Apical Cone Research Articles

Assessment of dental students’ knowledge and performance of master gutta-percha cone selection and fitting during root canal treatment: a pilot study

BackgroundMisconceptions should be detected early in dental students’ training to improve their clinical performance. Accordingly, this study aimed to assess undergraduate dental students’ knowledge and performance of master gutta-percha (GP) cone selection and fitting during clinical endodontic courses at the College of Dentistry, King Saud University.MethodsNinety-nine undergraduate dental students completed an online survey about their knowledge of master GP cone selection. Forty-five of these students were observed by faculty members in clinical endodontic courses while they fitted master GP cones during root canal treatments. The observers recorded the details of each student’s cone-fitting techniques. The data were analysed using t-tests, one-way analysis of variance, and chi-square tests (p < 0.05). Inter- and intra-observer reliability were tested using Fliess’ Kappa.Results SurveyAll participants had good knowledge of over-extended cone management, while 80.8% knew how to properly manage a short cone. The proper flaring assessment method was selected by 86.9% of the female and 34.2% of the male students, and this difference was statistically significant (p = 0.0001).ObservationThe students labelled the working length on the master GP cone with an indentation in 64.4% of the cases and by bending the cone 35.6% of the time. Of all students, 84.4% encountered an apical stop, and this rate correlated significantly with the length of the cone on the master apical cone radiograph (p = 0.001). Improper shaping of the canal was the most common cause of ill-fitting cones (83.3%), while 16.7% of the students chose the wrong cone size. The final obturation length was adequate in 80% of the cases; 57.8% of the students were helped by instructors.ConclusionsMost students had the basic knowledge required to solve problems related to the selection of master GP cones. However, in the clinical setting, more than half of the students required the assistance of an instructor to adjust their cone’s fit. The presence of an apical stop had the most significant effect on the length of the fitted master GP cone on radiography. The most common cause of ill-fitting master cones was improper shaping of the canal.

ЛАХАРЫ НА О. АТЛАСОВА В СЕНТЯБРЕ-ОКТЯБРЕ 2022 Г. (КУРИЛЬСКИЕ ОСТРОВА)

The article provides information about nival-volcanogenic, possibly glacial-volcanogenic, mudflows (lahars) on three streams on the south side of Atlasov Island (Kuril Islands, Russia). The island is an active stratovolcano Alaid, 2339 m asl high. The effusive-explosive eruption of the Alaid volcano began on September 10, 2022 and continues to the present day. Strombolian activity of the apical cone and lava outflow is observed. Lava filled the summit caldera by September 27. The lava flow then crossed the southern part of the caldera crest and began to descend down the erosional depression at the tops of the catchments of three unnamed streams. Photography and satellite images showed the presence of mudflow transformation of stream beds and slopes, and mudflows fan at the mouths of the streams. Analysis of meteorological and volcanological data showed that the formation of lahars was caused by rapid melting of snow/ice under the influence of lava flow and it occurred between September 29 and October 2.

Efficacy of flukicides on Fasciola gigantica, a food-borne zoonotic helminth affecting livestock in Bangladesh.

Fasciola gigantica, the causative agent of tropical fasciolosis, is a food-borne zoonotic trematode that affects around 80% livestock of Bangladesh. Triclabendazole (TCBZ), nitroxynil (NTON) and oxyclozanide (OCZN) are frequently used against fascioliasis; however, the current status of potency of these flukicides was unknown. In this study, in vitro efficacy of TCBZ, NTON and OCZN at various concentrations on F. gigantica has been evaluated by relative motility (RM), morphological distortions of apical cone through an inverted microscope, architectural and ultra-structural changes through histopathological and scanning electron microscopy (SEM). It is observed that TCBZ, NTON and OCZN at higher concentrations significantly (P < 0.05) reduced RM of the flukes compared to untreated control. NTON at 150 μg mL−1 was the most potent to reduce the motility within 4 h whereas TCBZ and OCZN were much delayed. Histopathological changes showed swollen, extensive cracking, numerous vacuoles and splitting of the tegument surrounding the spines; spine dislodged from its socket in treated flukes compared to untreated worms. Histopathological changes were more conspicuous at higher doses of TCBZ, NTON and OCZN. SEM has shown the disruption of the apical cone, apart from swelling of the tegument on the ventral surface corrugation and disruption of the ventral apical cone. All these changes indicate that NTON is the most potent in killing flukes in vitro among the tested flukicides and suggest the presence of TCBZ-resistant fluke populations in Bangladesh. It is imperative to explore the in vivo effects of these flukicides and subsequently their molecular mechanisms.

Keratoconus Features on Corneal Higher-Order Aberration Ablation Maps: Proof-of-Concept of a New Diagnostic Modality.

PurposeTo assess the potential application of corneal higher-order aberration (HOA) excimer ablation map imaging in identifying reproducible keratoconus (KC) features and to explore if newly derived map metrics correlate to Pentacam KC indices.MethodsCase series of 12 eyes with KC ≥ grade 2. Topolyzer Vario corneal imaging with its resultant HOA ablation map islands were analyzed for their centroid, distance from center, angular position, orientation, sphericity, diameter, area, and maximal ablation depth. Correlations to Pentacam indices were studied.ResultsAll eyes showed recurrent features with an arrangement of two elliptical paracentral ablation islands, one deep inferotemporal and one shallow superonasal, in direct mirror-like opposition to each other. These were always accompanied by superior peripheral ablation crescents. The two paracentral islands had highly reproducible distance from center (1.2 ± 0.1 mm and 1.3 ± 0. 2 mm) and angular positions (246.8 ± 15.9° and 76.7 ± 7.7°), with greater variation in ablation depth (68.3 ± 33.2 µm and 17.6 ± 12.1 µm). Distance from center of the peripheral superior crescents was highly reproducible (3.3 ± 0.1 mm), with a larger range of depth (74.5 ± 37.2 µm). The deep paracentral inferotemporal island “hot spot” was coincident with the topographical apical cone. Strong correlations were found between the depth of the inferotemporal island and Pentacam indices of posterior radius curvature (PRC: R = −0.74) and Belin/Ambrosio enhanced ectasia total deviation (BAD-D: R = 0.71).ConclusionThe corneal HOA ablation map revealed a recurring, distinct, easily recognizable pattern in KC eyes. There was a strong correlation between the depth of novel HOA ablation map metrics and validated Pentacam KC indices. Novel information can be extracted from the corneal HOA ablation map giving it the potential to be a new modality to diagnose and grade KC.

Freezing tolerance of bread winter wheat and its relation with morphological features

In recent years there have been significant changes in weather conditions during wheat growth and development. The aim of the study was to establish the relationship between the level of freezing tolerance of bread winter wheat varieties and their morphological features. The study was conducted during 2016–2019 at the V.M. Remeslo Myronivka Institute of Wheat. 19 bread winter wheat varieties bred at Myronivka were studied. Freezing tolerance of plants was determined according to DSTU 4749:2007 which based on freezing wheat plants in chambers at -18 ºC and -20 ºC with pre-hardening in the open field. The high-frost-tolerant wheat variety Myronivska 808 was used as standard of freezing tolerance. Statistical data processing was performed according to Fisher’s test. Morphological condition of plants was estimated in autumn after vegetation dormancy onset and in spring after its restoration according to the F.M. Kuperman method. The research years were characterized by contrasting weather conditions. It was found that the most bread winter wheat varieties bred at Myronivka have high and medium level of freezing tolerance. Over the years of the research, the elongation of apical cone in the standard variety Myronivska 808 varied from 0.01 to 0.42 mm. In the varieties studied, the elongation of apical cone ranged within 0–0.10 mm (2016– 17), 0.35–0.68 (2017–18) and 0.03–0.32 mm (2018–19). According to the assessment of freezing tolerance, there have been identified valuable bread winter wheat varieties with percent of viable plants over the years of the research exceeding standard variety Myronivska 808 or being at the same level. The varieties MIP Kniazhna, Trudivnytsia myronivska, Lehenda Myronivska, Estafeta myronivska, Vezha myronivska, MIP Dniprianka, MIP Assol were high frost tolerant ones. On average, over the years of the research the varieties MIP Kniazhna, Trudivnytsia myronivska, Lehenda Myronivska, Estafeta myronivska, Vezha myronivska, MIP Dniprianka, and MIP Assol had elongation of apical cone at the level of the Myronivska 808 variety. The variation of the strength and direction of connections between the level of frost resistance and morphological indicators (plant height, length of the growth cone) determined at the time of termination and restoration of winter wheat vegetation was established. Key words: winter wheat, varieties, freezing tolerance, growth, development, apical cone.

Tibetyrus gen. nov., a new myrmecophilous Tyrini from Xizang, China(Coleoptera: Staphylinidae: Pselaphinae).

Tibetyrus formicarius Yin Lin, gen. et sp. nov., a new myrmecophilous genus and species of the pselaphine tribe Tyrini, is described from southeastern Xizang, China. Three adults were collected in nests of a Formica ant species (Hymenoptera: Formicidae) at an altitude of 3,485 m. Tibetyrus is similar to Megatyrus Hlaváč Nomura in sharing the basally pedunculate maxillary palpi that lack an apical cone on the fourth palpomeres. Nevertheless, it can be readily separated from the latter and all other genera of the tribe by its unique suite of morphological features as well as a highly recognizable habitus.

Influence of photoperiod on morphogenetic processes in near-isogenic lines in PPD genes of soft wheat

Aim. Investigation of the effects of contrast photoperiodic conditions and the state of the Ppd genes (dominant or recessive) on growth and morphogenetic reactions in NILs of soft winter wheat Myronivska 808 and Mercia cultivars. Methods. Experiments were carried out in field and vegetation chamber conditions. NILs were cultivated in contrast photoperiodic conditions: control group plants – in the conditions of a long photoperiod of 16 hours (LD), experimental group plants – in a short photoperiod – 9 hours (SD). The stages of organogenesis, the height of apical growth cones, the number of tillers and biomass of the above-ground part of plants were determined. Results. In our studies, we found that all NILs of both cultivars respond to a photoperiod reduction as typical long-day plants, namely: they have a two-stage of organogenesis delay in development, growth processes are inhibited (growth of the apical cone, formation of tillering shoots and accumulation of plant biomass). It was shown that NILs with the genotypes Ppd-A1a and Ppd-D1a are characterized by accelerated development due to inhibition of growth processes. Conclusions. The genes responsible for controlling the development and photoperiodic sensitivity of soft wheat plants also determine the pace of development, growth and morphogenetic reactions of common wheat plants as in LD photoperiod conditions (16 hours), as well as in SD photoperiod conditions (9 hours).&#x0D; Keywords: Triticum aestivum L., Ppd genes, photoperiod, stages of organogenesis, shoot apex.

Radiographic Quality of Root Canal Obturation Performed By Fifth Year Students of Hamadan Dental School.

The aim of this study was to assess the radiographic technical quality of root canal therapy performed by fifth year students of Dental School of Hamadan University of Medical Sciences from 2015 to 2016. Four hundred and seventy records of root canal therapies were evaluated. Records with graphies taken as initial, master apical file (MAF), master apical cone (MAC) and final radiographs were included in the study and records of patient younger than 16 years and older than 68 years were excluded from further investigations. Lastly, 432 teeth were selected. Obturation length, canal tapering, quality and density of filling material were the variables investigated in the present study. Two independent investigators examined the radiographies using a magnifying lens (×2) and x-ray viewer. Data were analyzed using chi-square test. The technical quality of root filling performed by undergraduate dental students was classified as acceptable in 10.4% of cases. Moreover, 70.8% of teeth had adequate filling, 17.1% were underfilled and 12% were overfilled. The three groups were significantly different in terms of working length and taper quality. One hundred ninety four (44.9%) records had adequate taper and 109 (25%) records had adequate density. There was a significant association between teeth location and the length of obturation so that the probability of a successful treatment was higher in maxillary teeth. Furthermore, the rate of a proper length of obturation was higher among incisors than that of premolars and molars. The technical quality of root canal therapy performed by dental students in Hamadan University of medical sciences is not as acceptable as it should be. One of the most important factors in this regard is a high student/professor ratio.

A correlation analysis of cone characteristics and central keratometric readings for the different stages of keratoconus

Background:Knowledge of the cone characteristics for the different stages of keratoconus may potentially assist practitioners in diagnosing and managing keratoconic patients.Aim:This study aims to determine if any correlation exists between the central keratometric readings and the cone characteristics for the different stages of keratoconus.Setting:A university eye clinic.Materials and Methods:In this retrospective study, a saturated sample of 190 eyes from 106 cases of previously diagnosed keratoconic patient files was analyzed. The stage of keratoconus and cone characteristics, namely, cone location, cone decentration, topographical patterns, and morphology were analyzed using an Oculus 3M corneal topographer.Results:Analysis revealed a correlation between cone decentration and stage of keratoconus (P = 0.007). The association was found to exist when central K-readings were between 45D and 52D and with an apical cone decentration of 3–4 mm. No correlations were obtained for the stage of keratoconus and the cone location; topography and morphology.Conclusion:It can be concluded that cone apices are not central in all stages. Practitioners should consider the peripheral cornea when diagnosing and managing keratoconic patients. No correlation between stage, morphology or topography was respectively revealed.

СОРТОВЫЕ ОСОБЕННОСТИ РАЗВИТИЯ ГИСТОЛОГИЧЕСКИХ ЗОН КОНУСА НАРАСТАНИЯ ПОБЕГА ЯРОВОЙ ПШЕНИЦЫ

СОРТОВЫЕ ОСОБЕННОСТИ РАЗВИТИЯ ГИСТОЛОГИЧЕСКИХ ЗОН КОНУСА НАРАСТАНИЯ ПОБЕГА ЯРОВОЙ ПШЕНИЦЫ

Echinococcus multilocularis Leuckart, 1863 (Taeniidae): new data on sperm ultrastructure.

The present study establishes the ultrastructural organisation of the mature spermatozoon of Echinococcus multilocularis, which is essential for future research on the location of specific proteins involved in the sperm development in this species and also in Echinococcus granulosus. Thus, the ultrastructural characteristics of the sperm cell are described by means of transmission electron microscopy. The spermatozoon of E. multilocularis is a filiform cell, which is tapered at both extremities and lacks mitochondria. It exhibits all the characteristics of type VII spermatozoon of tapeworms, namely a single axoneme, crested bodies, spiralled cortical microtubules and nucleus, a periaxonemal sheath and intracytoplasmic walls. Other characteristics observed in the male gamete are the presence of a >900-nm long apical cone in its anterior extremity and only the axoneme in its posterior extremity. The ultrastructural characters of the spermatozoon of E. multilocularis are compared with those of other cestodes studied to date, with particular emphasis on representatives of the genus Taenia. The most interesting finding concerns the presence of two helical crested bodies in E. multilocularis while in the studied species of Taenia, there is only one crested body. Future ultrastructural studies of other species of the genus Echinococcus would be of particular interest in order to confirm whether or not the presence of two crested bodies is a characteristic of this genus.

Apical Gutta-percha cone adaptation and degree of tug-back sensation after canal preparation

Aims: The aim of this study was to investigate the degree of tug-back after canal preparation with respect to the Gutta-percha-occupied area (GPOA). Materials and Methods: Roots of twenty premolar teeth were prepared till size 35/0.04, then GP cones of same size and taper were adapted to root canals and the degree of tug-back sensation was scored as loose, slight, adequate, and strong. Root canals were filled with GP and AH26 sealer, and then sectioned horizontally 1 mm from the apical end at three levels. GPOA and its sum from the three levels sum of GPOA (sGPOA%) were calculated using digital stereomicroscope. Statistical Analysis: At each sectioned level, GPOA% was compared with the score of tug-back sensation using one-way ANOVA at a 5% significance level. Multiple pairwise comparisons were performed using Tukey test. Results: Tug-back sensation was present in all canals, described as slight, adequate, and strong in 4, 8, and 8 canals, respectively. Among the tug-back scores, quantitative analyses of GPOA% showed significant differences at 2- and 3-mm levels. The strong tug-back with sGPOA of 76.5 ± 11.1% was significantly higher than that of slight tug-back. Conclusions: Under the conditions of this study, the tug-back scoring system can be applied to determine the amount of GP adaptation inside the root canal. Strong tug-back sensation showed the highest GP adaptation although at least one-fifth of the apical canal region was left unfilled.

Lamellar changes in the keratoconic cornea.

The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning. Five surgically removed keratoconic corneal buttons and four, non-keratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled. A seamless digital montage was printed at 5000× magnification. Lamellae were counted in the anterior-posterior orientation, along a linear line, using established criteria for identification of individual lamellae. The stromal thickness estimated as a 95% confidence interval for the mean, CI (0.95), in the keratoconic corneas was 372± 62μm, while in the normal cornea, it was 446±89μm. All keratoconic corneas showed ultrastructural evidence of lamellar splitting and a loss of interweaving anterior lamellae. In the keratoconic corneas, the median total linear stromal lamellar absolute count tangential to the corneal surface was 362, (25th percentile; 75th percentile)=(355; 365) lamellae and in the normal cornea, 246, (25th percentile; 75th percentile)=(239; 251). The linear lamellar density in the keratoconic corneas was estimated as CI (0.95) 117±22 and 86±19 lamellae per 100μm in the anterior and posterior portion of the stroma, respectively. In normal cornea, the linear lamellar density was estimated as CI (0.95) 51±8 and 80±20 lamellae per 100μm. The mean difference of linear lamellar count between the anterior and the posterior portion of the cornea was estimated as CI (0.95) 31±23 for keratoconic corneas and -29±28 for the normal corneas. The current morphometric analysis of ultrastructural changes suggests that ectasia and thinning in keratoconus is associated with lamellar splitting into multiple bundles of collagen fibrils and loss of anterior lamellae. These structural changes, possibly in addition to lateral shifting of lamellae due to the pressure gradient over the cornea, are a potential explanation to the central loss of mass.

Spermatological characteristics of the genus Taenia inferred from the ultrastructural study on Taenia hydatigena.

The present study attempts to establish the sperm ultrastructure baseline for Taenia hydatigena, which is essential for the future research on the location of specific proteins involved in spermatogenesis in this species. Thus, the ultrastructural organisation of the mature spermatozoon is described by means of transmission electron microscopy. Live tapeworms were obtained from an experimentally infected dog in the Department of Pathology and Public Health of the Agronomic and Veterinary Institute Hassan II of Rabat (Morocco). The spermatozoon of T. hydatigena is a filiform cell, which is tapered at both extremities and lacks mitochondria. It exhibits all the characteristics of type VII spermatozoon of tapeworms, namely a single axoneme, a crested body, spiralled cortical microtubules and nucleus, a periaxonemal sheath and intracytoplasmic walls. Other interesting characteristics are the presence of a 2000 nm long apical cone in its anterior extremity and only the axoneme in its posterior extremity. The ultrastructural characters of the spermatozoon of T. hydatigena are compared with those of other cestodes studied to date, with particular emphasis on representatives of the genus Taenia.

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.

The antimicrobial effect of apical box versus apical cone preparation using iodine potassium iodide as root canal dressing: A pilot study

Purpose.The purpose was to study the reduction of intra-canal microflora in premolars with apical periodontitis instrumented with either apical box or apical cone preparation and to provide measurements of intervention effects to allow proper power calculation in future clinical trials. Methods. Twenty-four patients were centrally randomized to apical box preparation (size #60) or cone preparation (apical size #25). The groups were comparable regarding the presence of primary caries and type of coronal restoration. In the course of canal preparation each tooth was irrigated with 2.5% NaOCl (12 ml). Lastly, the canals were filled with 17% EDTA (2 × 30 s) and 5% iodine potassium iodide (IKI) for 10 min. The canals were sampled for micro-organisms on four occasions: before instrumentation, after instrumentation, after application of IKI dressing and at the beginning of the second appointment 1 week later. Between the treatment sessions, the root canals were sealed with IRM cement. In the laboratory, culture techniques were used to measure microbial growth, which was classified as: none, very sparse, sparse, moderate, heavy or very heavy. Results. Initially, microbes were recovered in 88% of the teeth. Growth was classified as none in 35% of the teeth after instrumentation and in 50% after the application of IKI. Irrespective of the time of sampling, no significant difference in microbial growth reduction was observed between the two types of apical preparation. Based on the 1-week post-sampling, a power calculation revealed that over 900 patients are needed to show a difference of 9% between the two protocols tested. Conclusions. Future trials should be conducted using stringent protocols and as multi-centre trials for reaching the required information size.

Effects of Mirazid® and myrrh volatile oil on adult Fasciola gigantica under laboratory conditions

ObjectiveTo evaluate the effects of Mirazid® and myrrh volatile oil on adult Fasciola gigantica (F. gigantica) under laboratory conditions. MethodsThe effects of oleoresin extract of myrrh (Mirazid®) and myrrh volatile oil on the surface morphology of adult F. gigantica following treatment in vitro had been determined by scanning electron microscopy. The results were compared with those observed in the fluke tegument following incubation in triclabendazole sulphoxide (TCBZ-SO), active form, (Fasinex®, Ciba-Geigy). ResultsObservations of the efficacy of Mirazid® oleoresin extract and myrrh volatile oil indicated that both products showed dose-dependent anthelmintic efficacy. The anterior half of the fluke was consistently more severely affected than the posterior half. The surface changes induced by Mirazid® oleoresin extract were less severe than those observed after exposure to either myrrh volatile oil or TCBZ-SO. Flukes showed swelling after these treatments, but its level and blebbing were much greater with myrrh volatile oil; in which patches of tegumental sloughing were observed in the apical cone and the posterior mid-body region of flukes. This was not observed after treatment with Mirazid® oleoresin extract. ConclusionsThe comparatively more disruption, observed in myrrh volatile oil exposed specimens, compared to that exposed to Mirazid® oleoresin extract might suggest that the anthelmintic activity of Mirazid® oleo resin extract was attributed to its content of volatile oil. So, increasing the concentration of myrrh volatile oil in Mirazid® might possibly help to developing its anthelmintic activity.

Spermiogenesis and spermatozoon ultrastructure of the paruterinid cestode Notopentorchis sp. (Cyclophyllidea)

Ultrastructural characters of the spermiogenesis and mature spermatozoon of Notopentorchis sp. (Cestoda, Cyclophyllidea, Paruterinidae), a parasite from Apus affinis (Aves, Apodiformes, Apodidae) from Gabon, are described by means of transmission electron microscopy. Cytochemical analysis for detection of glycogen was applied. Vestigial striated roots associated with the two centrioles are present in the zone of differentiation. The spermiogenesis is characterized by an external growth of free flagellum followed by a proximodistal fusion of the latter with cytoplasmic protrusion, thus, corresponding to the cestode spermiogenesis of the type III pattern described by Bâ and Marchand (Mem. Mus. Natl. Hist. Nat. 166:87-95, 1995). In the final stage of spermiogenesis, a single crested body appears at the base of the forming spermatozoon. The mature spermatozoon of Notopentorchis sp. is filiform and tapering at both extremities. It consists of five regions differing in their ultrastructural characteristics. The anterior extremity of the mature spermatozoon is characterized by the presence of an apical cone and a single crested body. The cytoplasm contains one axoneme of 9 + "1" type of the trepaxonematan Platyhelminthes, a periaxonemal sheath, a layer of twisted cortical microtubules, transverse intracytoplasmic walls, and granules of glycogen. The nucleus is coiled in spiral around the axoneme. The posterior extremity of the spermatozoon is characterized by the presence of electron-dense material. This structural organization corresponds to the morphology of cestode spermatozoon of type VII as defined by Levron et al. (Biol Rev 85: 523-543, 2010). The comparison of the results with those of the two previous studies on paruterinids suggests that several characters of the spermiogenesis and the mature spermatozoon are invariable, i.e. the type III spermiogenesis and the presence of vestigial striated roots, a single crested body, a periaxonemal sheath, and intracytoplasmic walls. The main differences of the sperm cells among members of this family are the lack of dense granules (as in Triaenorhina rectangula) and the presence of electron-dense material in the posterior extremity of the spermatozoon (as in Notopentorchis sp.).

Ultrastructural study of spermiogenesis and the spermatozoon of the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009, a parasite of the catfish Clarias gariepinus (Burchell, 1822) (Siluriformes, Clariidae)

Spermiogenesis in the proteocephalidean cestode Barsonella lafoni de Chambrier et al., 2009 shows typical characteristics of the type I spermiogenesis. These include the formation of distal cytoplasmic protrusions forming the differentiation zones, lined by cortical microtubules and containing two centrioles. An electron-dense material is present in the apical region of the differentiation zone during the early stages of spermiogenesis. Each centriole is associated to a striated rootlet, being separated by an intercentriolar body. Two free and unequal flagella originate from the centrioles and develop on the lateral sides of the differentiation zone. A median cytoplasmic process is formed between the flagella. Later these flagella rotate, become parallel to the median cytoplasmic process and finally fuse proximodistally with the latter. It is interesting to note that both flagellar growth and rotation are asynchronous. Later, the nucleus enlarges and penetrates into the spermatid body. Finally, the ring of arching membranes is strangled and the young spermatozoon is detached from the residual cytoplasm.The mature spermatozoon presents two axonemes of the 9+‘1’ trepaxonematan pattern, crested body, parallel nucleus and cortical microtubules, and glycogen granules. Thus, it corresponds to the type II spermatozoon, described in almost all Proteocephalidea. The anterior extremity of the gamete is characterized by the presence of an apical cone surrounded by the lateral projections of the crested body. An arc formed by some thick and parallel cortical microtubules appears at the level of the centriole. They surround the centriole and later the first axoneme. This arc of electron-dense microtubules disorganizes when the second axoneme appears, and then two parallel rows of thin cortical microtubules are observed. The posterior extremity of the male gamete exhibits some cortical microtubules. This type of posterior extremity has never been described in proteocephalidean cestodes. The ultrastructural features of the spermatozoon/spermiogenesis of the Proteocephalidea species are analyzed and compared.

Sperm ultrastructure of Helicometra epinepheli (Platyhelminthes, Digenea, Opecoelidae), parasite of Epinephelus fasciatus (Pisces, Teleostei).

This paper describes the ultrastructure of the mature spermatozoon of the digenean Helicometra epinepheli. The ultrastructural elements observed are: two axonemes with a 9+"1" pattern of Trepaxonemata, four attachment zones, a nucleus, two mitochondria, external ornamentation of the plasma membrane, spine-like bodies and cortical microtubules. A particularity of this spermatozoon is the presence of an apical cone. However, the spermatozoon presents the general pattern of the Opecoelidae and thus differs from Helicometra fasciata (which appears as an exception in this family) by several ultrastructural features: the presence of external ornamentation and spine-like bodies and the arrangement of cortical microtubules around the first mitochondrion in the region of the ornamentation. Each ultrastructural feature is discussed and compared with the literature to highlight characters which could be useful for phylogeny.