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Origin of the accessory sac in hymenolepidid cestodes

100%

Czaplinski B., Czaplinska U., Cielecka D.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

2

Morphological studies on envelopes of oncospheres of the hymenolepidid cestode, Fimbriaria fasciolaris [Pallas, 1781]

100%

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

Acta Parasitologica

|

1995

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tom 40

|

nr 1

The envelopes of oncospheres of Fimbriaria fasciolaris, found in the distal part of the strobila or free, were the subject of scanning electron microscope (SEM) and light microscope (LM) studies. The oncospheres inside the strobila were in close apposition to the uterine wall and showed morphological ties suggesting metabolic interactions. SEM studies allowed us to discern 3 stages of uterine development: early - with a continuous, tubular, and branched uterus; intermediate - with bulging parts of the uterus forming uterine capsules packed with oncospheres; late - with the uterus discontinuous, breaking down into uterine capsules, either individual or connected into chains of different lengths, containing 1 to 12 oncospheres. The uterine epithelium within uterine capsules was structurally heterogeneous, closely connected with the oncospheres, constituting a common uterine envelope. Infective eggs outside the strobila were deprived of the uterine envelope, and were joined together by separate external envelopes, easily visible in the LM. Live oncospheres observed over a 24 h period after liberation from the strobila exhibited alterations in taxonomically important features, such as dimensions and shape of the external envelope. The possible roles of different envelopes are discussed.

3

Ultrastructure of oncospheral envelopes and their differentiation in the cestode, Dicranotaenia coronula [Dujardin, 1845] [Cyclophyllidea, Hymenolepididae]

67%

Chomicz L., Swiderski Z., Grytner-Ziecina B.

Acta Parasitologica

|

1995

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tom 40

|

nr 1

Studies of the ultrastructure of oncospheral envelopes and their differentiation in the hymenolepidid cestode Dicranotaenia coronula in utero revealed four main envelopes: (1) capsule, (2) outer envelope, (3) inner envelope with a thin, electron-dense embryophore, and (4) oncospheral membrane. An additional hemispherical calotte, the hook region membrane covers one pole of the oncosphere and is attached to its surface. Both the outer and inner envelope represent syncytial layers which contain large, flattened nuclei of blastomeres which participated in their formation: nuclei of macromeres in the outer, and nuclei of mesomeres in the inner envelope. The granular cytoplasm of the both envelopes contains a large amount of free ribosomes, numerous mitochondria and several lipid droplets. The primary inner envelope of the early embryo forms in the later stage of embryogenesis its two derivatives: the embryophore and the oncospheral membrane. The hook region membrane oryginates from a syncytial binucleate complex by delamination of its cytoplasmic plate. Both the ultrastructural features of oncospheral envelopes and mode of their differentiation are compared with those described previously in the other hymenolepidids with aquatic and terrestrial life cycles. The ultrastructure of the oncospheral envelopes in D. coronula is discussed in relation to its life cycle and to environmental conditions in which the infective eggs remain for a certain period of time, until eaten by benthal ostracods, the intermediate hosts of D. coronula.

4

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

67%

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.

5

Ultrastructure of the infective eggs of the hymenolepidid cestode, Ditestolepis tripartita [Zarnowski, 1955], a parasite of shrews

67%

Swiderski Z., Tkach V.

Acta Parasitologica

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1997

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tom 42

|

nr 1

The ultrastructure of infective eggs of the hymenolepidid cestode, Ditestolepis tripartita, a parasite of shrews, was examined with emphasis on cellular organisation of mature oncospheres. Each hexacanth larva is surrounded by three main egg envelopes: thin layer of amorphous outer envelope, relatively thick layer of inner envelope with an embryophore and a delicate oncospheral membrane. The outer and inner envelopes of infective eggs of D. tripartita are usually amorphous; the embryophore is relatively thin and moderately electron-dense. Five major types of oncospheral cells have been distinguished. These consist of: (1) about ten germinative cells; (2) about 30 somatic cells (= myocytons of somatic and hook muscles); (3) a bi-nucleate medullary centre (= tegumental perikaryon); (4) a bi-nucleate, U-shaped penetration gland and (5) two cells of neurosecretory type with characteristic dense-cored vesicles. The hook-muscle system with complex interconnections between different muscle fibers provides a structural basis for coordinated hook action.

6

Cestodes of shrews [Insectivora, Soricidae] from the Magadan region, North-East Siberia

67%

Novikov M. V.

Acta Parasitologica

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1995

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tom 40

|

nr 1

Five species of Sorex shrews (S. caecutiens, S. isodon, S. daphaenodon, S. gracillimus and S. minutissimus) were studied for helminths in North-East Asia. 11 cestode species were described. For 5 of them S. isodon and S. gracillimus were recorded as new hosts. Geographical distribution and community structure of found cestodes are briefly analyzed. A role of different shrew species in the helminth circulation is also discussed.

7

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

67%

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.

8

Late stages of egg maturation in the cestode Pseudhymenolepis redonica Joyeux et Baer, 1935 [Cyclophyllidea, Hymenolepididae], a parasite of shrews

59%

Tkach V. V., Swiderski Z.

Acta Parasitologica

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1997

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tom 42

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nr 2

Ultrastructural characteristics of developing eggs in the late preoncospheral and oncospheral stage and that of the uterine capsules in the hymenolepidid cestode, Pseudhymenolepis redonica Joyeux et Baer, 1935, are described. The uterus in this species breaks down very early into uniovular capsules. The uterine wall consisted of a syncytial flat uterine epithelium separated from the medullary parenchyma by a thin extracellular basal matrix. The uterine epithelium contained elongated nuclei with prominent nucleoli in the juxtalumenal cytoplasm. Its apical plasma membrane was folded into long microlamellae. The differentiating and mature oncosphere were surrounded by three envelopes: (1) an outer envelope, still containing the nuclei in the preoncospheral stage; (2) an inner envelope consisting of three layers - an extraembryophoral cytoplasmic layer, a thin and discontinuous embryophore, and intraembryophoral cytoplasmic layer; (3) a thin oncospheral membrane, closely surrounding the oncosphere. The relative thickness of the extraembryophoral and intraembryophoral layers of the inner envelope was changing during egg maturation. The numerous small mitochondria which were initially present only in the intraembryophoral layer, were concentrated later in the extraembryophoral layer and in many cases were observed in the embryophoral pores. The above data may suggest that these cytoplasmic organelles are pushed through the embryophoral pores as a result of the pressure of the developing oncosphere. The oncosphere surface was covered by the cytoplasmic oncospheral tegument, basal lamina and a layer of subtegumental somatic muscles. Several cell types were distinguished in the differentiating and mature oncospheres, namely: the germinative cells; somatic cells (= myocytons of somatic and hook muscles); the bi-lobed penetration gland with its secretory granules; the “neurosecretory” cells with their characteristic dense-cored membrane-bound vesicles. Each oncosphere had three pairs of embryonic hooks: one median, one dorso-lateral and one ventro-lateral pair. The degenerating hook-forming cells or oncoblasts remained visible around the hook handles. The details of the ultrastructure of the uterine capsules, oncospheral envelopes and different cell types of differentiating and mature oncospheres of P. redonica are discussed in comparison with literature data on other hymenolepidids, parasites of mammals and birds.

9

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

59%

Swiderski Z., Tkach V. V.

Acta Parasitologica

|

1999

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tom 44

|

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.

Ograniczanie wyników

8 Acta Parasitologica

1 Wiadomości Parazytologiczne

5 Swiderski Z.

3 Chomicz L.

3 Tkach V. V.

2 Cielecka D.

2 Grytner-Ziecina B.

2 Walski M.

1 Czaplinska U.

1 Czaplinski B.

1 Czubaj A.

1 Novikov M. V.

1 Tkach V.

1 1999

2 1998

3 1997

3 1995

Origin of the accessory sac in hymenolepidid cestodes

Morphological studies on envelopes of oncospheres of the hymenolepidid cestode, Fimbriaria fasciolaris [Pallas, 1781]

Ultrastructure of oncospheral envelopes and their differentiation in the cestode, Dicranotaenia coronula [Dujardin, 1845] [Cyclophyllidea, Hymenolepididae]

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

Ultrastructure of the infective eggs of the hymenolepidid cestode, Ditestolepis tripartita [Zarnowski, 1955], a parasite of shrews

Cestodes of shrews [Insectivora, Soricidae] from the Magadan region, North-East Siberia

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

Late stages of egg maturation in the cestode Pseudhymenolepis redonica Joyeux et Baer, 1935 [Cyclophyllidea, Hymenolepididae], a parasite of shrews

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