Spermatozoon Axis Research Articles

Ultrastructure of the spermatozoon of Anomotaenia quelea (Mettrick, 1961) (Cestoda, Cyclophyllidea, Dilepididae), an intestinal parasite of Quelea quelea (Aves, Ploceidae) in Senegal

The mature spermatozoon of Anomotaenia quelea exhibits an apical cone of electron-dense material and two helicoidal crest-like bodies. The apical cone near its base is surrounded by a lucent cytoplasm and a spiraled layer of cortical microtubules. The crest-like bodies are of different lengths, spiraled and make an angle of 30–40° to the hypothetical spermatozoon axis. The axoneme is of the 9+‘1’ trepaxonematan pattern and is surrounded by a periaxonemal sheath of electron-dense material. The cytoplasm contains in regions III and IV numerous electron-dense granules situated between the periaxonemal sheath and the cortical microtubules. The posterior extremity of the spermatozoon of A. quelea exhibits a nucleus and a disorganized axoneme and cortical microtubules. This type of posterior extremity of the mature spermatozoon has never been described previously in a Dilepididae. Similarly, two crest-like bodies have not been observed before in a dilepidid cestode.

Ultrastructure of spermiogenesis and mature spermatozoon of Triaenorhina rectangula (Cestoda: Cyclophyllidea: Paruterinidae)

Ultrastructural characters of spermiogenesis and mature spermatozoon of Triaenorhina rectangula (Fuhrmann, 1908) are examined by transmission electron microscopy. Spermiogenesis follows the Bâ and Marchand's Type III spermiogenesis of cestodes. The process begins with the formation of a differentiation zone containing two centrioles and a cytoplasmic protrusion. The centrioles are associated with vestigial striated roots. One of the centrioles develops a free flagellum externally to the cytoplasmic protrusion. After a slight rotation, the free flagellum fuses with the cytoplasmic protrusion. In the final stage of spermiogenesis, a single crested body appears in the anterior part of the differentiating spermatozoon. The anterior extremity of the mature spermatozoon is characterised by an apical cone and a single crested body. The axoneme is of the 9+"1" trepaxonematan type. A periaxonemal sheath and electron-dense rods are described in some parts of the mature spermatozoon. The nucleus is electron-dense and spirally coiled around the axoneme. The cortical microtubules are spirally arranged at an angle of about 40 degrees to the spermatozoon axis. The present results show that the ultrastructural characters of spermiogenesis and mature spermatozoon of T. rectangula resemble most closely those in taeniids and metadilepidids. The comparison of these results with the only previous spermiological description of a paruterinid species reveals differences relative to the occurrence of filamentous rods of electron-dense material versus intracytoplasmic walls in the mature spermatozoon that may reflect the polyphyletic character of the Paruterinidae.

Spermiogenesis and sperm ultrastructure of Valipora mutabilis Linton, 1927 (Cestoda, Cyclophyllidea, Gryporhynchidae)

This is the first ultrastructural study of the spermiogenesis and the mature spermatozoon of a cyclophyllidean cestode of the family Gryporhynchidae. The spermiogenesis of Valipora mutabilis begins with the formation of a differentiation zone delimited by arching membranes and containing two centrioles. One of the centrioles develops an axoneme that grows directly into the cytoplasmic protrusion. The other centriole remains situated in a cytoplasmic bud and is subsequently aborted (type IV of cestode spermiogenesis). The mature spermatozoon of V. mutabilis is a filiform cell, tapered at both extremities and lacks mitochondria. The anterior extremity is characterised by the presence of an apical cone and a single helicoidal crested body. The axoneme is of 9 + '1' trepaxonematan pattern, with a periaxonemal sheath. The cortical microtubules are twisted at an angle of about 45 degrees to the spermatozoon axis. The nucleus is electron dense and spirally coiled around the axoneme. The cytoplasm is electron lucent and contains numerous granules of electron-dense material. In contrast to a recent opinion for close phylogenetic relationships, these ultrastructural data demonstrate the distant position between gryporhynchids and the family Taeniidae. The most similar pattern in the ultrastructure of the spermiogenesis and the mature spermatozoon has been described for dilepidids, some hymenolepidids and some anoplocephalids.

Ultrastructure of the spermatozoon of Bothriocephalus claviceps (Cestoda, Pseudophyllidea): a parasite of Anguilla anguilla (Fish, Teleostei)

The mature Bothriocephalus claviceps spermatozoon is filiform and tapered at both extremities. It contains two axonemes of unequal lengths of the 9+"1" pattern of the trepaxonemata. The anterior extremity exhibits an apical cone of an electron-dense material about 6.6 microm long by 0.2 microm wide at its base and a crest-like body making an angle of about 40 degrees with the spermatozoon axis. It is spiralized around the whole extremity of the spermatozoon. The nucleus is a cord of electron-dense material that interposes itself between the two axonemes. The cortical microtubules are of two types: hollow-centred and electron-dense centred. The cytoplasm is slightly electron dense and contains numerous electron-dense granules in regions III, IV, and V of the spermatozoon. The anterior and posterior extremities of the spermatozoon contain a single axoneme. The presence of an apical cone of the electron dense material has never, to our knowledge, been reported in the Pseudophyllidea. In addition, we show for the first time the existence of a crested body in the Bothriocephalidae.

Ultrastructure of spermiogenesis and mature spermatozoon of Angularella beema (Clerc, 1906) (Cestoda, Cyclophyllidea, Dilepididae)

AbstractThe ultrastructure of the spermiogenesis of a dilepidid cestode species is described for the first time. The spermiogenesis of Angularella beema is characterised by absence of both flagellar rotation and proximodistal fusion. The differentiation zone is surrounded by cortical microtubules and is delimited by a ring of arching membranes. It contains two centrioles, one of which develops the axoneme that grows directly into the elongating cytoplasmic protrusion. This pattern of spermiogenesis was described as the Type IV spermiogenesis of cestodes. Among cestodes, similar pattern of spermiogenesis is known in the family Hymenolepididae and in some representatives of the family Anoplocephalidae. The mature spermatozoon of A. beema consists of five regions differing in their ultrastructural characteristics. It is characterised by the presence of cortical microtubules (spirally arranged at angle of 30–40° to the spermatozoon axis) and a single crested body. There is a periaxonemal sheath in certain parts of the spermatozoon as well as glycogen-like granules between the periaxonemal sheath and the cortical microtubules. The comparisons of the mature spermatozoon of A. beema with those of other two dilepidid species (Dilepis undula and Molluscotaenia crassiscolex) demonstrate some variation within the family: presence of periaxonemal sheath in A. beema and D. undula and its absence in M. crassiscolex; presence of electron-dense rods in D. undula and their absence in A. beema.

Spermiogenesis and sperm ultrastructure of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781)

Spermiogenesis and ultrastructure of the spermatozoon of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781), a parasite of pike Esox lucius, has been studied by transmission electron microscopy. Spermiogenesis involves firstly the formation of a zone of differentiation with two centrioles associated with striated roots, and an intercentriolar body between them, subsequent growth of the two flagella of unequal length, and a formation of a median cytoplasmic process exhibiting patches of dense material. The nucleus penetrates into spermatid body after flagellar rotation and proximo-distal fusion has started. The mature spermatozoon of T. nodulosus is filiform and contains two axonemes of 9+"1" pattern of the Trepaxonemata, nucleus, cortical microtubules parallel to the spermatozoon axis, and electron-dense granules. The anterior extremity of the gamete contains a single centriole surrounded by numerous electron-dense tubular structures exhibiting spiral arrangement and giving rise to lateral projections, which correspond to the crested body. When the crested body disappears, the spiral pattern of electron-dense tubular structures is changed into a ring, persisting until the centriole of the second axonemes appears. This structure of the crested body of T. nodulosus is unique among the Eucestoda.

Ultrastructure of the spermatozoon of Raillietina (Raillietina) baeri (Cyclophyllidea, Davaineidae) an intestinal parasite of the multimammate rat, Mastomys huberti (Rodentia, Muridae)

The mature Raillietina (Raillietina) baeri spermatozoon exhibits an apical cone of electron-dense material about 2.5 microm long and 0.5 microm wide and two helicoidal crest-like bodies roughly 100-125 nm thick. The latter are of different lengths, spiralized and stand in an angle of about 50 degrees with the spermatozoon axis. The axoneme is of the 9 + "1" pattern and does not reach the posterior extremity of the gamete. The nucleus is an electron-dense cord coiled in a spiral around the axoneme. The cytoplasm exhibits a posterior densification and contains few small electron-dense granules in regions I, II and V of the spermatozoon. In regions III and IV, it is divided into irregular compartments by walls of electron-dense material. The cortical microtubules are spiralized and make an angle of 40-50 degrees to the spermatozoon axis. In this work, we describe, for the first time, a spermatozoon of a davaineidaean cestode parasitic of mammals. This has enabled us to show a wide apical cone, which has never been described before in a cyclophyllidean species the spermatozoon of which has two crest-like bodies.

Ultrastructure of spermiogenesis and the spermatozoon in the genus Joyeuxiella Fuhrmann, 1935 (Cestoda, Cyclophyllidea, Dipylidiidae): comparative analysis of J. echinorhynchoides (Sonsino, 1889) and J. pasqualei (Diamare, 1893)

This paper describes the ultrastructure of spermiogenesis and the mature spermatozoon of two Dipylidiidae cestodes, Joyeuxiella echinorhynchoides and J. pasqualei. In both species, spermiogenesis follows the type III described by Bâ and Marchand for the cyclophyllideans. Nevertheless, it is interesting to note the presence of striated roots associated with the centrioles. The spermatozoon presents the same ultrastructural features in J. echinorhynchoides and J. pasqualei. The apical cone in the anterior extremity of the sperm is more than 2.0 microm long in both J. echinorhynchoides and J. pasqualei. Both species present a single crest-like body, 150 nm thick in J. echinorhynchoides and 75 nm thick in J. pasqualei. The cortical microtubules are spiralled at an angle of 40-45 degrees to the spermatozoon axis in both Joyeuxiella species. A periaxonemal sheath and glycogen granules are also described in the mature sperm. We also describe, for the first time, the disposition of glycogen granules in two opposed and spiralled cords in cestodes and the formation of the periaxonemal sheath in the final stage of spermiogenesis.

Ultrastructure of the spermatozoon of the proteocephalidean cestode Proteocephalus torulosus (Batsch, 1786).

The fine structure of the mature spermatozoon of the proteocephalidean tapeworm Proteocephalus torulosus, a parasite of cyprinid fishes, was studied by transmission electron microscopy for the first time. The mature spermatozoon of P. torulosus is filiform and tapered at both extremities. It contains two axonemes of the 9+"1" type and of unequal length. The anterior extremity of the spermatozoon bears a helicoidal crested body approximately 100 nm thick. Cortical microtubules of two types lie parallel to the spermatozoon axis. The nucleus is a fine cord of condensed chromatin. The slightly electron-dense cytoplasm contains electron-dense granules in regions II and III of the spermatozoon. The anterior and posterior extremities of the spermatozoon contain a single axoneme. The mature spermatozoon of P. torulosus differs from that of other Proteocephalusspecies in the presence of a single crested body and in the morphology of its posterior end.

Ultrastructure of the spermatozoon of the pseudophyllidean cestode Eubothrium crassum (Bloch, 1779).

The fine structure of the mature spermatozoon of the pseudophyllidean tapeworm Eubothrium crassum, a parasite of salmonid fishes, has been studied by transmission electron microscopy for the first time. The mature spermatozoon of E. crassum is filiform and tapered at both extremities. It contains two axonemes of unequal length showing the 9 + "1" pattern of Trepaxonemata. The anterior extremity exhibits a crested body 50-100 nm thick. It spirals around the outside of the anterior region of the spermatozoon. The nucleus is electron-dense, exhibiting a fibrous appearance in its middle (the broadest) region. The cortical microtubules are of two types and are situated parallel to the spermatozoon axis. The cytoplasm is slightly electron-dense and contains numerous electron-dense granules in region II of the spermatozoon. A ring of electron-dense, centred microtubules surrounds the axoneme, together with the underlying ring of moderately electron-dense, subjacent submicrotubular material in region V. The anterior and posterior extremities of the spermatozoon lack cortical microtubules and contain a single axoneme. Our results reveal several peculiarities, in which the spermatozoon of E. crassum differs from those of other pseudophyllidean cestodes.

Sperm ultrastructure of Taenia mustelae (Cestoda, Taeniidae), an intestinal parasite of the weasel, Mustela nivalis (Carnivora)

Summary The present paper describes the ultrastructure of spermatozoa of Taenia mustelae as revealed by transmission electron microscopy. The mature spermatozoon of this tenid is filiform, tapered at both ends, and lacks mitochondrion. It is capped by an apical cone of electron-dense material and presents a single helical crest-like body 75-nm thick. The axoneme is of the 9+‘1’ pattern of trepaxonematan platyhelminthes and lacks a periaxonemal sheath. Transverse intracytoplasmic walls are observed in several regions of the spermatozoon. In cross-section, the spiralled nucleus shows a horse-shoe to annulus shape. The submembranous cortical microtubules are spiralled at an angle of about 45° to the hypothetical spermatozoon axis.

Ultrastructural study of spermiogenesis and the spermatozoon in Catenotaenia pusilla, an intestinal parasite of Mus musculus

The ultrastructure of spermiogenesis and the mature spermatozoon in Catenotaenia pusilla (Cestoda: Catenotaeniidae) is described. Spermiogenesis is characterized by the presence of a single axoneme which grows on the outside of a cytoplasmic extension at an angle of 45 degrees. Flagellar rotation and proximodistal fusion are produced in this process. The centrioles lack striated roots and an intercentriolar body. In the mature spermatozoon four different regions are described. The anterior extremity is capped by an apical cone and presents two helical crest-like bodies of unequal length. The axoneme, of the 9 + '1' pattern of the Trepaxonemata, presents a periaxonemal sheath. The cortical microtubules form a spiral pattern at an angle of about 40 degrees to the hypothetical spermatozoon axis. The nucleus is kidney- to horseshoe-shaped in cross section. Granules and proteinaceus walls are not observed in the spermatozoon of C. pusilla.

Ultrastructural study of spermiogenesis and the spermatozoon in Catenotaenia pusilla, an intestinal parasite of Mus musculus

AbstractThe ultrastructure of spermiogenesis and the mature spermatozoon in Catenotaenia pusilla (Cestoda: Catenotaeniidae) is described. Spermiogenesis is characterized by the presence of a single axoneme which grows on the outside of a cytoplasmic extension at an angle of 45°. Flagellar rotation and proximodistal fusion are produced in this process. The centrioles lack striated roots and an intercentriolar body. In the mature spermatozoon four different regions are described. The anterior extremity is capped by an apical cone and presents two helical crest-like bodies of unequal length. The axoneme, of the 9 + ‘1’ pattern of the Trepaxonemata, presents a periaxonemal sheath. The cortical microtubules form a spiral pattern at an angle of about 40° to the hypothetical spermatozoon axis. The nucleus is kidney- to horseshoe-shaped in cross section. Granules and proteinaceus walls are not observed in the spermatozoon of C. pusilla.

Ultrastructure of Spermiogenesis and the Spermatozoon of Anoplocephaloides dentata (Cestoda, Cyclophyllidea, Anoplocephalidae), an Intestinal Parasite of Arvicolidae Rodents

Spermiogenesis in Anoplocephaloides dentata begins with the formation of a differentiation zone delimited by a ring of arched membranes. This conical area shows 2 parallel centrioles with associated anterior reduced striated roots but without an intercentriolar body. Only 1 of the centrioles develops an axoneme that grows into a cytoplasmic extension. Two crestlike bodies appear when the nucleus initiates its migration along the spermatid body. We describe for the first time at the end of spermiogenesis the formation of an apical cone before the strangulation of the ring of arched membranes. The mature spermatozoon of A. dentata is filiform, tapered at both ends, and lacks mitochondria. Its anterior extremity has an apical cone measuring about 1,400 x 350 nm and 2 crestlike bodies. Cortical microtubules are spiralled at an angle of about 30 degrees to the spermatozoon axis. The axoneme, of the 9+1 pattern of Trepaxonemata (Polycladida, Seriata, "Typhloplanoida," "Dalyellioida," and Neodermata lacks a periaxonemal sheath and does not reach the extremities of the spermatozoon. Numerous granules of electron-dense material are observed in the posterior regions of each spermatozoon. Analysis of ultrastructural features found during spermiogenesis in A. dentata corroborates the presence of striated roots associated with the centrioles in cyclophyllidean species. Moreover, the presence of striated roots is described for the first time in type IV spermiogenesis.

Ultrastructure of spermiogenesis and the spermatozoon ofVampirolepis microstoma (Cestoda, Hymenolepididae), intestinal parasite ofRattus rattus

Spermiogenesis in Vampirolepis microstoma begins with the formation of a nuclear cone and a differentiation zone. This is delimited at the front by arched membranes, bordered by cortical microtubules, and contains two parallel centrioles linked together at their bases by electron-dense, amorphous material. The nuclear cone elongates, becomes filiform, and migrates into the spermatid body. Later, one of the centrioles gives rise to a flagellum that grows at the same pace as the cortical microtubules. Subsequently, 6 crested bodies form and the old spermatid separates from the residual cytoplasm. The mature V. microstoma spermatozoon is filiform and lacks mitochondria. Its anterior end exhibits six crested bodies 100 to 200 nm thick of unequal lengths. The axoneme is of the 9+"1" pattern. The cortical microtubules are spiralized and make an angle of about 20 to 30 degrees to the spermatozoon axis, except at their posterior extremity where they become parallel to this axis. The nucleus is an electron-dense cord coiled in a spiral around the axoneme. The cytoplasm is slightly dense but contains many electron-dense granules in regions III, IV, and V of the spermatozoon. The presence of centrioles linked together at their bases by electron-dense material has never, to our knowledge, been reported in a Platyhelminth. Likewise, a nuclear migration, right from the beginning to the end of spermiogenesis, has never been described in a cestode. In addition, we observe for the first time the existence of six crested bodies in a cestode from a Mammal.

Ultrastructure of the spermatozoon of the bank vole tapeworm, Paranoplocephala omphalodes (Cestoda, Cyclophyllidea, Anoplocephalidae).

The mature Paranoplocephala omphalodes spermatozoon is filiform, tapered at both ends and lacks mitochondria. Its anterior extremity exhibits an apical cone of electron-dense material measuring about 900 nm in length and 200 nm in width, and two crested-like bodies. The cortical microtubules follow a 25-35 degrees helicoidal path along their whole length, except at the posterior extremity where they become parallel to the spermatozoon axis. They are arranged in a single or two fields which may cover each other partially. The axoneme, of the 9 + "1" pattern of the Trepaxonemata, lacks a peri-axonemal sheath and does not reach the extremity of the spermatozoon. The nucleus is a compact and irregular cord coiled in a spiral around the axoneme. Moreover, we report for the first time a nucleus in the spermatozoon of a Cyclophyllidea species which reaches beyond the axonemal posterior extremity. The cytoplasm, depending on the level where the section is cut, is slightly electron dense or electron lucent and contains numerous small electron-dense granules in regions III-V. In the posterior spermatozoon extremity, granular material is replaced by a terminal and compact electron-dense material.

Ultrastructure of the spermatozoon of Dipylidium caninum (Cestoda, Cyclophyllidea, Dilepididae), an intestinal parasite of Canis familiaris.

We report for the first time the ultrastructure of the spermatozoon of a Dilepididae cestode. The mature spermatozoa of Dipylidium caninum is filiform and tapered at both ends and lacks mitochondria. The anterior extremity exhibits an apical cone of electron-dense material measuring about 600 nm in length and a single helicoidal crested-like body that is 150 nm thick. This single crested-like body is spiralized at an angle of about 40 degrees to the spermatozoon axis. The axoneme, showing the 9 + "l" pattern of the Platyhelminthes, lacks a periaxonemal sheath. The cortical microtubules constitute a continuous, submembranous, electron-dense material, and they are also twisted at an angle of about 40 degrees to the spermatozoon axis. Moreover, the nucleus is coiled in a helix around the axoneme, which is centrally located throughout its length. We demonstrate for the first time the presence of peripheral microtubules twisted to the spermatozoon axis up to the posterior extremity of the gamete.

Ultrastructure of the spermatozoon ofHymenolepis straminea(Cyclophyllidea, Hymenolepididae), intestinal parasite ofArvicanthis niloticus(Rodentia) in Senegal

Summary The mature H. straminea spermatozoon is filiform and lacks mitochondria. It exhibits an apical cone of electron-dense material and eight helicoidal crest-like bodies 50–100 nm in thickness. The cortical microtubules are spiralized and make an angle of about 30° to the spermatozoon axis. The axoneme, of the 9+“1” pattern of the Platyhelminthes, does not reach the extremities of the spermatozoon. The nucleus is a compact cord wound in a spiral around the axoneme. Depending on the level of section it appears annular or crescent-shaped. The cytoplasm exhibits many electron-dense granules in regions III, IV and V of the gamete. A nucleus with both annular and crescent-shaped sections has never been described in a species of the Hymenolepididae. In addition we report for the first time the existence of eight crest-like bodies of different length in the cestodes.

Comparative ultrastructure of the spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis (Cestoda, Anoplocephalidae, Inermicapsiferinae), intestinal parasites of rodents in Senegal

Spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis are filiform and tapered at both extremities. The anterior extremity exhibits an apical cone of electron-dense material and two helical ridges. The axoneme, of the 9 + "1" pattern, is surrounded over part of its length by a sheath of electron-dense material. At the posterior extremity the cytoplasm contains electron-dense material. In regions III and IV of the spermatozoa the cytoplasm is subdivided into compartments of electron-lucent material limited by irregularly spaced walls of electron-dense material. The sperm nucleus is a compact cord wound in a spiral around the axoneme. Cortical microtubules are helically arranged down the length of the spermatozoa except at the posterior extremity where they run parallel to the spermatozoon axis. In I. madagascariensis, cortical microtubules may not extend as far as the posterior extremity of the spermatozoa; the dense periaxonemal material exists in regions I to IV of the spermatozoon and the nucleus never coils more than once around the axoneme.

Ultrastructure of spermiogenesis and the spermatozoon of Aporina delafondi (Cyclophyllidea, anoplocephalidae), intestinal parasite of turtle doves in senegal

Spermiogenesis in Aporina delafondi begins with the formation of a differentiation zone bordered by cortical microtubules and containing from the beginning a portion of nucleus and two parallel centrioles. One of the centrioles aborts, the other gives rise to a flagellum. The cortical microtubules elongate and spiralize while the nucleus migrates along the axoneme and crest-like bodies form at the level of the differentiation zone. The old spennatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon lacks mitochondria, is filiform and tapered at both its extremities. Its anterior extremity is capped by an apical cone of electron-dense material and exhibits five crest-like bodies of unequal lengths on its periphery. Its cortical microtubules are regularly spiralized except at their posterior extremity where they become parallel to the spermatozoon axis. The cytoplasm is slightly dense in the anterior regions (I and II) and exhibits many protein granules and patches of electron-lucent material in the middle (III) and posterior zones (IV and V). The nucleus is an electron-dense cord coiled in a spiral around the middle region (III) of the axoneme. This is of the 9 + “1” pattern and ends before the posterior extremity of the gamete. Spermiogenesis in Aporina delafondi differs from that of the other Cyclophyllidea by the very early movement of the nucleus into the differentiation zone, the formation of a ring of arched membranes in the distal part of the differentiation zone, the appearance of crest-like bodies during migration of the nucleus and the formation of a cytoplasmic bud which contains the abortive centriole and develops to temporarily form a large lateral extension. The mature spermatozoon differs from that of the other Cyclophyllidea in the presence of lucent patches in its cytoplasm and of five helicoidal crest-like bodies. The systematic position of the genus Aporina is also debated.