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Z Swiderski

Publications and source records attributed to Z Swiderski.

36 records · Page 2Linked to original sources
PubMed1981

[Comparative fine structure of the cestode spermatozoon. Relationship to phylogenesis].

The comparison of the ultrastructure of spermatozoa in Cestodes from seven different orders shows that they have the same general pattern of organization. The main common features are following: (a) a long thread-like body; (b) an elongated nucleus; (c) cortical microtubules underlying plasma membrane; (d) the absence of mitochondria and of a typical acrosome. The mode of spermatozoon differentiation indicates an inversion of the polarity. The number of axonemes of the 9 + "1" pattern, characteristic of the platyhelminthes, allow us to distinguish two types of spermatozoa among cestodes: --The "two-axonemes"-type is considered as primitive as it has also been found in the free-living platyhelminths. This type has been observed in the Pseudophyllidea, Proteocephalidea, Tetrarhynchidea and Tetraphyllidea (Onchobothriidae). --The "one-axoneme"-type has been found in the Cyclophyllidea, Caryophyllaeidea, Diphyllidea and Tetraphyllidea (Phyllobothriidae). It has been proved that the one axoneme type of the spermatozoon, observed in Tetraphyllidea, Phyllobothriidae arises from the two axoneme type by early abortion of the second axoneme. In all the tetraphyllidean species studied so far, we found an helicoidal body forming so-called "crested body" or "spiral crest" at the proximal end of the spermatozoon, which is opposite to the nuclear part. This division of the cestodes into two groups, according to the number of axonemes in the spermatozoon is compared with the phylogenetic diagrammes of Cestoda proposed by Freeman (1973) and Euzet (1974). As result, two hypothesis can be forwarded to explain the relationships between the Tetraphyllidea, Proteocephalidea and Cyclophyllidea. The importance of data on the cestode spermatozoa as a criterion in analysis of cestode phylogenesis is drawn and discussed.

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PubMed1980

Regional specialization of the sperm membrane in the tick Amblyomma hebraeum koch (Acari: Ixodidae).

The spermatozoon of Amblyomma hebraeum is about 200 micrometers long and comprises: (l)a thick, club-shaped anterior part, about 20 micrometers long bearing at its apex a "tactile" hemisphere, and (2) an elongated tail-like part, about 180 micrometers long. The surface of the "tactile" hemisphere is covered by numerous bulbous expansions, attached to it by short stalks. The base of the hemisphere is surrounded by a fringe of thin motile processes; the remaining surface of the spermatozoon is covered with long cellular processes which run more or less parallel to one another. The membrane-associated particles found on the membrane beneath the cellular processes are regularly arranged as groups of parallel strands. The external surface of the so-called "peripheral granules", as revealed by freeze-etching, is smooth with a very small number of particles. Internally the particles exhibit a regular hexagonal pattern which has not been observed, so far, on any other membrane of these sperm cells. The regional specialization of the spermatozoon surface membrane in relation to sperm motility is discussed. The results obtained indicate that processes of three types: (1) bulbous expansions, (2) motile processes, and (3) cellular processes are regional specializations, all engaged in aspects of sperm motility.

Acrosome↗
PubMed1980

[Spermatogenesis of Bothriocephalus clavibothrium Ariola, 1899 (Cestoda: Pseudophyllidea)].

The processes of spermatogenesis and spermiogenesis in the Pseudophyllidea Cestode Bothriocephalus clavibothrium were studied by light and electron microscopy. Spermatogenesis is for rosette type. The rosettes of secondary, tertiary and quaternary spermatogonia, primary and secondary spermatocytes and spermatid clusters are all resulting of a series of six incomplete, synchronous divisions (4 mitosis and 2 meiotic kinesis). The 64 nuclear syncytium of spermatids, during spermiogenesis process gives 64 mature spermatozoa, all originating from a single primary spermatogonium. The sperm differentiation is characterized by: 1. -- Formation of the differentiation zone containing an intercentriolar body and two basal bodies of the future axonemes; 2. -- Formation of a cytoplasmic expansion and induction of two flagella; 3. -- Migration of nucleus into medial cytoplasmic expansion inducing progressive longitudinal fusion of the later with two adjacent flagella into a single spermatozoon body. The filiforme spermatozoa of B. clavibothrium are about 300 micrometer long and their main components are . the nucleus, two axonemes, cortical microtubules and cytoplasm rich in beta-glycogen particles.

Animals↗
PubMed1978

Morphology of the spermatid and spermatozoon of Amblyomma hebraeum Koch (Acarina; Ixodidae).

Spermatids and spermatozoa of Amblyomma hebraeum were examined by scanning and transmission electron microscopy as well as by freeze-etch and freeze-fracture techniques. The external surface of the spermatid is smooth except for a rim of two parallel grooves near the anterior apex. This rim probably marks the level at which a cap detaches, permitting extrusion of the inner cord during spermatozoon maturation. Both ends of the spermatid are closed, the anterior part being slightly thicker than the posterior. The spermatozoon is clavate anteriorly and tail-like posteriorly. The tip of the anterior part is a hemispherical structures carrying numerous bulbous expansions. Apart from the hemispherical structure, the entire spermatozoon surface is covered with parallel longitudinal cellular processes. Waves of constrictions on the tail-like part of the spermatozoon and undulations of the cellular processes are considered to be involved in sperm motility.

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PubMed1976

[Vitellogenesis in Echeneibothrium beauchampi Euzet, 1959 (Cestoda: Tetraphyllidea, Phyllobothriidae) (author's transl)].

The vitellogenesis in Echeneibothrium beauchampi is studied by means of electron microscopy. In the follicles, the vitelline cells undergo three progressive changes characterized by cellular size, membrane system development and nature of stored inclusions. 1. Immature cells have a gonial morphology. 2. Maturing cells display a very well developed membrane system. Their cytoplasm is gradually filled with abundant lipid droplets. At the same time, a small number of homogeneous vesicles occur which contain protein material moderately electron dense. Glycogen (alpha and beta) appears at the end of the vitellogenesis. 3. Mature cells show a conspicuous regression of the membrane system. Cellular organelles, nucleus and protein vesicles are found in the peripheral cytoplasmic layer which still contains numerous free ribosomes. The amorphous remaining cytoplasm is filled with large amounts of aggregated lipid droplets which often surround glycogen areas. 4. The presence of numerous lipid droplets and glycogen in the vitelline cells of E. beauchampi shows evidence that this Tetraphyllidea is close to Pseudophyllidea, but the aspect of protein vesicles (shell-protein material) brings it near the Cyclophyllidea.

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PubMed1975

[Electron microscope study of spermatogenesis in two cestodes acanthobothrium filicolle benedenii Loennberg, 1889 and Onchobothrium uncinatum (Rud., 1819) (Tetraphyllidea, Onchobothriidae) (author's transl)].

The spermatogenesis, spermatozoon differentiation and fine structure of Acanthobothrium filicolle benedenii Loennberg, 1889 and Onchobothrium uncinatum (Rud., 1819) were studied by means of light and electron microscopy. Spermatogenesis in both species is of the rosette type. During sperm differentiation, the five following stages have been distinguished: (1) formation of arching membranes and differentiation zone; (2) nuclear elongation; (3) formation of two flagella with a median cytoplasmic process; (4) flagellar rotation; (5) fusion of two flagella with the median cytoplasmic process induced by the migration of nucleus into the latter. The mature spermatozoa of both species are threadlike structures about 250 mum long. They consist of two axonemes of the platyhelminth type (9+1 pattern), elongated nucleus and cortical microtubules embedded in a cytoplasmic matrix containing numerus beta-glycogen particles. The body which appears on cross-sections as crest, lateral with respect to the axoneme, is present in both species. Such a body is reported for the first time in Cestode spermatozoa. There is no mitochondrion in the two Onchobothriidae sperms studied.

Animals↗
PubMed1975

[Ultrastructure of nephridial systems in cyclophyllidean cestoda: Catenotaenia pusilla (Goeze, 1782), Hymenolepis diminuta (Rudolphi, 1819) and Inermicapsifer madagascariensis (Davaine, 1870) Baer, 1956].

Electron microscopic study of nephridial systems in three cyclophyllidean cestodes indicates a resemblance in their ultrastructure. The walls of longitudinal, transverse and collecting ducts show a very similar pattern of organization. The surface of the anucleate epithelium lining the ducts is developed into microvilli. A relatively thick layer of fibrillar tissue underlies the basal membrane of the microvillar epithelium. The nucleated portions or "pericaryons", situated between the parenchymal cells, are directly connected with epithelium by cytoplasmic prolongations. The canalicular lumen extends through a single series of cells curved into a ring. The epithelial surface of the canalicular wall is developed into short, densly staining microvilli and the immediately underlying fibrillar tissue appears very compact. The cilia were never observed in any of the above ducts. The ultrastructure of protonephridia proper is comparable with those already described in other cestodes. There is a close association between the flame-cell and the cancalicular ending, enlarged into a nephridial funnel. A single row of nephridial rods of the flame-cell is surrounded by a row of digitiform prolongations of the nephridial funnel border. The prolongations alternate with the rods and their interlocking pattern appears clearly in cross-sections. A series of minute pores or "nephrostomes" providing a direct contact between the nephridial chamber and intercellular space of the paranchyma was shown. The problem of classification and definition between the "closed" protonephridia and open metanephridia is discussed. The structural unity of protonephridia in different groupes of Platyhelminthes is reviewed. The different number of flagella within the "flames" of different cestodes is compared and analyzed. The ultrastructural characteristics of duct-wall epithelium provides some confirmation of its high metabolic activity.

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