Ultrastructural study of the oncospheral envelope differentiation in the hymenolepidid cestode Staphylocystoides stefanskii (Zarnowski, 1954)

Tkach, Vasyl V.; Z, Swiderski

doi:10.1016/s1383-5769(98)80351-6

Cited by 5 publications

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“…24 General topography of the infective oncosphere surrounded by the egg envelopes. Note: (1) a rigid, electron dense capsule/outer shell (OS); (2) a thick, cytoplasmic, extraembryophoral layer of the inner envelope (IE1); (3) an electron-dense embryophore (Em) (pyriform apparatus); (4) the mesomere nuclei (MeN), which remain inside the granular intraembryophoral layer of the inner envelope (IE2); and (5) The present TEM study indicates that the formation of the outer envelope is unique in comparison with other cyclophyllideans (Swiderski 1968;Rybicka 1972;Coil 1979;Conn 1985aConn , 1985bTkach and Swiderski 1998;Swiderski et al 2001). According to our knowledge, displacement or ''migration'' of the macromere nuclei in the syncytial cytoplasm of the outer envelope into one of its poles has never been described previously in other species.…”

Section: Discussionmentioning

confidence: 93%

An ultrastructural study of embryonic envelope formation in the anoplocephalid cestode Mosgovoyia ctenoides (Railliet, 1890) Beveridge, 1978

et al. 2005

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In this study the ultrastructural aspects of egg envelope formation in the anoplocephalid cestode Mosgovoyia ctenoides are described. In the early stage of oncospheral morphogenesis, formation of three following primary embryonic envelopes takes place: (1) the capsule, (2) the outer envelope, and (3) the inner envelope. The capsule is formed from the vitellocyte material. Two macromeres contribute to the formation of the outer envelope and three mesomeres take part in the formation of the inner envelope. The three primary envelopes undergo further differentiation and transformation into the secondary envelopes, the so-called oncospheral or egg envelopes. In the advanced preoncospheral phase, the inner envelope undergoes differentiation into three sublayers: (1) a thick extra-embryophoral cytoplasmic layer; (2) an electron-dense embryophore, as a stiff pyriform apparatus; and (3) a thin intra-embryophoral cytoplasmic layer containing mesomere nuclei. The oncosphere is located in the extended cupule-like part of the pyriform apparatus. The two embryophoral horns elongate and fuse, thus forming a rigid cone. Four egg envelopes surround the mature infective oncosphere of M. ctenoides: (1) a thick capsule; (2) the outer envelope; (3) the inner envelope with a characteristic embryophore, in the form of the pyriform apparatus; and (4) the oncospheral membrane. The differentiation and ultrastructure of the egg envelopes of M. ctenoides are compared, in particular to those described in other anoplocephalids, and in general to the oncospheres of other cestode species.

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Section: Discussionmentioning

confidence: 93%

An ultrastructural study of embryonic envelope formation in the anoplocephalid cestode Mosgovoyia ctenoides (Railliet, 1890) Beveridge, 1978

et al. 2005

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“…However, its origin and stage of formation is completely different. A typical oncospheral membrane is an anucleated structure and appears at the final stage of embryonic development and originates from delamination of the innermost layer of the inner envelope (Tkach and Świderski 1998;Świderski et al 2001;Młocicki et al 2005). Embryonic envelopes were not detected neither during the early development of the caryophyllidean Archigetes appendiculatus by Motomura (1929) and in two species of Khawia by Scholz (1991Scholz ( , 1993; however, these observations were at the light microscope level.…”

Section: Discussionmentioning

confidence: 98%

Early intrauterine embryonic development in Khawia sinensis Hsü, 1935 (Cestoda, Caryophyllidea, Lytocestidae), an invasive tapeworm of carp (Cyprinus carpio): an ultrastructural study

et al. 2011

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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.

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“…Note the difference and thickness of corresponding layers of different species, unusual position of the embryophore in R. nana and presence of thick egg outer coat in species from rodents (upper row) and its absence in hymenolepidids of soricomorphs (lower row) and T. biremis. Modified after Tkach and Świderski (1998) that are frequently characteristic for each family. For example, the ultrastructure of anoplocephalid eggs with very robust and thick protective envelopes as described in Anoplocephaloides dentata by Świderski et al (2001) and in Mosgovoyia ctenoides by Młocicki et al (2005), shows differentiation of a characteristic embryophore in the form of the pyriform apparatus.…”

Section: Discussionmentioning

confidence: 99%

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

Tkach

Świderski

Młocicki

2013

Acta Parasitologica

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This is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

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Ultrastructural study of the oncospheral envelope differentiation in the hymenolepidid cestode Staphylocystoides stefanskii (Zarnowski, 1954)

Cited by 5 publications

References 0 publications

An ultrastructural study of embryonic envelope formation in the anoplocephalid cestode Mosgovoyia ctenoides (Railliet, 1890) Beveridge, 1978

An ultrastructural study of embryonic envelope formation in the anoplocephalid cestode Mosgovoyia ctenoides (Railliet, 1890) Beveridge, 1978

Early intrauterine embryonic development in Khawia sinensis Hsü, 1935 (Cestoda, Caryophyllidea, Lytocestidae), an invasive tapeworm of carp (Cyprinus carpio): an ultrastructural study

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

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