Bundles Of Parallel Cortical Microtubules Research Articles

Ultrastructural Characteristics of the Mature Spermatozoon of Artyfechinostomum malayanum (Digenea: Echinostomatidae), an Intestinal Parasite of Rattus norvegicus (Rodentia: Muridae) in Vietnam.

The study of sperm characteristics has proven useful for elucidating interrelationships in several groups of Platyhelminthes, such as digeneans. Thus, in the present work, the ultrastructural organization of the mature spermatozoon of the digenean Artyfechinostomum malayanum (Echinostomatidae), a parasite of Rattus norvegicus (Rodentia: Muridae) from Dong Thap Province, Vietnam, was investigated for the first time using transmission electron microscopy. The male gamete of A. malayanum exhibits two axonemes of different lengths, showing the 9 + '1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two lateral expansions, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies, and granules of glycogen. Thus, the mature spermatozoon follows a Type V sperm model proposed for digeneans. We also highlight some noteworthy characteristics in Echinostomatidae with possible phylogenetic implications, such as two lateral expansions in the anterior region of the spermatozoon and two mitochondria.

Sperm characteristics of the Telorchiidae (Digenea, Plagiorchioidea): First ultrastructural data on Telorchis attenuatus an intestinal parasite of Trachemys scripta elegans

The ultrastructural features of the mature spermatozoon of Telorchis attenuatus (Digenea, Telorchiidae), an intestinal parasite of the red-eared turtle Trachemys scripta elegans (Testudines, Emydidae), are described using transmission electron microscopy (TEM). The mature spermatozoon of T. attenuatus is a filiform cell tapered at both ends and displays Bakhoum et al.’s type IV of digenean sperm cells. Spermatozoa of T. attenuatus have: (i) two axonemes of different lengths with the 9+'1' pattern of trepaxonematan Platyhelminthes, surrounded by a continuous submembranous layer of cortical microtubules at their anterior end, (ii) an external ornamentation of the plasma membrane following Quilichini et al.'s type 2 and associated with cortical microtubules, (iii) two bundles of parallel cortical microtubules with the maximum number situated in the anterior part of the sperm cell, (iv) spine-like bodies, (v) two mitochondria, and (vi) a large number of irregularly distributed glycogen granules. Furthermore, the morphology of the posterior spermatozoon extremity in T. attenuatus corresponds to the Quilichini et al.'s fasciolidean type. The results of the current study are especially compared to the existing information from other families within the superfamily Plagiorchioidea.

Sperm ultrastructural features of Proctotrema bacilliovatum (Digenea, Monorchiidae), an intestinal parasite of the Striped red mullet Mullus surmuletus (Teleostei, Mullidae) from the Gulf of Gabès (Tunisia)

The ultrastructural organisation of the mature spermatozoon of Proctotrema bacilliovatum (Digenea, Monorchioidea, Monorchiidae) is described by means of transmission electron microscopy (TEM). Live digeneans were collected from the digestive tract of the Striped red mullet Mullus surmuletus (Teleostei, Mullidae), caught off from the Gulf of Gabès in La Chebba (Tunisia). The ultrastructural study reveals that the male gamete of P. bacilliovatum is a filiform cell tapered at both extremities and exhibits typical characteristics of digenean sperm such as two 9+'1′ axonemes of different lengths, mitochondria/a, an external ornamentation of the plasma membrane type 2 according to Quilichini et al. (2011) associated with cortical microtubules, spine-like bodies, two bundles of parallel cortical microtubules with their maximum number (around 42 microtubules) located in the anterior part of the spermatozoon and granules of glycogen. Moreover, the spermatozoon of P. bacilliovatum displays the Quilichini et al.’s fasciolidean type of posterior extremity.

First spermatological data on the digenean genus Ityogonimus derived from the description of sperm characters of Ityogonimus ocreatus (Brachylaimidae: Ityogoniminae)

The present study describes the ultrastructural organization of the spermatozoa of the brachylaimid digenean Ityogonimus ocreatus (Ityogoniminae) by means of transmission electron microscopy (TEM). Live digeneans were collected from the digestive tract of an Iberian mole Talpa occidentalis (Eulipotyphla, Talpidae) captured accidentally during a vole pest control campaign in Priesca (Asturias, Spain). The TEM study reveals that the I. ocreatus sperm are filiform, tapered at both extremities, and have two 9+'1' trepaxonematan axonemes, external ornamentation of the plasma membrane associated with cortical microtubules, spine-like bodies, two bundles of parallel cortical microtubules and one mitochondrion overlapping the anterior part of the nucleus. The external ornamentation of the plasma membrane is located in the posterior part of the anterior region. The maximum number of parallel cortical microtubules (45) is located in the anterior part of the sperm cells. Our results are compared with the available data on the family Brachylaimidae, especially on the other Ityogoniminae studied to date (Scaphiostomum palaearcticum).

Spermatological characters in the Lepocreadioidea, with first data on Holorchis pycnoporus (Aephnidiogenidae), a parasite of the Striped seabream Lithognathus mormyrus (Sparidae) from the Gulf of Gabes (Tunisia)

The ultrastructural characteristics of the mature spermatozoon of Holorchis pycnoporus (Digenea, Lepocreadioidea, Aephnidiogenidae) are described by means of transmission electron microscopy (TEM). Live worms were collected from the digestive tract of the Striped seabream Lithognathus mormyrus (Teleostei, Sparidae), off the Gulf of Gabès at La Chebba (Tunisia). The ultrastructural study reveals that the male gamete of H. pycnoporus is a filiform cell tapered at both extremities and exhibiting the type III of the digenean spermatozoon proposed by Bakhoum et al. (2017a), characterized by the presence of (1) two axonemes with the 9 + ‘1’ pattern of the Trepaxonemata, (2) external ornamentation of the plasma membrane located in a posterior part of the anterior region of the spermatozoon and associated with cortical microtubules, (3) two bundles of parallel cortical microtubules with maximum number located in the middle part of the spermatozoon, and (4) generally two mitochondria. Moreover, H. pycnoporus shares a set of ultrastructural characteristics with the studied Aephnidiogenidae such as: (1) two 9+'1' axonemes of different lengths, (2) an anterior electron-dense material, (3) mitochondrion/a, (4) an external ornamentation of the plasma membrane associated with cortical microtubules, and (5) two bundles of parallel cortical microtubules with their maximum number (around 24 microtubules) located in the middle or posterior part of the spermatozoon. In the Aephnidiogenidae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the location of maximum number of cortical microtubules and the number of mitochondria. The presence of the anterolateral electron-dense material is the major particularity in species belonging to the Lepocreadioidea. This anterior dense material could be a synapomorphy for the superfamily and an ultrastructural argument supporting the monophyletic status of the Lepocreadioidea (Bray and Cribb, 2012).

Sperm ultrastructure of Prodistomum polonii (Digenea, Lepocreadioidea), an intestinal parasite of the Atlantic horse mackerel, Trachurus trachurus (Teleostei, Carangidae), from the Gulf of Gabes, Mediterranean Sea

The present study describes the ultrastructural organization of the mature spermatozoon of the lepocreadioid digenean Prodistomum polonii (Lepocreadiidae) by means of transmission electron microscopy (TEM). Live digeneans were collected from the digestive tract of the Atlantic horse mackerel Trachurus trachurus (Teleostei, Carangidae) captured in the coastal zone of the Mediterranean Sea, off La Chebba (Tunisia). The study reveals that the mature sperm cell of P. polonii is a filiform cell, which is tapered at both extremities. It exhibits the Bakhoum et al.’s type III of the digeneans spermatozoon characterized by the presence of: two 9+‘1’ axonemes, external ornamentation of the plasma membrane associated with cortical microtubules and located in the posterior part of the anterior region, two bundles of parallel cortical microtubules with their maximum number (15 microtubules) located in the middle part, and the presence of two mitochondria (one of them of moniliform type). According to the location of the external ornamentation, the male gamete of P. polonii presents a Quilichini et al.’s type 2 spermatozoon. Moreover, in the anterior spermatozoon extremity, there is a discontinuous and submembranous layer of electron-dense material. Whereas, the posterior spermatozoon extremity belongs to the Quilichini et al.’s cryptogonimid type. Our results are compared with the available data on digenean spermatology, in particular with species belonging to the superfamily Lepocreadioidea to highlight the potential criteria useful for phylogeny.

Sperm characters of the digenean Nephrotrema truncatum (Troglotrematidae): a kidney parasite of Crocidura russula (Soricidae) and their phylogenetic significance

ABSTRACTSpermatological characteristics of the troglotrematid digenean Nephrotrema truncatum, a parasite of the shrew Crocidura russula, have been investigated by means of transmission electron microscopy. The ultrastructural study reveals that the mature spermatozoon of N. truncatum exhibits many ultrastructural characters previously described in most gorgoderoideans. These are two axonemes of the 9+‘1‘ trepaxonematan pattern, four attachment zones, a lateral expansion, an external ornamentation of the plasma membrane associated with spine-like bodies and cortical microtubules, and in the posterior part of the anterior spermatozoon region, two bundles of parallel cortical microtubules with the maximum number located in the anterior part of the spermatozoon, a nucleus, two mitochondria, and granules of glycogen. The obtained results are compared with those of other digeneans, particularly the Gorgoderoidea. The sperm cells gorgoderoideans are of type IV, characterised by a 9+‘1‘ pattern of axonemes, the presence of an external ornamentation associated with cortical microtubules and located in the posterior area of the anterior extremity, the presence of two bundles of cortical microtubules, the maximum number of cortical microtubules located in the anterior region of the spermatozoon, and the presence of generally two mitochondria. However, dicrocoeliids and troglotrematids have spermatozoa with ornamentation of the plasma membrane and lateral expansions.

Spermatological characteristics of Siphoderina aloysiae (Digenea, Cryptogonimidae), an intestinal parasite of Sciaena umbra (Teleostei, Sciaenidae)

The ultrastructural organisation of the spermatozoon of Siphoderina aloysiae (Digenea, Cryptogonimidae) is described based upon examination by transmission electron microscopy. Live digeneans were collected from the digestive tract of the Brown meagre Sciaena umbra (Teleostei: Sciaenidae), caught off the Gulf of Gabes in La Chebba (Tunisia). The male gamete of S. aloysiae is a filiform cell, tapered at both extremities, and exhibits typical characteristics of digenean sperm such as two axonemes showing the 9 + ‘1’ trepaxonematan pattern with different lengths. The first axoneme is disorganised and disappears near the anterior nuclear extremity. However, the second axoneme reaches the posterior extremity of the spermatozoon. The latter also contains a nucleus, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies and granules of glycogen. Cortical microtubules are absent in the anterior extremity of the spermatozoon and appear after the disappearance of the electron-dense material. In addition, the male gamete of S. aloysiae has two mitochondria. The first mitochondrion is associated with the external ornamentation of the plasma membrane and spine-like bodies. The second is more posteriorly located at the nuclear region after the disappearance of the first axoneme. The present study provides new data on the mature male gamete of S. aloysiae that may be useful for the understanding of digenean relationships and phylogenetic studies.

Reinvestigation of the sperm ultrastructure of Hypoderaeum conoideum (Digenea: Echinostomatidae).

Spermatological characteristics of the digenean Hypoderaeum conoideum (Echinostomatidae) collected from Anas platyrhynchos in the Lac d'Annecy (France) were reinvestigated using transmission electron microscopy. The previous study on this species only describes the presence of two axonemes of unequal lengths, a mitochondrion, a posterior nucleus, and the disposition of cortical microtubules. The present ultrastructural study reveals that the mature spermatozoon of H. conoideum is a filiform cell tapered at both extremities. The sperm cell exhibits the characteristics of a digenean spermatozoa type V, namely two axonemes of the 9 + '1' pattern of trepaxonematan Platyhelminthes, external ornamentation of the plasma membrane associated with cortical microtubules, and located in the anterior part of the proximal region of the sperm cell, lateral expansions, two bundles of parallel cortical microtubules, maximum number of cortical microtubules in the anterior part of the spermatozoon, and presence of two mitochondria. In addition, the sperm cell of H. conoideum shows spine-like bodies and a posterior extremity with only the nucleus. The ultrastructural characters of the spermatozoon of H. conoideum are compared with those of other digeneans belonging to the superfamily Echinostomatoidea.

Ultrastructure of the spermatozoon of Aephnidiogenes senegalensis (Digenea, Aephnidiogenidae), an intestinal parasite of Pomadasys jubelini (Teleostei, Haemulidae) off the coast of Dakar (Senegal)

This study provides the first ultrastructural data on the mature spermatozoon of Aephnidiogenes senegalensis (Digenea, Lepocreadioidea, Aephnidiogenidae) parasite of the teleost fish Pomadasys jubelini (Haemulidae) captured near the coast of Dakar (Senegal). This is also the first ultrastructural data on the spermatozoon in the genus Aephnidiogenes. The mature spermatozoon of A. senegalensis is filiform, tapered at both ends and exhibits the general pattern described in the Lepocreadioidea, namely two axonemes of the 9 + ‘1’ pattern, an antero-lateral electron dense material, a nucleus, two mitochondria, external ornamentation of the plasma membrane in the anterior region of the spermatozoon, granules of glycogen and two bundles of parallel cortical microtubules. A peculiarity of the spermatozoon of A. senegalensis is the structure of the apical electron-dense material.

Sperm characters of the bucephalid digenean Prosorhynchoides arcuatus and their phylogenetic significance

The present study describes the ultrastructural organisation of the mature spermatozoon of the bucephalid digenean Prosorhynchoides arcuatus (Bucephalinae) collected from the Bluefish Pomatomus saltatrix (Teleostei: Pomatomidae) caught from the Gulf of Gabès in the Chebba (Tunisia) by means of transmission electron microscopy. The ultrastructural study reveals that the mature spermatozoon of P. arcuatus is a filiform cell which is tapered at both extremities. It exhibits the Bakhoum et al.’s type V of spermatozoon of digeneans characterised by the presence of two axonemes with the 9+‘1’ pattern of the Trepaxonemata, lateral expansion, external ornamentation of the plasma membrane located in the anterior part of the proximal region of the spermatozoon and associated with cortical microtubules, two bundles of parallel cortical microtubules with maximum number located in the anterior part of the spermatozoon, and one mitochondrion. Other characteristics are the presence of spine-like bodies, a posterior extremity containing only the nucleus, and the presence of a large amount of glycogen granules. Results of the present study are compared with the existing data in other digeneans, particularly bucephalids.

Sperm characters of Timoniella imbutiforme (Digenea, Opisthorchioidea, Cryptogonimidae), a parasite of the European seabass Dicentrarchus labrax

Spermatological characteristics of the digenean Timoniella imbutiforme (Cryptogonimidae) collected from Dicentrarchus labrax (Teleostei: Serranidae) collected at the Gulf of Gabès in Chebba (Tunisia) were investigated for the first time by means of transmission electron microscopy. The ultrastructural study reveals that the mature spermatozoon of T. imbutiforme is a filiform cell, tapered at both extremities. The sperm cell exhibits the characteristics of digenean spermatozoa type IV namely two axonemes of the 9+‘1’ pattern of trepaxonematan Platyhelminthes, external ornamentation of the plasma membrane associated with cortical microtubules and located in the posterior part of the anterior region of the sperm cell, two bundles of parallel cortical microtubules, maximum number of cortical microtubules in the anterior part of the spermatozoon and presence of two mitochondria. The first mitochondrion of moniliform type is composed of a mitochondrial cord with joined mitochondrial bulges. In addition, the male gamete of T. imbutiforme shows spine-like bodies and a posterior extremity with only the second axoneme. The ultrastructural characters of the spermatozoon of T. imbutiforme are compared with those of other digeneans belonging to the superfamily Opisthorchioidea.

Ultrastructure of the spermatozoon of Macvicaria obovata (Digenea: Opecoelidae), a parasite of Sparus aurata(Pisces: Teleostei) from the Gulf of Gabès, Mediterranean Sea.

The ultrastructural organization of the spermatozoon of the digenean Macvicaria obovata (Opecoelidae) is described by transmission electron microscopy. Alive digeneans were collected from the digestive tract of Sparus aurata (Teleostei, Sparidae), caught from the Gulf of Gabès in Chebba, Tunisia (Eastern Mediterranean Sea). The male gamete of M. obovata is a filiform cell, tapered at both extremities and exhibits typical characters such as two axonemes of different lengths showing the 9+'1' trepaxonematan pattern, a nucleus, mitochondria, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies and granules of glycogen. Cortical microtubules are absent in the anterior spermatozoon extremity and appear after the disappearance of the electron-dense material. The first mitochondrion is of moniliform type and it is associated with the external ornamentation of the plasma membrane and spine-like bodies. The second mitochondrion is more posteriorly located, reaching the nuclear region. The present study provides new data on the mature male gamete of M. obovata that may be useful for the understanding of digenean relationships and phylogenetic studies.

Spermatozoon ultrastructure in two monorchiid digeneans.

Spermatological characteristics of species from two monorchiid genera, Opisthomonorchis and Paramonorcheides, have been investigated, for the first time, by means of transmission electron microscopy. The ultrastructural study reveals that the mature spermatozoon of Opisthomonorchis dinema and Paramonorcheides selaris share several characters such as the presence of two axonemes of different lengths showing the 9+“1” pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies, granules of glycogen and similar morphologies of the anterior and posterior extremities. The slight differences between the male gamete of O. dinema and P. selaris are the length of the first axoneme and the position of the second mitochondrion. This study also elucidates the general morphology of the spermatozoon in all monorchiid species described so far, which corresponds to a unique spermatozoon type. Other interesting finds concern the spermatological similarities between monorchiid spermatozoa and the mature spermatozoon reported in the apocreadiid Neoapocreadium chabaudi. These similarities allow us to suggest a close phylogenetical relationship between the Monorchiidae and the Apocreadiidae, although more studies are needed, especially in the unexplored taxa.

Sperm ultrastructure of Podocotyloides magnatestis (Digenea, Opecoeloidea, Opecoelidae) a parasite of Parapristipoma octolineatum (Pisces, Teleostei)

The mature Podocotyloides magnatestis spermatozoon exhibits two axonemes of the 9+“1” pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, spine-like bodies, an external ornamentation of plasma membrane, glycogen granules and an antero-lateral electron-dense material. These ultrastructural characteristics have already been described in the Opecoeloidea species studied so far. However, P. magnatestis spermatozoon is distinguished by the fact that its electron-dense material is laterally located on the side of the second axoneme. Moreover, the posterior spermatozoon extremity, characterized by the presence of the nucleus, is observed for the first time in the Opecoelidae.

Spermatological characters of the digenean Lecithostaphylus retroflexus (Molin, 1859) (Microphalloidea: Zoogonidae), a parasite of the teleost fish Belone belone gracilis.

The ultrastructural organization of the spermatozoon of the digenean Lecithostaphylus retroflexus (Microphalloidea: Zoogonidae) was described. Alive digeneans were collected from Belone belone gracilis (Teleostei: Belonidae), caught from the Gulf of Gabès in Chebba (Tunisia). The mature spermatozoon of L. retroflexus exhibits two axonemes of different lengths with the 9+'1' Trepaxonematan pattern, a nucleus, two mitochondria, two bundles of parallel cortical microtubules and granules of glycogen. Additionally, the spermatozoon of L. retroflexus shows type 2 of the external ornamentation according to Quilichini et al. (2011), spine-like bodies and a continuous and submembranous layer of parallel cortical microtubules surrounding the axonemes at their anterior end. Moreover, the morphology of the posterior spermatozoon extremity in L. retroflexus corresponds to the fasciolidean type according to Quilichini et al. (2010).

Ultrastructure of the spermatozoon of the digenean Tergestia acanthocephala (Stossich, 1887) (Gymnophalloidea: Fellodistomidae): An intestinal parasite of Belone belone gracilis (Pisces: Teleostei).

The ultrastructural organization of the spermatozoon of the digenean Tergestia acanthocephala (Gymnophalloidea: Fellodistomidae) is described. Live digeneans were collected from Belone belone gracilis (Teleostei: Belonidae), caught off the Gulf of Gabès in Chebba (Tunisia). The mature spermatozoon of T. acanthocephala exhibits the general pattern described in numerous digeneans, characterized by the presence of two axonemes of the different length of the 9+'1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies and granules of glycogen. Moreover, the morphology of the posterior spermatozoon extremity in T. acanthocephala corresponds to the fasciolidean type of Quilichini et al. (2010a).

Neomultitestis aspidogastriformis Bray and Cribb, 2003 (Digenea, Lepocreadiidae): mature spermatozoon and sperm morphologies in the Lepocreadioidea

Spermatological characteristics are described for the first time in the genus Neomultitestis Machida, 1982, belonging to the family Lepocreadiidae Odhner, 1905. Adult Neomultitestis aspidogastriformis were collected from the digestive tract of Platax teira, caught off New Caledonia. The mature spermatozoon of N. aspidogastriformis is described by transmission electron microscopy (TEM). It includes two axonemes with 9 + "1" pattern of Trepaxonemata, an antero-lateral electron-dense material, attachment zones, two mitochondria, a nucleus, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies, and granules of glycogen. Certain ultrastructural characteristics of the spermatozoon, especially the antero-lateral electron-dense material, are shared by N. aspidogastriformis and all species of the superfamily Lepocreadioidea studied so far. The antero-lateral electron-dense material, present in different families of lepocreadioids, supports the monophyletic status of the superfamily. We also list several ultrastructural characteristics which characterize the mature spermatozoon of the Lepocreadioidea.

Ultrastructural study of sperm cells in Acanthocolpidae: the case of Stephanostomum murielae and Stephanostomoides tenuis (Digenea).

The mature spermatozoa of Stephanostomum murielae and Stephanostomoides tenuis are described by transmission electron microscopy. They present several ultrastructural features previously reported in other digeneans. Their spermatozoa possess two axonemes of different length showing the 9 + ‘1’ trepaxonematan pattern, four attachment zones, two mitochondria (with an anterior moniliform one in S. murielae), a nucleus, two bundles of parallel cortical microtubules, external ornamentation of the plasma membrane, spine-like bodies and granules of glycogen. The main differences between the mature spermatozoon of S. murielae and S. tenuis are the maximum number of cortical microtubules, the morphology of the anterior spermatozoon extremity and the anterior mitochondrion. This study is the first concerning members of the family Acanthocolpidae. The main ultrastructural characteristics discussed are the morphology of the anterior and posterior spermatozoon extremities, antero-lateral electron dense material, external ornamentations, spine-like bodies and number and morphology of mitochondria. In addition, the phylogenetic significance of all these ultrastructural features is discussed and compared to molecular results in order to highlight the complex relationships in the Digenea.

Ultrastructure of the male gamete of Brachylecithum eliomydis (Digenea, Dicrocoeliidae)—A parasite of Eliomys quercinus (Rodentia, Gliridae)

The male gametes of Brachylecithum eliomydis (Digenea, Dicrocoeliidae) a parasite of Eliomys quercinus “the garden dormouse” caught in France were described by micrographs of transmission electron microscopy (TEM). The mature spermatozoon of B. eliomydis presents classical characteristics early described in digenean species such as the two axonemes of different lengths with the 9+“1” pattern of the trepaxonematan platyhelminthes, two bundles of parallel cortical microtubules, two mitochondria, a nucleus and granules of glycogen. Moreover, several characteristics, described in the spermatozoon of B. eliomydis, vary within digenean taxa. Those are (1) the morphology of anterior and posterior spermatozoon extremities, (2) the external ornamentation of the plasma membrane and its association or not with cortical microtubules, (3) the presence or absence of spine-like bodies and (4) the number of cortical microtubules and their organization into one or two parallel bundles. Using these four criteria, the morphology of the mature spermatozoon of B. eliomydis was compared to that of the other dicrocoellids, brachycoeliids, paragonimids and troglotrematids species described so far. The general morphology of the spermatozoon described in B. eliomydis, could characterize the family Dicrocoeliidae.