Sperm Ultrastructure Research Articles

Sperm ultrastructure, morphometry, and abnormal morphology in American black bears ( Ursus americanus)

The objective of this study was to describe sperm ultrastructure, morphometry, and abnormal morphology in American black bears. Electroejaculation was successful in 53.8% (7/13) of the attempts, but urine contamination was common. Epididymal sperm samples were also obtained from five bears. Sperm had a paddle-like head shape and the ultrastructure was similar to that of most other mammals. The most striking particularity of black bear sperm ultrastructure was a tightening of the nucleus in the equatorial region. Although the differences were not significant in all bears, the overall decrease in sperm nucleus dimensions during transport from the caput epididymis to the cauda suggested increasing compaction of the nucleus during maturation. For ejaculated sperm, nucleus length, width, and base width were 4.9, 3.7, and 1.8 μm, respectively, whereas sperm head length, width, and base width were 6.6, 4.8, and 2.3 μm, and midpiece, tail (including midpiece), and total sperm lengths were 9.8, 68.8, and 75.3 μm. Evaluation of sperm cytoplasmic droplets in the epididymis revealed that proximal droplets start migrating toward a distal position in the caput epididymis and that the process was mostly completed by the time sperm reached the cauda epididymis. The proportion of morphologically normal sperm in the ejaculate was 35.6%; the most prevalent sperm defects were distal cytoplasmic droplets and bent/coiled tails. The morphology of abnormal sperm and the underlying ultrastructural defects were similar to that in other large domestic animals thus suggesting similar underlying pathogenesis of specific sperm defects and similar effects on fertility.

Spermatozoa of tapeworms (Platyhelminthes, Eucestoda): advances in ultrastructural and phylogenetic studies

New data on spermiogenesis and the ultrastructure of spermatozoa of 'true' tapeworms (Eucestoda) are summarized. Since 2001, more than 50 species belonging to most orders of the Eucestoda have been studied or reinvestigated, particularly members of the Caryophyllidea, Spathebothriidea, Diphyllobothriidea, Bothriocephalidea, Trypanorhyncha, Tetraphyllidea, Proteocephalidea, and Cyclophyllidea. A new classification of spermatozoa of eucestodes into seven basic types is proposed and a key to their identification is given. For the first time, a phylogenetic tree inferred from spermatological characters is provided. New information obtained in the last decade has made it possible to fill numerous gaps in the character data matrix, enabling us to carry out a more reliable analysis of the evolution of ultrastructural characters of sperm and spermiogenesis in eucestodes. The tree is broadly congruent with those based on morphological and molecular data, indicating that convergent evolution of sperm characters in cestodes may not be as common as in other invertebrate taxa. The main gaps in the current knowledge of spermatological characters are mapped and topics for future research are outlined, with special emphasis on those characters that might provide additional information about the evolution of tapeworms and their spermatozoa. Future studies should be focused on representatives of those major groups (families and orders) in which molecular data indicate paraphyly or polyphyly (e.g. 'Tetraphyllidea' and Trypanorhyncha) and on those that have a key phylogenetic position among eucestodes (e.g. Diphyllidea, 'Tetraphyllidea', Lecanicephalidea, Nippotaeniidea).

In vitro effects of tyre debris organic extract on the kinetic and morphologic traits of rabbit spermatozoa

The present study aims at evaluating the effects of the organic extract of tyre debris (TDOE) from tyre wear on the kinetic and morphologic features of rabbit spermatozoa. Rabbit sperm were incubated for 4 h with 0, 5, 10, 50 and 75 ?g/mL of TDOE. Sperm motility was evaluated by computer-assisted semen analysis. Phosphatidilcholine (PS) externalization (apoptosis) and plasma membrane breakage (necrosis) were assessed using the annexinV/propidium iodide assay. The sperm ultrastructure was observed by scanning (SEM) and transmission electron microscopy (TEM). A relevant decrease in the motility rate, PS externalization, and in plasma membrane breakage of spermatozoa were observed after incubation with TDOE at concentrations higher than 50 ?g/mL. The most frequent ultrastructural anomalies detected in the analysed specimens were: plasma and/or acrosomal membrane breakage, swollen and disorganized mitochondria, and altered axonemal patterns. Taken together, these results suggest that the organic extract of tyre debris can be toxic to rabbit spermatozoa ? affecting their movement and structural integrity ? when present in seminal plasma at a concentrations higher than 50 ?g/mL. Although rabbit sperm has been proven to be a suitable model for testing the in vitro effects of many chemical compounds, including TDOE, the obtained results must be considered preliminary and cannot be extrapolated yet to the in vivo outcomes because of scanty data. The results encourage, however, further research in this field.

Value of quantitative ultramorphological sperm analysis in infertile men

A specific cause of infertility cannot be identified in at least 25% of men referred to a specialized clinic. Diagnosis of infertile men is based mainly on standard semen analysis and the observation of sperm under light microscope. The aim of our study was to find the subcellular sperm characteristics that could explain infertility in a group of teratozoospermic infertile men. Morphological characteristics of sperm from non-teratozoospermic (control donors) and teratozoospermic infertile men were analyzed by transmission electron microscopy (TEM) and quantified. Our analysis showed that sperm cells from control donors presented a higher number of normal heads and tails than infertile men. Regarding subcellular characteristics of nucleus and tails, only the percentage of vacuolated nucleus, the absence of at least one pair of microtubules of the axoneme and the total distortion of the tail were statistically higher in infertile men than in control donors. There were no differences in the number of normal acrosomes between the groups. Although the ultrastructural sperm defects overlapped between control donors and infertile men, TEM permits the identification and differentiation of a larger amount of defects than light microscopy. Vacuolated nucleus and gross alterations of the tail are the major sperm defects that seem to have prognostic value in teratozoospermic men.

The Ultrastructure of Spermatozoa with a Note on the Formation of the Acrosomal Filament in the Lamprey, Lampetra japonica

The Ultrastructure of Spermatozoa with a Note on the Formation of the Acrosomal Filament in the Lamprey, Lampetra japonica

Ultrastructural study of the spermatozoon of Heterolebes maculosus (Digenea, Opistholebetidae), a parasite of the porcupinefish Diodon hystrix (Pisces, Teleostei)

This paper describes the ultrastructure of the mature spermatozoon of Heterolebes maculosus. It is the first study of this kind concerning the Opistholebetidae (Platyhelminthes, Digenea). The ultrastructural elements observed in the spermatozoon are: two axonemes with 9+“1” pattern of Trepaxonemata and their attachment zones, two mitochondria, a nucleus, cortical microtubules, external ornamentation of the plasma membrane and spine-like bodies. The number and the disposition of cortical microtubules, the organisation of 11 cortical microtubules disposed in semi-circle around the first mitochondrion in the external ornamentation region and the organisation of the posterior part of the spermatozoon are discussed. Three principal types of posterior part of digenean spermatozoa are proposed. The similarity between the spermatozoon of the Opistholebetidae H. maculosus and Opecoelidae enables us to confirm that these two families are closely related.

Light and transmission electron microscopic comparisons of sperms between petrochemical factory workers and public servants in a nonindustrialized area

In this study, we compared the semen characteristics on light microscopy and ultrastructural sperm morphology on transmission electron microscopy between workers in an industrialized area with petrochemical complexes and public servants in a nonindustrialized area. Occupational exposure to petrochemical compounds seems to decrease sperm motility and deteriorate the sperm ultrastructural arrangement, which may lead to this decrease in sperm motility.

Anatomy and ultrastructure of the male reproductive system in Pleioplana atomata (Platyhelminthes: Polycladida)

Abstract. The ultrastructure of the male reproductive system in the polyclad flatworm Pleioplana atomata is described. Numerous testes are scattered throughout the entire body but are heavily concentrated on the ventral side. All stages of differentiating sperm cells are present in all testes follicles. Intercellular bridges connect spermatocytes and spermatids derived from a single spermatogonium. In the distal part of spermatids, a zone of differentiation develops with a row of microtubules beneath the plasmalemma. Adjacent to these microtubules, an intercentriolar body is flanked by two basal bodies that give rise to two axonemes (each with a 9+“1” microtubular pattern) that face in opposite directions. The Golgi complex appears in the central portion of the spermatid and produces numerous small and large electron‐dense bodies. The small bodies surround the nucleus, whereas the large bodies cluster along with the mitochondria in the central part of the spermatid. Development of the spermatid leads to cell elongation and formation of a filiform, biflagellate mature spermatozoon with cortical microtubules all along the sperm shaft. The male canal system consists of paired vasa deferentia that separately enter a single seminal vesicle. A single prostatic canal connects the seminal vesicle to the prostatic vesicle. Ultrastructurally, the seminal vesicle and prostatic canal are very similar, and along with the prostatic vesicle and stylet pocket, are lined by a ciliated epithelium. The ultrastructure of the prostatic vesicle indicates that it probably produces a large volume of seminal fluid that, along with spermatozoa, is transferred to the mating partner through a stylet. Some of the findings, particularly on sperm ultrastructure, may provide characters useful for phylogenetic analysis.

Sperm ultrastructure of the hydrothermal vent octopod Vulcanoctopus hydrothermalis

Sperm ultrastructure of the deep-sea hydrothermal vent octopod Vulcanoctopus hydrothermalis has been carried out by transmission electron microscopy. Spermatozoa of this species have the shortest head observed so far in octopodids. The acrosome possesses a helix with six gyres. The rod-shaped nucleus is short and wide in relation with other octopodids. Noteworthy features along the nucleus are the regularly disposed dense bands of cytoplasm, which have not been observed before in octopodids. The nuclear fossa is very short and wavy. Mitochondrial sheath has 10 elongated mitochondria running parallel to the axoneme-coarse fibers complex. Sperm morphology of V. hydrothermalis resembles that of Enteroctopus dofleini, suggesting a close phylogenetic relationship.

RETRACTED: Sperm ultrastructure in two species of Panorpa and one Bittacus (Mecoptera)

The sperm ultrastructure of the scorpionflies Panorpa liui and P. longihypovalva in Panorpidae and the hangingfly Bittacus planus in Bittacidae were investigated using transmission electron microscopy. The common features of the spermatozoa shared by all the mecopterans examined include a bilayered acrosome with a central perforatorium, an elongated homogeneously condensed nucleus, and a long flagellum with a 9+2 axoneme pattern and two mitochondrial derivatives. The two species of Panorpa possess a fossa at the posterior end of the nucleus, and differ from B. planus by lacking both the globular units running laterally from the head to the flagellum and the Golgi complex-derived membrane present in the flagellum. P. liui has pear-shaped mitochondrial derivatives and two small accessory bodies, while P. longihypovalva has elliptical mitochondrial derivatives and only one accessory body. The marked differences of the sperm structure among the Panorpa examined further confirm the paraphyly of this genus.

Spermatological characters of the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890)

Spermiogenesis and the spermatozoon ultrastructure of the adult Didymobothrium rudolphii (Spathebothriidea) have been examined using transmission electron microscopy for the first time. The dense material is present in the apical region of the differentiation zone in the early stage of spermiogenesis, similarly as in other basal tapeworms examined to date. The orthogonal development of the two flagella is followed by a flagellar rotation and their proximodistal fusion with the median cytoplasmic process (MCP). The two pairs of electron-dense attachment zones in the MCP mark the lines where the proximodistal fusion of MCP with two axonemes takes place. D. rudolphii exhibits polymorphism of the intercentriolar body during spermiogenesis. The mature spermatozoon possesses the two axonemes of 9 + "1" trepaxonematan pattern, nucleus, cortical microtubules (CMs), and electron-dense granules. The anterior extremity of the gamete lacks a crested body and exhibits a centriole surrounded by a semiarc of electron-dense tubular structures. The two parallel rows of the CMs have been found in the proximal part of the two-axoneme region of the spermatozoon for the first time in the Eucestoda. The posterior extremity of the gamete exhibits pattern of the disorganized axoneme. The ultrastructural features of the sperm/spermiogenesis support a view about the close relationships of the Spathebothriidea and Diphyllobothriidea and the basal position of the Spathebothriidea within the Eucestoda.

Comparative sperm ultrastructure in Nemertea

Although the monophyly of Nemertea is strongly supported by unique morphological characters and results of molecular phylogenetic studies, their ingroup relationships are largely unresolved. To contribute solving this problem we studied sperm ultrastructure of 12 nemertean species that belong to different subtaxa representing the commonly recognized major monophyletic groups. The study yielded a set of 26 characters with an unexpected variation among species of the same genus (Tubulanus and Procephalothrix species), whereas other species varied in metric values or only one character state (Ramphogordius). In some species, the sperm nucleus has grooves (Zygonemertes virescens, Amphiporus imparispinosus) that may be twisted and give a spiral shape to the sperm head (Paranemertes peregrina, Emplectonema gracile). To make the characters from sperm ultrastructure accessible for further phylogenetic analyses, they were coded in a character matrix. Published data for eight species turned out to be sufficiently detailed to be included. Comparative evaluation of available information on the sperm ultrastructure suggests that subtaxa of Heteronemertea and Hoplonemertea are supported as monophyletic by sperm morphology. However, the data do not provide information on the existing contradictions regarding the internal relationships of "Palaeonemertea." Nevertheless, our study provides evidence that sperm ultrastructure yields numerous potentially informative characters that will be included in upcoming phylogenetic analyses.

Sperm ultrastructure of three Syllinae (Annelida, Phyllodocida) species with considerations on syllid phylogeny and Syllis vittata reproductive biology

Phylogeny of Syllidae is under debate due to new studies based on molecular and morphological data. The noticeable taxonomic diversity of syllids (about 700 listed species) is also mirrored in the array of reproductive strategies as well as in sperm morphology, counting a display of forms already supposed to reflect phylogenetic relationships between the species. The sperm ultrastructure of Syllis gerlachi, S. prolifera and S. vittata is herein presented and compared to the Syllinae species studied previously. Moreover, the egg structure and the gamete allocation within stolons of S. vittata are particularly investigated. Both male germinal cells at different level of maturation and oocytes were found in the same individual of S. vittata, suggesting simultaneous hermaphroditism. The ultrastructural analysis revealed that the observed spermatozoa belong to the ect-aquasperm type resembling those of the similar studied species (Syllis sp., S. pigmentata and S. krohni). Differences in the acrosome structure and nucleus shape are in accordance with a recent phylogenetic reconstruction and suggest a trend in the evolution of spermatozoa in Syllinae toward the development of the apical part. However, further molecular and ultrastructural analyses are needed to support this hypothesis. This is the first record of simultaneous hermaphroditism within Syllinae.

Ultrastructure of spermiogenesis and mature spermatozoon of Anonchotaenia globata (von Linstow, 1879) (Cestoda, Cyclophyllidea, Paruterinidae)

AbstractYoneva, A., Georgieva, K., Mizinska, Y., Nikolov, P. N., Georgiev, B. B. and Stoitsova, S. R. 2010. Ultrastructure of spermiogenesis and mature spermatozoon of Anonchotaenia globata (von Linstow, 1879) (Cestoda, Cyclophyllidea, Paruterinidae). — Acta Zoologica (Stockholm) 91: 184–192The ultrastructure of spermiogenesis and of the spermatozoon of a species of the family Paruterinidae is described for the first time. The spermiogenesis of Anonchotaenia globata starts with the formation of a differentiation zone with two centrioles associated with thin striated roots. One of the centrioles gives rise to a free flagellum followed by a slight flagellar rotation and a proximodistal fusion of the flagellum with the cytoplasmic protrusion. This pattern corresponds to Type III spermiogenesis in cestodes. The spermatozoon consists of five distinct regions. The anterior extremity possesses an apical cone and a single helically coiled crested body. The cortical microtubules are spirally arranged. The axoneme is surrounded by a periaxonemal sheath and a thin layer of cytoplasm filled with electron‐dense granules in Regions I–V. The periaxonemal sheath is connected with the peripheral microtubules by transverse intracytoplasmic walls in Regions III and IV. The nucleus is spirally coiled around the axoneme. Anonchotaenia globata differs from Dilepididae (where paruterinids have previously been classified) in the type of spermiogenesis, the lack of glycogen inclusions and the presence of intracytoplasmic walls. The pattern of spermiogenesis is similar to that in Metadilepididae and Taeniidae, which are considered phylogenetically close to Paruterinidae.

Spermiogenesis and spermatozoon ultrastructure of the davaineid cestode Raillietina micracantha (Fuhrmann, 1909)

AbstractMiquel, J., Torres, J., Foronda, P. and Feliu, C. 2010. Spermiogenesis and spermatozoon ultrastructure of the davaineid cestode Raillietina micracantha. — Acta Zoologica (Stockholm) 91: 212–221The spermiogenesis and the ultrastructural organization of the spermatozoon of the davaineid cestode Raillietina micracantha are described by means of transmission electron microscopy. Spermiogenesis begins with the formation of a zone of differentiation containing two centrioles. One of the centrioles develops a free flagellum that later fuses with a cytoplasmic extension. The nucleus migrates along the spermatid body after the proximodistal fusion of the flagellum and the cytoplasmic extension. During advanced stages of spermiogenesis a periaxonemal sheath and intracytoplasmic walls appear in the spermatids. Spermiogenesis finishes with the appearance of two helicoidal crested bodies at the base of spermatids and, finally, the narrowing of the ring of arched membranes detaches the fully formed spermatozoon. The mature spermatozoon of R. micracantha is a long and filiform cell, tapered at both ends, which lacks mitochondria. It exhibits two crested bodies of different lengths, one axoneme of the 9 + ‘1’ pattern of trepaxonematan Platyhelminthes, twisted cortical microtubules, a periaxonemal sheath, intracytoplasmic walls, granules of glycogen and a spiralled nucleus. The anterior extremity of the spermatozoon is characterized by the presence of an electron‐dense apical cone and two spiralled crested bodies while the posterior extremity of the male gamete exhibits only the axoneme and an electron‐dense posterior tip.

610 Method of differential breast tumour diagnostics

The present study intended for displaying the effect of different freeze-drying media and temperature of storage on the ultrastructure and DNA of freeze-dried buffalo bull spermatozoa. The semen samples undergone freeze-drying were raw semen and frozen-thawed semen extended in Tris-Fructose-Egg yolk-Glycerol.Semen samples were processed in two portions: First portion was cryopreserved with Tris-Fructose-Egg yolk-Glycerol extender to be freeze-dried with the different media used in this study. Second portion was freeze-dried immediately with the different media used in this study. Semen samples were centrifuged in a percoll gradient (45–90%) for 20 min at 700 × g to remove seminal plasma. Subsequently, sperms were washed twice in Tyrode's albumen lactate pyruvate (TALP) to remove percoll remains, and allocated into the four freeze-drying media (media 1, 2, 3 and 4) respectively. The media tested were: medium 1 (EGTA solution), medium 2 (EDTA solution), medium 3 (TCM199 with Hanks salts and 10% FCS) and medium 4 (TCM199 with Hanks salts and 10% FCS and trehalose). For all the media used, samples were diluted, placed in tubes of 1.5 ml and kept at room temperature for 30 min. Then sperm cell suspensions were cooled in liquid nitrogen vapor (approximately −80 °C for 1 h), by keeping the tubes at a distance of 5 cm from liquid nitrogen surface before plunged into it. Frozen samples were immediately inserted into the freeze-drying machine, previously stabilized at (−40 °C) and 350 × 10−3 Mbar pressure. After 12–16 h of freeze-drying, the tubes containing the samples were covered with aluminum foil and stored for 3 months at different temperatures; 4 °C, −20 °C and −80 °C. Freeze-dried sperm samples were re-hydrated by adding 100 μL of milli-Q water at room temperature. To evaluate sperm ultrastructure, transmission electron microscopy was done. For detection of DNA fragmentation, commet assay was performed.Electron microscopy showed that the sperm cell component most affected by freeze-drying was the plasma membrane, which was destroyed in all media either in raw or frozen thawed sperm. Microtubules organization was also disorganized in the majority of the sperm from freeze-drying medium 2 and 3, diverging from freeze-drying media 1 and 4, in which microtubules were intact. Conversely, the acrosome and mitochondria were well protected in all media. However, the storage temperature has no effect. The freeze-drying medium with EDTA solution exhibited and the lowest percent of DNA damage (9.3) while the freeze-drying medium (TCM with trehalose) exhibited the highest percent of DNA damage (13.6) at temperature of storage (4 °C). In contrast, the freeze-drying medium with EGTA solution exhibited the lowest percent of DNA damage (15.3) while the freeze-drying medium (TCM with trehalose) exhibited the highest percent of DNA damage (18) at temperature of storage (−20 °C). On the other hand, the freeze-drying medium with EDTA solution exhibited the lowest percent of DNA damage (11.3) while the freeze-drying medium (TCM with trehalose) exhibited the highest percent of DNA damage (20) at temperature of storage (−80 °C). Consequently, the freeze-drying medium (TCM without trehalose) exhibited the lowest percent of DNA damage (6.5) while the freeze-drying medium with EDTA solution exhibited the highest percent of DNA damage (13.9) at temperature of storage (4 °C). On the contrary, the freeze-drying medium with EGTA solution exhibited the lowest percent of DNA damage (13.2) while the freeze-drying medium (TCM without trehalose) exhibited the highest percent of DNA damage (20.8) at temperature of storage (−20 °C). Conversely, the freeze-drying medium with EDTA solution exhibited the lowest percent of DNA damage (6) while the freeze-drying medium (TCM with trehalose) exhibited the highest percent of DNA damage (12) at temperature of storage (−80 °C).From the present study, we demonstrated that the freeze-drying medium containing EGTA and EDTA solution were more efficient in avoiding damage to components of buffalo bull sperm, especially the nuclei. Therefore, the medium used for freeze-drying process directly affected sperm nuclear integrity. Also, the storage temperature of freeze-dried sperm affects sperm nuclear integrity.

Ultrastructural studies on euspermatozoa and paraspermatozoa in Mantispidae (Insecta, Neuroptera)

Previous studies have demonstrated the presence of sperm dimorphism in the Mantispidae Perlamantispa perla. We extended the study on several other mantidflies. In all the examined species the occurrence of euspermatozoa (typical) and paraspermatozoa (atypical) was established. The euspermatozoa are characterized by the presence of a cylindrical nucleus surrounded by an envelope that fans out laterally into two thin wings of different length. The acrosome seems to be missing. The nucleus is surrounded by extracellular material. The flagellum is provided with a 9 + 9 + 2 axonemal pattern; the accessory tubules contain 16 protofilaments and the intertubular material has the distribution typical of the taxon. Two elongated accessory bodies flank partially the axoneme and connect this structure with the mitochondrial derivatives. The flagellar axoneme of paraspermatozoa consists of an axoneme and two giant mitochondrial derivatives filled with large globular units. The axoneme exhibits a 9 + 9 + 2 pattern, in which the central 9 + 2 units have a normal structure, in that the microtubular doublets are provided with both dynein arms and radial links. On the contrary, the nine accessory microtubules have a large diameter and their tubular wall consists of 40 protofilaments. This comparative study provided evidences about the uniformity of sperm ultrastructure in Mantispidae. The function of non-fertilizing giant sperm in mantidflies is discussed.

Acrosomal ultrastructure of stallion spermatozoa cryopreserved with ethylene glycol using two packaging systems.

The present experiments aimed to examine the substitution of glycerol (G) by ethylene glycol (E) as a cryoprotective agent for stallion spermatozoa. Two different ethylene glycol concentrations (5% and 10%) and also the association of glycerol (2%) and ethylene glycol (3%) (E/G) were studied (Experiment 1). In Experiment 2, two packing systems (0.5 x 4.0 ml) were evaluated using both cryoprotectors. In both experiments, the sperm membrane integrity after freezing was evaluated using transmission electron microscopy. The mean post-thaw motility was 34.25, 36.5, 29.25 and 34.75% for G5%, E5%, E10% and E/G, respectively. It was observed that the percentage of motile spermatozoa was significantly smaller (P<0.05) when semen was processed with E10%. A decrease in the acrosome integrity was observed in frozen thawed spermatozoa from all treated groups. It was observed that 28.0, 22.5, 25.5 and 22.5% of the sperm cells had a normal acrosome following freezing with G5%, E5%, E10% and E/G, respectively. Undulation of the outer acrosomal membrane, acrosomal swelling and loss of acrosomal content density and homogeneity were the most evident ultrastructural alterations observed. In Experiment 2, the post-thaw motility was higher (P<0.05) for sperm frozen in 0.5 ml straws than in 4.0 ml straws, regardless of the cryoprotector used. The ultrastructural evaluation showed 26.7 and 16.0% of intact acrosomes for sperm frozen in 0.5 ml and 4.0 ml straws, respectively. We concluded that ethylene glycol has similar cryoprotective properties to glycerol and that utilisation of 0.5 ml straws improved the ability of horse sperm cells to withstand damage after the cryopreservation process.

Spermiogenesis and spermatozoon of the tapeworm Parabothriocephalus gracilis (Bothriocephalidea): Ultrastructural and cytochemical studies

AbstractSpermiogenesis and spermatozoon ultrastructure of the tapeworm Parabothriocephalus gracilis were described using transmission electron microscopy (TEM). Spermiogenesis is characterized by the formation of a zone of differentiation with two centrioles associated with striated rootlets, and an intercentriolar body between them. The two flagella undergo a rotation of 90° until they become parallel to the median cytoplasmic extension with which they fuse. Electron-dense material is present in the apical region of the zone of differentiation in the early stages of spermiogenesis. This electron-dense material is characteristic for the orders Bothriocephalidea and Diphyllobothriidea. The mature spermatozoon contains two axonemes of the 9 + ‘1’ trepaxonematan pattern, nucleus, parallel cortical microtubules and electron-dense granules of glycogen. The anterior extremity of the spermatozoon exhibits a single helical electron-dense crested body 130 nm thick. One of the most interesting features is the presence of a ring of cortical microtubules surrounding the axoneme. This character has been reported only for species of the order Bothriocephalidea and may be unique in this cestode group.

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The reviewer has raised interesting points, in addition to those discussed in our article about the possible effects that smoking might have on semen quality. Retrospective Assessment of Potential Negative Synergistic Effects of Varicocele and Tobacco Use on Ultrastructural Sperm MorphologyUrologyVol. 74Issue 4PreviewTo investigate, in a retrospective study, whether smoking cigarettes increases the effect of varicocele on sperm morphology. Full-Text PDF Editorial CommentUrologyVol. 74Issue 4PreviewThis report highlights the challenges clinical researchers face in designing studies whose primary objective is to answer even simple, straight-forward questions. In this case, whether smoking cigarettes further reduces the fertility potential in men with varicoceles. Full-Text PDF