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Ultrastructural studies on the oncospheral envelopes of six species of genus Diorchis [Cyclophyllidea, Hymenolepididae]

100%

Chomicz L.

Acta Parasitologica

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1993

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tom 38

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nr 4

The aim of the present study was to describe ind compare the ultrastructure of oncospheral envelopes in closely related species within the same genus, Diorchis. The envelopes of the following species were examined: Diorchis brevis, D. ovofurcata, D. inflata and D. elisae (filiform, infective eggs), and D. parvogenitalis and D. stefanski (oval shaped eggs). Two categories of oncospheral envelopes are distinguished: the primary cytoplasmic and secondary non-cytoplasmic envelopes. All diorchids examined, in distinction to other hymenolepidids, show at the end of the oncospheral differentiation: (1) a much thicker, clearly striated oncospheral membrane; (2) a three-layered embryophore; (3) the presence of an additional zone of electron-dense aggregates resembling a honeycomb; and (4) an asynchronous differentiation of the derivatives of the inner envelopes. Some ultrastructural differences in oncospheral envelopes of diorchids with oval shaped and filiform oncospheres are described and their significance is discussed.

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

86%

Tkach V., Swiderski Z., Mlocicki D.

Acta Parasitologica

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2013

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tom 58

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nr 3

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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The ultrastructure of the oncospheral envelopes of Fimbriaria czaplinskii Grytner-Ziecina, 1994 [Cestoda, Hymenolepididae]

86%

Chomicz L.

Acta Parasitologica

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1996

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tom 41

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nr 4

The envelopes of oncospheres of a hymenolepidid tapeworm with an aquatic life cycle Fimbriaria czaplinskii, surrounding larvae inside the gravid part of the strobila, were examined under a transmission electron microscope. Details of the ultrastructure of the outer envelope and the inner envelope with its two derivatives: the embryophore and oncospheral membrane are described. The ultrastructural features of F. czaplinskii envelopes are compared and discussed with those described previously in the other hymenolepidids, and particularly with the related species Fimbriaria fasciolaris.

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Ultrastructure of oncospheral envelopes at the final stage of infective - egg formation in some species of Cyclophyllidea

86%

Chomicz L., Walski M.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

5

Electron microscope study on oncospheral envelope morphogenesis in the dilepidid cestode, Dilepis undula [Schrank, 1788]

72%

Swiderski Z., Salamatin R. V., Grytner-Ziecina B., Kornyushin V. V., Conn D. B.

Acta Parasitologica

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2004

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tom 49

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nr 4

The origin, differentiation and ultrastructural characteristics of oncospheral envelopes surrounding invasive oncospheres of the dilepidid cestode Dilepis undula are described. In the early preoncospheral phase three primary embryonic envelopes are formed: (1) the capsule; (2) the outer envelope formed by two macromeres; and (3) the inner envelope originating from fusion of two or three mesomeres. Both the outer and inner envelopes of D. undula are therefore cellular in origin and syncytial in nature. Mature eggs of D. undula are slightly oval, measuring 40-50 x 56 µm in diameter. Within fully formed eggs, the mature, invasive oncospheres, 36-40 µm in diameter, are surrounded by five oncospheral or egg envelopes: (1) outer shell; (2) outer envelope; (3) inner envelope; (4) oncospheral membrane; and (5) hook region membrane covering only one pole of the hexacanth. The ultrastructural characteristics of D. undula oncospheral envelopes are discussed in comparison with those of previously examined dilepidids and other cyclophyllideans.

6

Morphology and fine structure of oncospheral envelopes in gravid proglottids of Diploposthe laevis [Bloch, 1782] Jacobi, 1897 [Cestoda, Hymenolepididae]

72%

Chomicz L., Walski M., Grytner-Ziecina B., Rebandel H.

Acta Parasitologica

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1999

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tom 44

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nr 4

Another hymenolepidid species, Diploposthe laevis (Bloch, 1782) Jacobi, 1897, developing in hosts in an aquatic environment was used to examine oncospheral envelope differentiation and uterus-egg interrelations at the ultrastructural level (SEM and TEM). Inside of the distal proglottids of two D. laevis specimens, the only gravid specimens from among 20 cestodes found, the uterus took the form of wide tubes whose folded walls created chambers in which oncospheres were present within their envelopes. The lumenal surface of the uterus was covered with numerous projections that linked to individual oncospheres forming the uterus-egg interface. Marked differences in the sizes of different oncospheres were visible. Finally, five layers around each Diploposthe laevis oncosphere were revealed: (1) the outer envelope, (2) the distal cytoplasmic portion of the inner envelope, (3) the non-cytoplasmic embryophore, (4) the proximal portion of the inner envelope and (5) the non-cytoplasmic oncospheral membrane. Striking features visible up to the end of the uterine period of formation of D. laevis infective egg were: (1) presence of well-developed outermost envelope, highly folded, rich in cytoplasmic structures, probably complex in origin, and (2) relatively weak development of the embryophore that was one-layered, moderate electrondense, with the granular material never forming a very compact envelope.

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Fine structure of the infective eggs of the dilepidid cestode Hepatocestus hepaticus [Baer, 1932], a parasite of shrews

72%

Swiderski Z., Tkach V. V., Vaucher C.

Acta Parasitologica

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2000

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tom 45

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nr 2

Ultrastructural characteristics of the eggs of the dilepidid cestode, Hepatocestus hepaticus, is described. The mature oncosphere is surrounded by three envelopes: (1) an outer envelope; (2) an inner envelope consisting of three layers - an extraembryophoral cytoplasmic layer, a thick, fibrillar, low electron-dense embryophore, and intraembryophoral cytoplasmic layer, (3) a thin oncospheral membrane, surrounding the oncosphere. The whole surface of the oncosphere is covered by the cytoplasmic oncospheral tegument with numerous short microvilli and a layer of subtegumental somatic muscles. The following cell types were distinguished in the mature oncospheres: the U-shaped penetration gland a containing a large amount of tightly packed secretory granules; bi-nucleate perikaryon of the oncospheral tegument; somatic cells (= myocytons of somatic and hook muscles); and the germinative cells. The hook-muscle system consists of three pairs of embryonic hooks and a complex system of specialised muscle fibers responsible for the coordinated hook movements. The ultrastructural characteristics of H. hepaticus oncosphere are discussed in comparison with those of previously studied dilepidids and other cyclophyllideans.

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Functional ultrastructure of the oncospheral envelopes of twelve hymenolepidid species with aquatic life cycle s

72%

Chomicz L., Swiderski Z.

Acta Parasitologica

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2004

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tom 49

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nr 3

Most of the previous studies on the functional ultrastructure of oncospheral envelopes in cestodes are restricted to hymenolepidids with terrestrial life cycles, mainly parasites of mammals. The purpose of the present study is to describe and compare origin, differentiation and functional ultrastructure of oncospheral envelopes of 12 cestode species with aquatic life cycles examined by means of transmission (TEM) and scanning electron microscopy (SEM) techniques. Results of our comparative electron microscopical studies revealed that despite the general similarities in the ultrastructure of the primary envelopes surrounding developing embryos, there exist important differences both in the type of morphogenesis and in the final form and arrangement of the secondary envelopes between the 12 examined hymenolepidids. In all examined species, the embryophore develops within the syncytial layer of the primary inner envelope and is transformed into a heterogeneous structure in the final phase of infective egg formation. Some ultrastructural features of oncospheral envelopes are very characteristic for the cestode species examined, and may indeed represent a new useful criterion for differential diagnosis. Our data on ultramorphology of the envelopes and their connections with the uterine wall may also be useful for better understanding of the developmental physiology and biology of the oncospheral stage of hymenolepidids with aquatic life cycles. The comparative analysis allows determination of some ultrastructural features that adapt oncospheres to the behavior and habitat of their intermediate hosts. Interrelations among the ultrastructure of the oncospheral envelopes, habitat of crustacean intermediate hosts, and cestode life cycles are drawn and discussed.

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Differentiation and ultrastructure of the oncospheral envelopes of the cestode Joyeuxiella echinorhyncoides [Sonsino, 1889] [Cyclophyllidea, Dipylidiidae]

72%

Swiderski Z., Miquel J., Agostini S., Conn D. B., Chomicz L., Grytner-Ziecina B.

Acta Parasitologica

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2004

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tom 49

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nr 3

In the preoncospheral stage of development of Joyeuxiella echinorhyncoides three primary embryonic envelopes are formed: (1) the capsule; (2) the outer envelope formed by two macromeres, and (3) the inner envelope originating from fusion of three mesomeres. Both the outer and inner envelopes of J. echinorhyncoides are therefore cellular in origin and syncytial in nature. Mature eggs of J. echinorhyncoides are spherical, measuring 47-60 x 38-48 µm in diameter. Each uterine capsule contains one egg. Within fully formed eggs, the mature oncospheres, 25-27 µm in diameter, are surrounded by five oncospheral or egg envelopes: (1) the outer shell, which originates from the initially delicate membranous capsule that becomes encrusted by the uterine-derived shell material that is deposited on it; (2) the outer envelope, still containing two large macromere nuclei; (3) the inner envelope, with three characteristic nuclei of mesomeres, and which secretes the electron-dense protective embryophore layer at its outer surface; (4) a unique type of “oncospheral membrane” that never becomes delaminated or detached from the rest of the inner envelope as a separate layer; and (5) a surface filament layer, composed of numerous elongated processes separated by cisternae containing material of very high electron density. The so-called “hook region membrane” covers only one pole of the mature oncosphere and is directly attached to the oncosphere surface. The ultrastructure of the oncospheral envelopes in J. echinorhyncoides shows some similarity to that described in the only other species of dipylidiid cestode examined to date, the cosmopolitan type-species, Dipylidium caninum. Differences between these two species include the absence of “hook region membrane”, as well as bilayered and striated embryophore unique to D. caninum, and the undetached “oncospheral membrane” and unique “surface filament layer” and “interdigitating cisternae”, characteristic of J. echinorhyncoides eggs.

10

Ultrastructure of the oncospheral envelopes in the pseudophyllidean cestode Eubothrium salvelini [Schrank, 1790]

58%

Swiderski Z., Brunanska M., Mlocicki D., Conn D. B.

Acta Parasitologica

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2005

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tom 50

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nr 4

The aim of this study is to describe the ultrastructure of oncospheral envelopes in the pseudophyllidean cestode Eubothrium salvelini, a parasite of salmonid fishes. Our results indicate that the eggs of E. salvelini differ in their ultrastructure from those of the majority of the Pseudophyllidea. The entire embryonic development, including differentiation of the mature, infective oncosphere of E. salvelini takes place in the uterus and not in the aquatic environment, as is common for other pseudophyllideans. Egg maturation is not simultaneous; together with mature eggs containing fully differentiated oncospheres, can be found numerous small immature, nonfertilized and nonviable abortive eggs. The normally developing eggs of E. salvelini are large, oval and nonoperculated. Three envelopes surround the infective hexacanths: (1) the eggshell; (2) the outer envelope originating from macromere fusion; (3) the inner envelope formed by numerous mesomeres which usually persist in the mature eggs. Our observations confirm that both the outer and the inner envelopes of E. salvelini eggs are cellular in origin and syncytial in nature. The typical oncospheral membrane was not observed in this species. New data on the origin and ultrastructure of oncospheral envelopes may present useful criteria for phylogenetic analysis of lower cestodes. Ontogenetic characters, such as ultrastructural aspect of morphogenesis of infective larval stages, are proposed as phylogenetic indicators in studies of cestode evolution.

11

Ultrastructural studies on the oncospheral envelopes of hymenolepidid cestode, Wardium aequabile [Rudolphi, 1810] Spassky et Spasskaya, 1954, in the final stage on infective egg formation

58%

Chomicz L., Cielecka D., Walski M., Czubaj A.

Acta Parasitologica

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1997

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tom 42

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nr 1

The oncospheral envelope morphology, representing an useful criterion in the taxonomy of cestodes, were examined, at the ultrastructural level, in hymenolepidid Wardium aequabile, developing in hosts connected with an aquatic environment. Adult specimens of the cestode from swan, processed for ТЕМ, were analysed. Inside the uterus, around each oncosphere the following envelopes were observed: the outer and the inner envelopes, the embryophore and the oncospheral membrane. The lumenal side of the uterus forms compact layer, rich in cytoplasmic components and intruding between individual eggs. There were certain features characteristic for W. aequabile: (1) details of ultrastructure of the outer envelope and uterine wall; (2) the embryophore with thick electron-dense core layer; (3) the long hooked appendage at each pole of the egg, inside the inner envelope, with the embryophore penetrating into the appendages. Significance of ultrastructural features of W. aequabile in relation to life cycle of the cestode is discussed and, differences and similarity with other hymenolepidids developing in hosts in aquatic environment are presented.

12

Differentiation and ultrastructure of the oncospheral envelopes in the hymenolepidid cestode Staphylocystoides stefanskii [Zarnowski, 1954]

58%

Tkach V. V., Swiderski Z.

Acta Parasitologica

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1998

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tom 43

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nr 4

Ultrastructure of the oncospheral envelopes in developing and fully formed eggs of the hymenolepidid cestode, Staphylocystoides stefanskii (Zarnowski, 1954), is described. The uterus in this species is saccular, with deep infoldings of the uterine wall which form pocket-like structures. The uterine wall is composed by a flat syncytial uterine epithelium containing elongated nuclei with prominent nucleoli. The differentiating and mature oncospheres are surrounded by three envelopes: (1) an outer envelope; (2) an inner envelope consisting of three layers - an extraembryophoral cytoplasmic layer, a dense and relatively thick embryophore, and an intraembryophoral cytoplasmic layer; (3) a thin oncospheral membrane, surrounding the oncosphere. The outer envelope usually contains 2 nuclei in the preoncospheral stage, however, no nuclei were observed in this layer in the fully formed eggs. The inner envelope shows in sectioned material 1-2 nuclei in its intraembryophoral layer. The extraembryophoral layer of the inner envelope increases in thickness during the egg maturation. The embryophore was initially discontinuous, formed by the blocks of the electron-dense substance, and situated directly under the outer limiting membrane of the inner envelope. Later the neighbouring blocks fuse together and finally produce a continuous dense layer of embryophore. The embryophore remains slightly vacuolised for some time and finally forms a thick homogeneously electron-dense layer. The oncospheral membrane appears striated on the high-power micrographs. The ultrastructure of oncospheral envelopes in S. stefanskii is compared with those in other mammalian hymenolepidids.

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Verification of features of the genus Fimbriaria [Froelich, 1802] and a key to the identification of species

51%

Grytner-Ziecina B., Cielecka D., Chomicz L., Ziecina R.

Acta Parasitologica

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1998

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tom 43

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nr 3

Knowledge to date on the morphology of Fimbriaria tapeworms is summarised, with features of the genus being verified and augmented by some not previously taken account of, like the ultrastructure of the tegument. The most important features in accurate identification to the level of the species are the structure of the oncospheral envelope and the manner in which eggs are released from the uterus. Other features of diagnostic importance are the number of primordia of reproductive organs, the number of hooks at the cirrus base and the dimensions of the cirrus and cirrus pouches. A key to the identification of species is provided.

14

Electron microscopical studies on the cellular organisation of the oncospheres of the hymenolepidid cestode, Staphylocystoides stefanskii [Zarnowski, 1954]

51%

Swiderski Z., Tkach V. V.

Acta Parasitologica

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1999

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tom 44

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nr 1

The cellular organisation of the oncospheres of S. stefanskii has been examined by means of light and transmission electron microscopy. The reconstruction of hexacanth larvae was based on serial semithin sections and its results have been correlated with partial reconstruction from ultrathin sections. The surface of the oncospheres was covered by a thin layer of oncospheral tegument. Five major cell types have been distinguished in mature oncospheres of S. stefanskii: (1) about 10 germinative cells, situated in the posterior pole of the oncosphere; (2) about 36 somatic cells (= myocytons of somatic and hook muscles); (3) a bi-nucleate medullary centre representing a perikaryon of oncospheral tegument; (4) a bi-nucleate, U-shaped penetration gland and (5) two nerve cells containing characteristic dense-core vesicles. The total number of cells in mature oncospheres was thus about 50, while the number of nuclei was about 52. The hook-muscle system of oncospheres, composed of peripheral and hook muscles, is similar to that described in other cyclophyllideans. The oncospheral hooks were formed in specialised hook-forming cells or oncoblasts. The oncoblasts are retained in mature oncospheres only as a thin layer of anucleated cytoplasm around the hook handle region, which seems to be a common feature for the mammalian hymenolepidids. The data on the oncospheral cell types and their number are in agreement with formerly proposed hypothesis (Swiderski 1972, 1983), assuming that the progressive reduction in number of oncospheral cells is one of the characteristic features in cestode evolution.

15

Ultrastructural studies on the cellular organisation of the oncospheres of the nematotaeniid cestode, Nematotaenia dispar [Goeze, 1782]

51%

Swiderski Z., Tkach V. V.

Acta Parasitologica

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1997

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tom 42

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nr 3

A complete reconstruction of the constituents of the mature egg of N. dispar has been attempted at the light microscope level based on serial semithin sections, and results have been correlated with partial reconstruction from ultrathin sections. The outer coat of the oncosphere consists of an anucleate cytoplasmic layer of tegument, a basal lamina, and two layers of peripheral, somatic musculature. The oncospheral hooks and their associated muscle system, situated in the anterior pole of the larvae, together with penetration gland secretion appear to play an important role in host tissue penetration. The bases of each lateral hook pair are joined by a common zone of “connective” material whereas the medial hook bases are embedded in individual cups of this material. Five major types of oncospheral cells have been distinguished. These consisted of: (1) a bi-nucleate medullary centre (= subtegumental cell); (2) a bi-nucleate, U-shaped penetration gland; (3) two nerve cells of neurosecretory type; (4) about 34 somatic cells (= cell bodies of somatic and hook muscles); and (5) about 12 germinative cells, arranged in two groups of six cells, situated in the posterior pole of the hexacanth. The position of oncospheral structures remains fixed in relation to one another but at the same time is somewhat arbitrary due to the high plasticity of the hexacanth during movements.

Ograniczanie wyników

Ultrastructural studies on the oncospheral envelopes of six species of genus Diorchis [Cyclophyllidea, Hymenolepididae]

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

The ultrastructure of the oncospheral envelopes of Fimbriaria czaplinskii Grytner-Ziecina, 1994 [Cestoda, Hymenolepididae]

Ultrastructure of oncospheral envelopes at the final stage of infective - egg formation in some species of Cyclophyllidea

Electron microscope study on oncospheral envelope morphogenesis in the dilepidid cestode, Dilepis undula [Schrank, 1788]

Morphology and fine structure of oncospheral envelopes in gravid proglottids of Diploposthe laevis [Bloch, 1782] Jacobi, 1897 [Cestoda, Hymenolepididae]

Fine structure of the infective eggs of the dilepidid cestode Hepatocestus hepaticus [Baer, 1932], a parasite of shrews

Functional ultrastructure of the oncospheral envelopes of twelve hymenolepidid species with aquatic life cycle s

Differentiation and ultrastructure of the oncospheral envelopes of the cestode Joyeuxiella echinorhyncoides [Sonsino, 1889] [Cyclophyllidea, Dipylidiidae]

Ultrastructure of the oncospheral envelopes in the pseudophyllidean cestode Eubothrium salvelini [Schrank, 1790]

Ultrastructural studies on the oncospheral envelopes of hymenolepidid cestode, Wardium aequabile [Rudolphi, 1810] Spassky et Spasskaya, 1954, in the final stage on infective egg formation

Differentiation and ultrastructure of the oncospheral envelopes in the hymenolepidid cestode Staphylocystoides stefanskii [Zarnowski, 1954]

Verification of features of the genus Fimbriaria [Froelich, 1802] and a key to the identification of species

Electron microscopical studies on the cellular organisation of the oncospheres of the hymenolepidid cestode, Staphylocystoides stefanskii [Zarnowski, 1954]

Ultrastructural studies on the cellular organisation of the oncospheres of the nematotaeniid cestode, Nematotaenia dispar [Goeze, 1782]