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Scolex development, morphology and mode of attachment of Wenyonia virilis Woodland, 1923 [Cestoidea, Caryophyllidea]

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Ibraheem M. H. , Mackiewicz J. S.

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nr 1

EN

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.

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Ultrastructural and cytochemical studies on vitellogenesis in the trypanorhynch cestode Parachristianella trygonis Dollfus, 1946 [Eutetrarhynchidae]

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Swiderski Z. , Miquel J. , Neifar L. , Mackiewicz J. S.

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nr 2

EN

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.

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Ultrastructure and cytochemistry of vitellogenesis in Wenyonia virilis Woodland, 1923 [Cestoda, Caryophyllidea]

61%

Swiderski Z. , Mlocicki D. , Mackiewicz J. S. , Miquel J. , Ibraheem M. H. , Brunanska M.

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nr 2

131-142

EN

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 and discussed.

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Ultrastructural and cytochemical studies on vitellogenesis in trypanorhynch cestode Dollfusiella spinulifera Beveridge, Neifar et Euzet, 2004 [Eutetrarhynchidae]

61%

Swiderski Z. , Miquel J. , Mlocicki D. , Neifar L. , Grytner-Ziecina B. , Mackiewicz J. S.

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nr 3

EN

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.