Dicrocoelium hospes Looss, 1907 (Digenea, Dicrocoeliidae): spermiogenesis, mature spermatozoon and ultrastructural comparative study

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The ultrastructure of spermiogenesis in Wenyonia virilis Woodland, 1923, a caryophyllaeid cestode from the silurid Nile fish Synodontis schall (Bloch et Schneider, 1801), is described by means of transmission electron microscopy (TEM) for the first time. Spermiogenesis follows the characteristic caryophyllidean type and is initiated by the formation of a differentiation zone. This area, delimited at its base by a ring of arching membranes and bordered by cortical microtubules, contains two centrioles associated with typical striated rootlets with a reduced intercentriolar body between them. The apical area of the differentiation zone exhibits electron-dense material that is present only during the early stages of spermiogenesis. Only one of the centrioles develops into a free flagellum that grows at an angle of >90° in relation to the cytoplasmic extension. Spermiogenesis is also characterized by a flagellar rotation and a proximodistal fusion of the flagellum with the cytoplasmic extension. The most interesting features observed in W. virilis are the presence of a reduced, very narrow intercentriolar body and the unique type of flagellar rotation >90°. Results are compared with those described in two caryophyllideans, Glaridacris catostomi Cooper, 1920 and Khawia armeniaca (Cholodkovski, 1915). Contrary to the original report of OEwiderski and Mackiewicz (2002), that flagellar rotation has never been observed in spermiogenesis of G. catostomi, re-assessment of their description and illustrations leads us to conclude that flagellar rotation must logically occur in that species. The value of various morphological features of sperm in phylogenetic inference is discussed.

Section: Discussionmentioning

confidence: 91%

Ultrastructure of spermiogenesis in the caryophyllidean cestode Wenyonia virilis Woodland, 1923, with re-assessment of flagellar rotation in Glaridacris catostomi Cooper, 1920

Miquel

Świderski²,

Mackiewicz

et al. 2008

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“…This is also the case for T. taeniaeformis. Taking into account the recent observations of flagellar rotations of up to 120°in the Fasciolidae, Dicrocoeliidae, Monorchiidae, Opecoelidae and Allocreadiidae digeneans (Ndiaye et al 2003c;Levron et al 2003Levron et al , 2004Agostini et al 2005;Quilichini et al 2007a, b), and described in the caryophyllidean Wenyonia virilis and in the spathebothriidean C. truncatus (Bruňanská et al 2006, Miquel et al 2008), it appears that there may be a gradual reduction of the rotation angle until there is no rotation, a state that is considered the apomorphic condition of this character (Justine 1998(Justine , 2001.…”

Section: Spermiogenesismentioning

confidence: 95%

Ultrastructure of spermatogenesis of Taenia taeniaeformis (Batsch, 1786) (Cestoda, Cyclophyllidea, Taeniidae) and comparison of spermatological characters in the family Taeniidae Ludwig, 1886

Miquel

Świderski²,

Foronda³

et al. 2009

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The ultrastructure of spermatogenesis of Taenia taeniaeformis is described for the first time by means of transmission electron microscopy (TEM). Mature testes contain all stages of spermatogenesis; primary spermatogonia are usually situated at the periphery and mature spermatozoa in the centre of testes. The general process is similar to that described in other cestodes. Six incomplete, synchronic cytokineses occur: four mitotic and two meiotic cell divisions. All these divisions occur simultaneously, resulting in a rosette cluster of four tertiary spermatogonia, then eight quaternary spermatogonia, and subsequently sixteen primary spermatocytes. All of these enter into a growth period and their enlarged nuclei move to the periphery of cells of the rosettes. The first meiotic division forms thirty-two secondary spermatocytes and after the second meiotic division, there are sixty-four spermatids. Spermiogenesis in T. taeniaeformis corresponds to the Bâ and Marchand's Type 3 and begins with the formation of a differentiation zone in the form of a conical projection of cytoplasm delimited by a ring of arching membranes and surrounded by submembranous cortical microtubules. Within this area, there are two centrioles, orthogonally disposed, and vestigial striated rootlets. Only one of the centrioles develops a flagellum that grows externally to the cytoplasmic extension. Posteriorly, a flagellar rotation inferior to 90º occurs and the flagellum becomes parallel to the cytoplasmic extension. Later, the two processes fuse during the so-called proximodistal fusion. The nucleus elongates and moves into the cytoplasmic extension. In the final stage of spermiogenesis, a single crested body appears at the base of the differentiating spermatozoon. Finally, the ring of arching membranes constricts and the young spermatozoon detaches from the residual cytoplasm. Ultrastructural aspects of spermatogenesis are compared with that of other cestodes studied to date, particularly of the family Taeniidae.

“…Other digeneans exhibit two mitochondria, one being located at the level of the ornamented region and the other in the area containing the nucleus. This is the case of the opecoelids P. furcatum, N. wisniewskii, N. testiobliquum (Levron et al 2004b;Quilichini et al 2007a, c), the dicrocoeliid D. hospes (Agostini et al 2005), the troglotrematid T. acutum (Miquel et al 2006), the apocreadiid N. chabaudi (Kacem et al 2010) or the omphalometrid R. exasperatum (Bakhoum et al 2011b). Additionally, a spermatozoon with three mitochondria has recently been described in B. ectorchus, S. sudanensis, A. capitellatum and E. squamula (Ashour et al 2007, Bakhoum et al 2009, Ternengo et al 2009).…”

Section: Spermatozoonmentioning

confidence: 98%

“…However, some recent studies have described flagellar rotations greater than 90°. It is the case of Helicometra fasciata, Monorchis parvus, Fasciola hepatica, Dicrocoelium hospes, Nicolla wisniewskii or Crepidostomum metoecus (Ndiaye et al 2003;Levron et al 2003Levron et al , 2004aAgostini et al 2005;Quilichini et al 2007a, b).…”

Section: Spermiogenesismentioning

confidence: 99%

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Spermiogenesis and ultrastructure of the spermatozoon of Wardula capitellata (Digenea, Mesometridae), an intestinal parasite of the sparid teleost Sarpa salpa in Senegal

Bakhoum¹,

Ndiaye

Sène

et al. 2012

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The spermiogenesis process in Wardula capitellata begins with the formation of a differentiation zone containing two centrioles associated with striated rootlets and an intercentriolar body. Each centriole develops into a free flagellum orthogonal to a median cytoplasmic process. Later these flagella rotate and become parallel to the median cytoplasmic process, which already exhibits two electron-dense areas and spinelike bodies before its proximodistal fusion with the flagella. The final stage of the spermiogenesis is characterized by the constriction of the ring of arched membranes, giving rise to the young spermatozoon, which detaches from the residual cytoplasm. The mature spermatozoon of W. capitellata presents most of the classical characters reported in digenean spermatozoa such as two axonemes of different lengths of the 9 + "1" trepaxonematan pattern, nucleus, mitochondrion, two bundles of parallel cortical microtubules and granules of glycogen. However, some peculiarities such as two lateral expansions accompanied by external ornamentation of the plasma membrane and spinelike bodies characterize the mature sperm. Moreover, a new spermatological character is described for the first time, the so-called cytoplasmic ornamented buttons.