in W. virilis is randomly dispersed in the nucleoplasm and never forms a high central accumulation, the so-called “nuclear vacuole”. The
nutritive function of vitellocytes appears greatly reduced in W. virilis, a fact perhaps related to the intrauterine development of the early embryos. The ultrastructure of vitellogenesis in W. virilis is compared with that in other lower cestodes, both monozoic and polyzoic. Conclusions concerning interrelationships of the
vitellogenesis pattern of the ultrastructural cytochemistry of mature vitellocytes of W. virilis to intrauterine embryonation, absence of uterine glands and an extensive uterus characteristic for this species, are drawn
Full-text · Article · Jun 2009 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: Transmission (TEM) and scanning (SEM) electron microscope methods were used to study the fine structure of the cirrus, cirrus sac, internal seminal vesicle, ejaculatory duct, prostate glands and cirrus armature of Echinophallus wageneri (Monticelli, 1890) and Paraechinophallus japonicus (Yamaguti, 1934) (Bothriocephallidea: Echinophallidae). The cirrus sac of these species has two unique ultrastructural features: a thick wall with two bands of muscles and prominent, rooted hard structures. Rare traits echinophallids share with diphyllobothriideans are microtriches on the ejaculatory duct and with spathebothriideans, well-developed unicellular prostate glands outside the cirrus sac. Because there is a similarity of cirrus armature and rostellar hooks in having a tegumental localisation and in having a heterogenous structure of the blade and root, a cortex, a central pulp region and a recurved apex, these structures are named "modified hooks" instead of spines. They also have a spiral arrangement; no base plate was observed. True spines, as found in trematodes, are between the surface and basal plasma membrane of the external syncytial layer of the tegument, rest on the basal plasma membrane of the distal epithelial cytoplasm, show a homogeneous electron-dark crystalline appearance and are covered by the surface plasma membrane. Aside from the characteristic hooks on the scolex of various cestodes, we see no evidence that would preclude the development of still other specialised structures, such as these modified hooks, from microtriches. In spite of the absence of studies on the development of modified hooks from the cirrus of echinophallids and/or its consideration as derived from microtriches, we assume that like microtriches, formation of modified hooks is from tegumental bodies and therefore they are derivative structures of the cestode tegument.
No preview · Article · Sep 2008 · International journal for parasitology
[Show abstract][Hide abstract] ABSTRACT: Phylogenetic relationships of all genera of the order Caryophyllidea, possibly the earliest branching group of true tapeworms (Platyhelminthes: Eucestoda) and the only one that is monozoic, have been assessed for the first time. Results of this cladistic analysis, inferred from 30 unweighted morphological characters, are only partly congruent with the existing classification, which consists of four families based on the position of the inner longitudinal muscles in relation to the internal genital organs. Whereas all but five genera of the Caryophyllaeidae form a monophyletic clade, members of the Capingentidae are split, occurring within six unrelated groups. The Lytocestidae is also paraphyletic, as some genera appear in four unrelated clades. Archigetes appears in a derived clade, indicating that its direct (monoxenous) life-cycle involving only tubificid oligochaetes is secondarily derived and not plesiomorphic among the Eucestoda, as postulated by some authors.
Full-text · Article · Jun 2008 · Systematic Parasitology
[Show abstract][Hide abstract] ABSTRACT: The ultrastructure of spermiogenesis in Wenyonia virilis Woodland, 1923, a caryophyllaeid cestode from the silurid Nile fish Synodontis schall (Bloch et Schneider, 1801), is described by means of transmission electron microscopy (TEM) for the first time. Spermiogenesis
follows the characteristic caryophyllidean type and is initiated by the formation of a differentiation zone. This area, delimited
at its base by a ring of arching membranes and bordered by cortical microtubules, contains two centrioles associated with
typical striated rootlets with a reduced intercentriolar body between them. The apical area of the differentiation zone exhibits
electron-dense material that is present only during the early stages of spermiogenesis. Only one of the centrioles develops
into a free flagellum that grows at an angle of >90° in relation to the cytoplasmic extension. Spermiogenesis is also characterized
by a flagellar rotation and a proximodistal fusion of the flagellum with the cytoplasmic extension. The most interesting features
observed in W virilis are the presence of a reduced, very narrow intercentriolar body and the unique type of flagellar rotation >90°. Results are
compared with those described in two caryophyllideans, Glaridacris catostomi Cooper, 1920 and Khawia armeniaca (Cholodkovski, 1915). Contrary to the original report of Świderski and Mackiewicz (2002), that flagellar rotation has never
been observed in spermiogenesis of G. catostomi, re-assessment of their description and illustrations leads us to conclude that flagellar rotation must logically occur in
that species. The value of various morphological features of sperm in phylogenetic inference is discussed.
No preview · Article · Mar 2008 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: During vitellogenesis in Parachristianella trygonis Trypanorhyncha, Eutetrarhynchidae) we distinguished four stages: (1) gonial or stem cell stage; (2) early differentiation
stage concentrated on protein synthetic activity and shell-globule formation; (3) advanced differentiation stage with main
cell activity concentrated on carbohydrate synthesis (glycogenesis) and massive glycogen storage in the form of α-glycogen
rosettes and β-glycogen particles; and finally (4) mature vitellocyte stage. Early vitellocyte maturation is characterised
by: (1) an increase in cell volume; (2) extensive development of large, parallel cisternae of GER that produce proteinaceous
granules; (3) development of Golgi complexes engaged in packaging this material; (4) continuous enlargement of proteinaceous
granules within vacuoles and their transformation into shell-globule clusters composed of heterogeneous material. Cytochemical
staining with periodic acid-thiosemicarbazide-silver proteinate for polysaccharides indicated a strongly positive reaction
for the presence of α-glycogen rosettes and β-glycogen particles in the advanced stage of vitellocyte maturation. Both protein
synthesis for shell-globule formation and carbohydrate synthesis or glycogenesis, important storage of nutritive reserves
for the developing embryos, observed during cytodifferentiation of P. trygonis vitellocytes overlap in time to some extent. Mature vitelline cells are very rich in three types of cell inclusions accumulated
in large amounts in their cytoplasm: (1) shell-globule clusters, playing an important role in egg-shell formation; (2) numerous
large lipid droplets, as well as a high accumulation of lipid and α-glycogen rosettes and β-glycogen particles that undoubtedly
represent important nutritive reserves for the developing embryos. Despite the fact that the type of vitellogenesis and ultrastructure
of the mature vitellocyte in P. trygonis appears to differ to some extent from those of three other trypanorhynch species, its general pattern and ultrastructure
greatly resembles those observed in other lower cestodes. Factors that may have contributed to the qualitative and quantitative
variation in lipids during vitellogenesis among the four species of Trypanorhyncha, are identified and discussed.
No preview · Article · May 2007 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: The first description of vitellogenesis in the Trypanorhyncha is presented in this paper. Though the type of vitellogenesis
and mature vitellocyte in Dollfusiella spinulifera appear to be unique among the Eucestoda, to some extent they resemble that observed in the lower cestodes, namely the Tetraphyllidea
and Pseudophyllidea. Maturation is characterized by: (1) an increase in cell volume; (2) extensive development of large, parallel,
frequently concentric cisternae of GER that produce proteinaceous granules; (3) development of Golgi complexes engaged in
packaging this material; (4) continuous enlargement of proteinaceous granules within vesicles and their transformation into
shell globule clusters; and (5) progressive fusion of all vesicles, with flocculent material containing the proteinaceous
granules and shell globule clusters, into a single very large vesicle that characterises mature vitellocytes of this tapeworm.
Cell inclusions in and around the large vesicle consist of flocculent material of a very low density, a few shell globule
clusters, moderately dense proteinaceous granules and numerous large droplets of unsaturated lipids. A new previously unreported
mode of transformation of proteinaceous granules into shell globule clusters, that evidently differs from that of pseudophyllideans
and tetraphyllideans, is described. Cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for polysaccharides
indicates a strongly positive reaction for membrane-bound glycoproteins in all membranous structures such as GER, mitochondria,
Golgi complexes, nuclear and cell plasma membranes. Similar staining revealed β-glycogen particles scattered in the cytoplasm
of maturing vitellocytes. Typical cytoplasmic β-glycogen particles appear mainly during early vitellocyte maturation but it
is characteristic for this species that they are only seldom visible in mature cells. Some working hypotheses concerning the
interrelationship between this particular pattern of vitellogensis, possible mode of egg formation in D. spinulifera, its embryonic development and trypanorhynchean life cycle, are drawn and discussed.
Full-text · Article · Aug 2006 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: Development and morphology of the scolex and mode of attachment of Wenyonia virilis Woodland, 1923, a caryophyllaeid cestode from the silurid Nile fish Synodontis schall (Bloch et Schneider, 1801), were studied by means of light and scanning electron microscopy (SEM). Scolex and genital primordia
changes through four stages of juvenile development are described. Longitudinal ridges do not appear on the scolex until the
cestode has well defined genital primordia. This is in stark contrast to other caryophyllidean genera in which the basic morphology
of the adult scolex becomes evident at the procercoid stage in the oligochaete intermediate host. The scolex of the adult
has 13 to 19 prominent longitudinal ridges and deep furrows that come together at the apex to form an apical ring, a protrusible
terminal introvert within the apical ring that forms a deep apical pouch when fully retracted, and a central group of Faserzellen.
The scolex of W. virilis appears similar to the rugomonobothriate scolex of another African caryophyllid, Monobothrioides chalmersius (Woodland, 1924). Comparisons are made with other caryophyllideans having a scolex with a terminal structure: Monobothrium Diesing, 1863, Djombangia Bovien, 1926 and Caryoaustralus Mackiewicz et Blair, 1980. The terminal introvert may be responsible for attachment in early juvenile stages, but may be
supplemented by the longitudinal ridges and furrows later in development. Host tissue appears to be drawn into these furrows
that function as weak organs of attachment. We could not determine how the introvert of adult worms functions in attachment.
At the site of attachment, the mucosa showed necrosis and degeneration and the submucosa exhibited vacuolization and infiltration
with lymphocytes and leucocytes.
Full-text · Article · Mar 2006 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: The present study describes the ultrastructure of mature vitellocytes of the trypanorhynch cestode Progrillotia pastinacae Dollfus, 1946 (Progrillotiidae), a parasite of the common stingray Dasyatis pastinaca (Linnaeus, 1758) (Dasyatidae). The vitelline cells of this species measure about 24 μm in length and about 20 μm in width.
They have small, elongated, slightly lobulated nuclei, about 4–5 μm in length, with large dense elongated nucleoli and numerous
irregularly-shaped dense clumps of heterochromatin. The extensive cytoplasm is rich in numerous cell organelles and cell inclusions.
While the perinuclear cytoplasm contains numerous long parallel cisternae of GER, ribo-and polyribosomes, several Golgi complexes
and mitochondria, the peripheral cytoplasm contains predominantly three types of cell inclusions: a great number of large
lipid droplets, several shell globule clusters, and a very small amount of glycogen-like particles. The most characteristic
features of vitellocytes in P. pastinacae are having almost no traces of glycogen and the great number of large, highly osmiophobic lipid droplets representing saturated
fatty acids. The presence of large amounts of lipids also in two other trypanorhynchs, Grillotia erinaceus (Beneden, 1858) Guiart, 1927 and Dollfusiella spinulifera (Beveridge et Jones, 2000) Beveridge, Neifar et Euzet, 2004, is in strong contrast to the condition in the most evolved cestodes,
Cyclophyllidea, that usually show no trace of lipids.
Full-text · Article · Jan 2006 · Acta Parasitologica
[Show abstract][Hide abstract] ABSTRACT: The fine structure of the ovary, ovicapt, oviduct, fertilisation canal, vitelline ducts, vitelline reservoir, ovovitelline duct, ootype and Mehlis' gland, and proximal, middle and distal parts of the uterus of the spathebothriidean cestode, Cyathocephalus truncatus (Pallas, 1781), from salmoniform fish, has been studied for the first time by transmission electron microscopy (TEM). Emphasis was given to characteristics which might shed light on the unclarified phylogenetic position of spathebothriideans, belonging among the most basal tapeworms (Eucestoda). New for cestodes is the finding of a multinucleate cell that plugs the ovicapt lumen. The morphology of the proximal part of the oviduct resembles that of the pseudophyllidean tapeworm Diphyllobothrium latum. After fertilisation in the fertilisation canal, vitellocytes of C. truncatus become associated with fertilized oocytes in the ovovitelline duct. Only one type of Mehlis' gland secretory cell is present. The eggs with electron-dense eggshells containing large pores first appear in the proximal part of the uterus. The middle portion of the uterus has well-developed uterine glands. The distal portion of the uterus has apical microtriches. Ultrastructural data on the female genital system of C. truncatus are compared and discussed with those for other cestodes. However, on the basis of available ultrastructural data it is not possible to conclude whether the Spathebothriidea are phylogenetically closer to the Caryophyllidea or to the Pseudophyllidea.
Full-text · Article · Dec 2005 · Folia parasitologica