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The scolex ultrastructure was studied in Grillotia (Christianella) carvajalregorum (Cestoda: Trypanorhyncha) using histochemistry and transmission electron microscopy. We show for the first time the presence of scolex glands arranged in two longitudinal acini at the pars vaginalis parenchyma. These glands, along with those scattered in bothrial parenchyma, produce potentially adhesive glycoprotein secretions that are discharged via ducts to the bothrial grooves and apex. A particular type of sensory receptor was found around frontal gland pores, with a possible function in regulating their secretion activity. The internal structure of microtriches varies according to their morphotype and distribution on the scolex, this study providing the first description of the ultrastructure of serrate lanceolate spinitriches. The projections that form serrate margins are an extension of the medulla, differing from similar projections of other spinitriches. The large caps observed in serrate lanceolate spinitriches may reflect their specialization in attachment to and abrasion of intestinal mucosa, while the short caps and large bases of acicular filitriches may reflect their involvement in nutrient absorption. We also describe the rhyncheal apparatus ultrastructure, showing a similar basic structure of tentacular walls than that of other trypanorhynchs. Some differences among species in the number of fibrous layers, composition of the apical cytoplasm and presence of microvilli-like projections were discussed. Finally, our study describes in detail the internal ultrastructure of hollow hooks, evidencing the presence of cytoplasm, mitochondria and fibrils. The location of these fibrils may increase the area of contact surface of hooks on tentacles, possibly allowing for a higher tensile strength than that of solid hooks. We consider that gland location and shape, composition of tentacular wall layers, and hook internal structure may serve as useful characters for the taxonomy and phylogeny of Trypanorhyncha. RESEARCH HIGHLIGHTS: This is the first description of scolex internal ultrastructure in Grillotia carvajalregorum, showing the presence of glands arranged in two longitudinal acini at the pars vaginalis parenchyma, with potentially adhesive functions. The internal ultrastructure of serrate lanceolate spinitriches and acicular filitriches may reflect their specialization in attachment to the host intestinal mucosa and their involvement in nutrient absorption, respectively. Internally, hollow hooks have cytoplasm with mitochondria and fibrils, which are more widely distributed than in solid hooks, possibly increasing their tensile strength., (© 2020 Wiley Periodicals LLC.)

The efficacy of anthelmintic treatments against populations of endoparasites infecting livestock throughout the world is decreasing. To mitigate this, the use of fecal egg counts is recommended to determine both the necessity, and to ensure the appropriate choice, of anthelmintic treatment. Traditionally, and in order to facilitate easier identification and/or enumeration, samples are analysed after separating eggs from other fecal particulates by exposing them to a solution with a density higher than that of the eggs, but lower than the remaining fecal contents. While many parasite egg flotation protocols exist, little is known about the characteristics of these eggs with respect to their movement through a flotation solution. In this study, we have demonstrated a novel method for the observation and quantification of microscopic (65-100 µm) objects as they experience unassisted flotation. This also represents, to our knowledge for the first time, that the flotation of parasite eggs has been observed and their movement characteristics quantified as they float through solution. Particle tracking and video analysis software were utilised to automatically detect and track the movement of individual eggs as they floated. Three 30 s videos and one 2 min video of each egg type were analysed. If the first 30 s of video were discounted, the differences in mean flotation speed among all videos was statistically significant between egg types (P = 0.0004). Strongyle type eggs (n = 201) moved the fastest with a mean 51.08 µm/s (95% confidence interval: 47.54-54.62). This was followed by Parascaris spp. (n = 131) and Anoplocephala perfoliata eggs (n = 322), with mean speeds of 44.43 µm/s (95% confidence interval: 39.47-49.4) and 31.11 µm/s (95% confidence interval: 29.6-32.61), respectively. This method for evaluating the mean speed of passive flotation may represent a first step towards further optimizing fecal egg flotation and be of interest to parasitologists and veterinary practitioners., (Copyright © 2019 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.)

Monozoic caryophyllidean cestodes, intestinal parasites of cyprinid fishes, represent a group of tapeworms with an unclear evolutionary history. As spermatology may provide phylogenetically important data, the spermiogenesis and ultrastructure of the mature spermatozoon have been investigated using an integrative approach combining transmission electron microscopy, cytochemistry and electron tomography in Khawia rossittensis (Szidat, 1937). The process of spermatid formation is accompanied by the presence of ultrastructural characters not described in traditional models of spermiogenesis, e.g., apical electron-dense material, the two striated roots situated unusually opposite each other, branching of typical striated roots, an intercentriolar body comprising five electron-dense and four electron-lucent layers, rotation of both free flagella and flagellar buds to the median cytoplasmic process at 90°, and a complete proximodistal fusion. The synchronous rotation of both flagellar buds and growing free flagella is an evolutionarily linked pattern favouring the hypothesis that the Caryophyllidea are not ancestral but are secondarily derived from polyzoic forms. Electron tomography analysis has revealed a unique feature of two helicoidal tubular structures in the central electron-dense core of the axoneme of mature spermatozoon. These data provide new insights into the architecture of the 9 + '1' axoneme, which is shared by male gametes of all trepaxonematan Platyhelminthes.

We present the first reported case from the United States of human infection with the intestinal cestode Raillietina, a parasite primarily of rodents and poultry. As the differential diagnosis between the morphologically similar Dipylidium caninum was challenging, we discuss the biology, epidemiology, and clinical management of this rare parasite., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

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.

The recently erected cestode order Diphyllobothriidea is unique among all tapeworm orders in that its species infect all major groups of tetrapods, including man. In the present paper, the vitellogenesis of representatives of all three currently recognized families of this order was evaluated, based on ultrastructural (transmission electron microscopy) and cytochemical (detection of glycogen) observations. Vitelline follicles of all taxa studied, i.e. Cephalochlamys namaquensis from clawed frogs (Xenopus), Duthiersia expansa from monitors (Varanus) and Schistocephalus solidus that matures in fish-eating birds, contain vitelline cells at various stages of development and interstitial cells. Developing vitellocytes are characterized by the presence of mitochondria, granular endoplasmic reticulum and Golgi complexes involved in the synthesis of shell globules and formation of shell globule clusters. Mature vitellocytes contain lipids and glycogen in different proportions. The most significant differences among the three diphyllobothriidean families were found in the presence or absence of lamellar bodies. Variations of vitelline clusters morphology and types of lipid droplets are described and discussed in relation to the presumed evolutionary history of diphyllobothriideans, which belong to the most basal cestode groups., (Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.)

One of the best examples of rapid displacement of native species by an invader is the eradication of native Artemia salina and A. parthenogenetica in the Mediterranean by the introduced American A. franciscana. Previous studies based on sampling from limited time periods suggest that the success of the American species as a competitor may be due partly to different parasite burden, since native Artemia spp. have high cestode infection rates regulating their density. The aim of this study is to test the hypothesis that the helminth infection in A. franciscana in its invasive range is low throughout its annual life cycle. Samples of A. franciscana were collected every second month from La Tapa saltern (Andalusia) during one year. Five helminth species were recorded: cestodes Flamingolepis liguloides, F. flamingo, Gynandrotaenia stammeri (all flamingo parasites), Eurycestus avoceti (a shorebird parasite) and larval spirurids of the Acuariinae (the first record of nematodes in Artemia). The overall infection rate was low, with total prevalence 5.9% and prevalence of individual parasite species between 0.2 and 3.2%. The mean abundance of helminths was 0.005-0.155 (av. 0.068), 5-13 times lower than in native congeners. Waterbird counts indicate that the low infection rates cannot be explained by lack of definitive hosts. The results are consistent with the hypothesis that helminths have no regulating effect on the invasive brine shrimp in the Mediterranean. The replacement of the native populations by the invader can be partially explained by a competition mediated by parasites/predators through a differential impact on host fitness.

Current copro-diagnostic tests for Anoplocephala perfoliata show high variation in their sensitivity and given the morphological similarity of Anoplocephala spp. eggs, this could be related to the presence of Anoplocephala magna alone or co-existing with A. perfoliata. In the present study, coprology was significantly more sensitive (p<0.01) at detecting A. magna than A. perfoliata. This difference was independent of the parasite burden and was greater when testing was limited to horses with mature or gravid tapeworms. A. magna infection was strongly linked to young horses (≤ 2 years). The eggs of A. magna are smaller. Using 15 and 70 μm cut-offs for oncosphere diameter and the major shell bisector length, respectively, the eggs of A. perfoliata were identified with 100% sensitivity, 97% specificity and 98% sensitivity, 84% specificity. The use of these two morphometric variables would therefore be useful for the copro-identification of A. perfoliata in countries where both species coexist., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The therapeutic benefits of medicinal plants in terms of anthelmintic properties are known since time immemorial in India, particularly among natives of the Northeast India. However, only sporadic and scarce reports on scientific validation of these plants are available. The present study was conducted on the cestode Raillietina echinobothrida, to establish whether the anthelmintic activity of Potentilla fulgens, Alpinia nigra and Millettia pachycarpa was mediated by apoptosis or not. Light microscopic observation following MTT assay revealed the highest percentage of inhibition of viability among the worms by methanol extract of M. pachycarpa (89.33%), followed by A. nigra (65%) and P. fulgens (37%). Ultrastructural observations revealed swelling of mitochondria, disruption of mitochondrial membrane, vacuolization of mitochondria, appearance of apoptotic bodies in the cytoplasm, disintegration of nuclear membrane and nucleolus were very common throughout the tegument. DAPI stained specimens showed typical morphology of apoptosis, like nuclear condensation and fragmentation in the extracts treated parasites. A decrease in mitochondrial membrane potential was also recorded in the treated groups. Confirmatory TUNEL assay and DNA fragmentation assay of the extracts treated parasites also confirmed the apoptotic nature of cell death and is concluded to be responsible for paralysis and death of the parasite., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The vitellarium of the invasive caryophyllidean tapeworm Khawia sinensis Hsü, 1935 from carp Cyprinus carpio L. was examined by means of transmission electron microscopy and cytochemical staining for glycogen with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP). A vitellarium consists of numerous follicles of irregular size that are interconnected by a net of vitelline ducts. Vitelline follicles are composed of vitelline cells at various stages of development that are interconnected by interstitial tissue. Vitelline follicles are surrounded by a cytoplasmic sheath associated with an intercellular matrix. Extensive development of the granular endoplasmic reticulum and Golgi complexes are both involved in the production of shell globules/shell globule clusters and characterise cytodifferentiation of vitellocytes. Nuclear and nucleolar transformation lead to the formation and storage of intranuclear glycogen, a feature specific for the Caryophyllidea. Newly observed within the mature vitellocytes of Khawia sp. is the presence of lamellar bodies and a few lipid droplets. These cytoplasmic inclusions first occur in the mature cells within the follicles and persist in the vitelline cells within vitelloducts and intrauterine eggs. Two types of lamellar bodies are detected: regular lamellar-structured body and irregular lamellar-structured body. None of the lamellar bodies are membrane bound. Results of the present study indicate that the formation of lamellar bodies may be closely related to the endoplasmic reticulum or shell globule clusters. Some of the shell globule clusters are transformed into lamellar body clusters. Ultrastructural features of vitellocytes in K. sinensis are compared with those of other monopleuroid, polypleuroid, and strobilated cestodes.

This is the first TEM examination of vitellogenesis in the cestode Aporhynchus menezesi, a parasite of the velvet belly lanternshark Etmopterus spinax and a member of a little-studied trypanorhynch family, the Aporhynchidae. The synthetic activity of vitellocytes plays two important functions in the developmental biology of cestodes: (1) their shell-globules serve in eggshell formation; and (2) their accumulated reserves of glycogen and lipids represent a food source for the developing embryo. In A. menezesi, vitelline follicles consist of cells at various stages of development, from peripheral, immature cells of the gonial type to mature cells towards the centre of the follicle. These stages are: (I) immature; (II) early differentiation; (III) advanced maturation; and (IV) mature. Gradual changes involved in this process occur within each stage. Vitellogenesis involves: (1) an increase in cell volume; (2) the development of a smooth endoplasmic reticulum and an accelerated formation and accumulation of both unsaturated and saturated lipid droplets, along with their continuous enlargement and fusion; (3) the formation of individual β-glycogen particles and their accumulation in the form of glycogen islands scattered among lipid droplets in the cytoplasm of maturing and mature vitellocytes; (4) the rapid accumulation of large, moderately saturated lipid droplets accompanied by dense accumulations of β-glycogen along with proteinaceous shell-globules or shell-globule clusters in the peripheral layer during the advanced stage of maturation; (5) the development of cisternae of granular endoplasmic reticulum that produce dense, proteinaceous shell-globules; (6) the development of Golgi complexes engaged in the packaging of this material; and (7) the progressive and continuous enlargement of shell-globules into very large clusters in the peripheral layer during the advanced stage of maturation. Vitellogenesis in A. menezesi, only to some extent, resembles that previously described for four other trypanorhynchs. It differs in: (i) the reversed order of secretory activities in the differentiating vitellocytes, namely the accumulation of large lipid droplets accompanied by glycogenesis or β-glycogen formation during early differentiation (stage II), i.e. before the secretory activity, which is predominantly protein synthesis for shell-globule formation (stage III); (ii) the very heavy accumulation of large lipid droplets during the final stage of cytodifferentiation (stage IV); and (iii) the small number of β-glycogen particles present in mature vitellocytes. Ultracytochemical staining with PA-TCH-SP for glycogen proved positive for a small number of β-glycogen particles in differentiating and mature vitellocytes. Hypotheses, concerning the interrelationships of patterns of vitellogenesis, possible modes of egg formation, embryonic development and life-cycles, are commented upon., (Copyright © 2012 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.)

Chromosomes of the invasive tapeworm Khawia sinensis (Caryophyllidea), the specific parasite of common carp, were analyzed by means of conventional Giemsa staining and using fluorescent DAPI and YOYO-1 dyes, silver staining, and fluorescent in situ hybridization (FISH) with 18S rDNA probe. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n = 3m + 5t, TCL = 42.54 μm). Constitutive heterochromatin was located at pericentromeric regions of all pairs, except for the largest metacentric pair (no. 1), which possessed no DAPI-positive band. FISH with rDNA probe revealed that both homologues of chromosome pair no. 6 carry a cluster of ribosomal arrays, which were located interstitially close to the centromere. Present results are compared with previous cytogenetic data on Khawia spp., and comments are made on the karyotypes with respect to their phylogenetic links.

Spermiogenesis of the monozoic cestode Caryophyllaeus laticeps (Pallas, 1781) (Caryophyllidea: Caryophyllaeidae), a parasite of Abramis brama (Pisces: Cyprinidae), has been investigated by means of transmission electron microscopy and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for glycogen. The process of spermatozoon formation corresponds in the basic pattern to that of Khawia armeniaca as described by Bruňanská and Poddubnaya (Parasitol Res 99:449-454, 2006). The dense material at the early stages of spermiogenesis, an intercentriolar body, the formation of a free flagellum and flagellar bud, the penetration of the nucleus into the spermatid body when the fusion of the free flagellum with the median cytoplasmic process has started, and a complete proximodistal fusion have been determined. In contrast to previous data on the caryophyllidean type spermiogenesis, the latter more recent observations show the presence and the rotation of a free flagellum and a flagellar bud. This pattern indicates clearly a derived stage of spermiogenesis in the Caryophyllidea, when the second shorter flagellum is greatly reduced comparing with that in the Spathebothriidea, Diphyllobothriidea, or Bothriocephalidea, thus forming a flagellar bud. The flagellar bud occurs in all stages of spermiogenesis and represents an evolved character in the Caryophyllidea. The mature spermatozoon of C. laticeps consists of one axoneme of the 9 + "1" trepaxonematan structure, parallel cortical microtubules, and a nucleus. Cell components are situated in a moderately electrondense cytoplasm, containing glycogen in the principal regions (II, III, and IV) of the spermatozoon. A crested body is absent. Similarities and differences between spermatozoa of caryophyllideans as well as other Eucestoda are discussed.

Vitellogenesis in the parthenogenetic caryophyllidean tapeworm Atractolytocestus huronensis Anthony, 1958, parasitizing the carp Cyprinus carpio L., has been examined using light (LM) and transmission electron microscopy and cytochemical staining with periodic acid-thiosemicarbazide-silver proteinate for glycogen. It was found that formation of vitellocytes shares the same basic patterns in lower tapeworms with parthenogenetic and normal reproduction. Each vitelline follicle of A. huronensis consists of vitellocytes at various stages of development and an interstitial tissue. Projections of the interstitial tissue surround each vitellocyte and extend as a cytoplasmic sheath on the follicular periphery. In contrary to other Eucestoda, interstitial tissue of A. huronensis includes numerous electron-dense vesicles of various sizes. Maturing and mature vitellocytes contain vitelline material in the form of single small shell globules, which may gradually fuse and give rise to the large shell globule clusters. Shell globule clusters are of two types in A. huronensis. Additional vitelline material is represented by single "lamellar" granules and glycogen in the cytoplasm of mature vitellocytes. The ultrastructural features of vitellogenesis and/or vitellocyte in A. huronensis are compared with that in other caryophyllideans and/or Neodermata.

It is still unclear whether flatworms have specialized glial cells. At present there are no special methods available for the identification of glial cells in flatworms. The aim of this research was to carry out detailed investigations of the CNS in two species ofcestodes, and to get an idea whether these cells may fit into the concept of glia. Three types of glial cells have been found in Grillotia erinaceus: (1) fibroblast-like cells in the cerebral ganglion (CG); (2) glial cells in bulbar nerves with filaments and laminar cytoplasm; (3) a 3rd type of cells forms multilayer envelopes in the main cords (MC); also they make contacts with the excretory epithelium. To demonstrate the existence of glial cells, an immunocytochemical and ultrastructural investigation of Ligula intestinalis was undertaken. Intensive S100b-like immunoreaction (IR) was found in the GG and in the MC. IR-varicosities were mostly located asymmetrically on the MC, and no IR was found in neuropiles. Small glial cells were found on the surface of the MC; they have oval nuclei and dense cytoplasm with slim processes going around the neuropile and enclosing neurons. Long junctions are seen between cell processes but with neurons they usually possess juxtaposition contacts. Glial cells lack vesicles or synapse-like structures. Intensive S100b-like-IR has been shown in the CNS of cestodes for the first time. Results from ultrastructural research support the immunocytochemical date.

The ultrastructure of the infective oncosphere of the cestode Mosgovoyia ctenoides (Anoplocephalidae) is described. The surface of the infective oncosphere is covered by a thin cytoplasmic layer of tegument connected by a narrow cytoplasmic process with the binucleate subtegumental cell, situated deeper in the body. Below the basal matrix of the cytoplasmic layer of the tegument are situated wide bands of the peripheral, somatic musculature responsible for body movements. The 3 pairs of hooks and their muscles form a complex hook muscle system, responsible for coordinated hook action. Five major types of cells have been distinguished: (1) a binucleate subtegumental cell, (2) a binucleate penetration gland, (3) 2 nerve cells, (4) numerous somatic cells, and (5) about 6 germinative cells. The approximate number of cells is 24 (26 nuclei, including 2 syncytial structures). The results of this study, when compared with other published reports from other cestode taxa, support previous hypotheses that the progressive reduction of oncosphere cells is an adaptive feature in cestode evolution.

The crude root-peel extract of Flemingia vestita, genistein and praziquantel were tested against some selected glycolytic enzymes--hexokinase (HK), phosphofructokinase (PFK), phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and malic enzyme (ME)--of the fowl tape worm, Raillietina echinobothrida. Following exposure to the various treatments, the activities of HK, PFK, PEPCK and LDH increased by 33-39%, 41-125%, 44-49% and 55-67%, respectively, and that of PK decreased by 14-26% in the parasite at the time of paralysis. The MDH and ME activities of the tissue homogenate were also found to be higher by 22-43% and 28-59%, respectively, in the treatments. However, whereas the activity of both cytosolic and mitochondrial MDH increased by 33-58% and 43-73%, respectively, the cytosolic ME activity showed an increase of 33-39%, and there was no significant enhancement in the mitochondrial ME activity. Histochemically, the enhancement in the activities of HK, LDH and MDH was clearly discernible. The enhanced glycolytic activity seems to be a function of anthelmintic stress caused by the phytochemicals., (Copyright 2004 Springer-Verlag)

The tegument of the mature proglottids of M. ctenoides was examined by means of TEM. The tegument of this species consists of two layers: (1) the external cytoplasm, and (2) the tegumental perikarya situated in the cortical parenchyma. The tegument surface is covered by typical microtriches. The anucleated external layer of cytoplasm is rich in vesicles of different shape and electron-density, but it lacks mitochondria. Large pore canals penetrate the external cytoplasmic layer. This layer is separated from the perikarya by a basal lamina, being connected with the tegument cell bodies by cytoplasmic bridges. The granular cytoplasm of perikarya contains typical cell organelles such as mitochondria, GER, Golgi complexes, free rybosomes, numerous vesicles and lipid droplets inclusions. The large nuclei of the perikarya with prominent nucleoli frequently contain large intranuclear, highly osmiophilic lipid droplets.

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.

The cellular composition of parenchyma was studied in the ontogenesis of Triaenophorus nodulosus and it was shown that the specialized parenchymal cells was absent. The extracellular matrix fibrils were synthesized successively by the tegumental cytons and muscle cells. The coracidium basal matrix consisted of electron-light and electron-dense layers, and the reticular layer appeared at the procercoid stage. Reserve nutrients were accumulated by the musculocutaneous sac elements at the procercoid stage and, later, by the glandular and tegumental cells. It has been proposed that the parenchyma as an independent histological unit is absent, while the parenchymal organization is based on all specialized cellular elements that do not lose their typical features.

In the scolex-neck region of the adult Proteocephalus macrocephalus two types of eccrine gland cells are present. The first type of gland cells, localized in the frontal part of the scolex only, contains large, more or less round electron lucid granules. The second type of unicellular glands produces large electron dense granules. These electron dense granular gland cells are localized primarily in the neck region, only few are present in the scolex apex. The secretion of both types of gland cells is concentrated in the ducts opening to the exterior. The ducts are fixed to the plasmalemma of the tegument by septate junctions. The function of both types of gland cells is discussed.

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.

Background: Contributors regularly submit specimens to our institute and suggest a diagnosis of cestode infection, but the structures in question are actually lipomembranous changes that produce lipid pseudomembranes. This required a reproducible method to distinguish lipid pseudomembranes from body walls of cestodes., Methods: We describe and compare the morphologic and histochemical features of specimens from 20 patients. Nine specimens represented lipid pseudomembranes, and 11 represented one of the following five entities: cysticercus, coenurus, sparganum, hydatid of Echinococcus granulosus, or metastatic solid-bodied cyclophyllidean (possibly cysticercoid) larval cestodes. Specimens were stained with hematoxylin-eosin, Gomori's methenamine-silver, and 72-hour oil red O. Nine patients with cestodes, and all with lipid pseudomembranes, presented with subcutaneous lesions., Results: In all specimens, oil red O provided marked contrast between lipid pseudomembranes and surrounding tissue, but focal or minimal contrast between larval cestodes and surrounding tissue. Unlike hematoxylin-eosin, Gomori's methenamine-silver stain produced distinctly different staining patterns in larval cestodes and lipid pseudomembranes., Conclusions: This technique readily permitted a simple, reproducible, and accurate distinction between lipid pseudomembranes and cestode body walls and distinguished between body walls of different cestodes.

The ultrastructure and histochemistry of the scolex of a Polypocephalus species is described. This cestode is distinguishable from all known Polypocephalus spp. in that it has approximately 400 tentacles and inhabits the musculature of the blue swimmer crab, Portunus pelagicus. The metacestode has a large scolex, divided into an anterior par apicalis, and a posterior pars basalis. An elongate cercomer lies posteriorly to the scolex. The pars basalis lacks accessory suckers. The tegument of this region is armed with numerous spinous microtiches. The pars apicalis consists of approximately 400 unarmed tentacles, a large cavity ( = scolex cavity) containing some glandular tissue, and lying posteriorly to this cavity, a large gland ( = scolex gland). The tegument of the tentacles and pars apicalis is typically syncytial, and contains abundant electron-opaque secretory vesicles. These vesicles are produced by glandular tissue of the scolex gland and scolex cavity. Histochemistry revealed the presence of proteins and neutral mucosubstances in tentacles, scolex gland and scolex cavity, suggesting the presence of glycoproteins. It is argued that the secretion produced by the tentacles has an adhesive role. When applied to the large interface between the tentacles and the mucosa of the hosts, this secretion may provide the adult parasite with a strong holdfast to prevent dislodgement.

A simple technique using modified Mallory stain in the transferral of Gyrodactylus specimens from ammonium picrate-glycerin to a permanent mountant is described. Hamuli, their connecting bars and the penis sclerites are well defined by the technique as are muscles and tendons, cell nuclei, tegument and gland cells. As well as being useful in the study of general anatomy, the technique enhances the observation of the taxonomically important ventral and dorsal bars. In order to show this, improved illustrations of the dorsal and ventral bars of G. turnbulli are given along with explicit demonstrations of differences in morphology of the ventral bars of G. bullatarudis and G. rasini-two easily confused species.

Immunoblotting, SDS-PAGE and western blotting procedures were used to demonstrate cross-reactivity of a polyclonal anti-carp IgM antibody with components of roach serum. The polyclonal antibody labelled 2 major bands in both immune and normal roach sera corresponding to molecular masses of approximately 90 and 65 kDa. One of these bands (65 kDa) was considered to be heavy chain of fish immunoglobulin whilst the identity of the other remains uncertain. This cross-reaction has been exploited in immunofluorescence and immunogold labelling studies to localize fish host molecules on the tegumental membrane of Ligula intestinalis freshly removed from roach fry. Immunogold studies revealed a low level of host molecules to be associated mainly with the microthrix spines of the tegument with less gold labelling being observed on the microthrix shafts.

In subsequent co-infections of Sobolevicanthus gracilis and Fimbriaria czaplinskii an elimination of the majority of specimens of the first species by the next one has been found at the early stage of development. This did not depend on the fact, which species was the first. In concurrent control co-infections of larvae of both species mentioned above developed simultaneously and correctly. It seems to testify the existence of interspecific competition expressed by a peculiar sensibility of larvae at their early stages of development (3rd to 5th day post infection). The longer the larvae of the first species develop the fewer of them become eliminated by the next one.

The karyotypes of Vampirolepis nana, Hymenolepis diminuta and Vampirolepis erinacei (Cestoda: Cyclophyllidea) have been described. The number of chromosomes in the diploid cell of the studied taxa was 2n = 12. The absolute and the relative lengths of the chromosomes of V. nana and H. diminuta were measured. The chromosomes had similar metric values. In the karyotypes of V. nana and H. diminuta there were ten one-arm chromosomes and one two-arm chromosome (the third in length in the karyotype of V. nana and the first in length in the karyotype of H. diminuta). The chromosomes in the karyotype of V. erinacei had one arm which was proved by the terminal localization of the constitutive heterochromatin. The examined species differed in the morphology of some chromosomes in the karyotypes.

Two Proteocephalus species, P. neglectus La Rue, 1911 and P. exiguus La Rue, 1911, parasites of salmonid and coregonid fishes, were compared morphologically, biometrically, and electrophoretically. The study revealed that the two taxa cannot be differentiated by the morphological criteria used. No fixed allelic difference was found. In all, 12 of 13 enzymes detected by isoelectric focusing exhibited virtually identical isoenzyme profiles in both species. Only in the glutamate oxaloacatate transaminase enzyme locus was a difference observed. The negligible differences in zymograms and morphology, including similar biometric variability of the taxa studied, suggest that the species could be conspecific.

A method for isolating an enriched preparation of tegumental brush border from the tapeworm, Hymenolepis diminuta, is described. Combining incubation of whole tapeworms in Krebs-Ringer/tris-maleate solution containing a hemolytic saponin, low shear-force agitation, and differential centrifugation, a pellet is obtained at 2,500 g which contains a significant concentration of surface brush border. The content of brush border in this fraction is identified by the presence of numerous microvilli, increased specific radioactivity after surface tagging with 3H-Concanavalin A, and relatively little mitochondrial contamination (succinic dehydrogenase). Based on morphological criteria, fractions sedimenting with greater force contain dense vesicles and mitochondria from the outer portion of the tegument.

Caulobothrium longicolle (Linton, 1890) and Phyllobothrium gracile (Weld, 1855) (Cestoda: Tetraphyllidea, Phyllobothriidae) have the same embryonic development with the following characteristic data: --a small number of vitelline cells (2 or 3) pass with the zygote in the ootype;--a non operculate thin egg-shell;--the entire and equal zyhote cleavage following by unequal divisions leading to the formation of four blastomere types (Macromeres, secondary Macromere, Mesomeres and Micromeres);--the differentiation of two syncytial embryonic envelopes during the preoncospheral phase. The outer envelope encloses the vitelline material remnant and three Macromeres among which the secondary Macromere. The inner envelope or embryophore, originates from five or six Mesomeres;--the presence of the oncospheral membrane;--the Phyllobothriidae ontogenesis is similar to that of the Onchobothriidae. By their embryonic features, the Tetraphyllidea are close to the Cyclophyllidea. This similarity suggests a phylogenic relationship between those two Cestoda orders.

The data are given on the morphology of cestodes of the genera Gyrocoelia Fuhrm,. 1899 and Infula Burt, 1939. It has been found that in the spermatheca of the female of G. perversa there are spermatozoids with an elongated head typical for Plathelminthes. In the spermatheca of the female of I. burhini were found spermatids with long tails. The final formation of spermatozoids in I. burhini takes place in the spermatheca. The taxonomic position of the species of Gyrocoelia found in the waters of the USSR has been made more precise: G. polytestis Saakowa, 1952 and Gyrocoelia sp. II Schaldibin, 1960-1961 are reduced to synonyms of Infula burhini and Gyrocoelia sp. I Schaldibin, 1960-1961 to a synonym of G. perversa. The number and size of the hooks of proboscis in the species of the genus Gyrocoelia vary in wide ranges and cannot be used as a taxonomic character. The number of testes and the structure of the egg membrane are constant for the species of this genus.

A comparative description is given of different connective tissue cells and the character of intercellular substance in the parenchyma of two species of cestodes of the order Pseudophyllidea and 4 species of the order Cyclophyllidea. The parenchyma of the cestodes has been shown to be a complex specialized tissue system evolving divergently. The first distinct morphological differences arise at the family level. The direction of the divergent evolution of the parenchyma depends on the development of certain components of intercellular substance, frequencies of individual types of cells and appearance of specific cellular element in it.

The influence of the cestode H. taeniaeformis cysticercus exometabolites on the fibroblasts of their capsule in organ culture was studied. Half of explants were cultured in the presence of cestodes (the ratio between the parasite body weight and the cultural medium volume being 1:10 g/ml). After 2-30 days of cultivation the explants were examined by histological, histoautoradiographic and electron microscopic methods. The influence of cysticercus exometabolites on the culture resembled that of the growth-stimulating factors. The young, actively proliferating fibroblasts were mainly observed in the explants of the capsules cultured in the presence of cysticerci. Among the mature cells, fibroblasts with the predominance of the fibroclastic function were noticed rather than with the function of collagen biosynthesis. It is suggested that the change in the differentiation ways of fibroblasts may be due to some biologically active substrates of the cysticercus to be directed on slowing down the maturation of the connective tissue capsule.

Lipids comprised 37% and 22.1%, respectively, of the day weights of brush border- and vesicle-rich fractions separated by differential centrifugation of isolated H. diminuta tegument. Neutral lipids of both fractions were rich in cholesterol, but also contained small amounts of glycerides, sterol esters, and (in brush borders) free fatty acids. Phosphatidyl ethanolamine was the most prevalent polar lipid in both fractions, and was particularly abundant (63.4% of total polar lipids) in vesicles; sphingomyelin, not previously reported from H. diminuta, was also present. Polar lipids of both tegumental fractions resembled each other but differed from whole worm polar lipids in fatty acid composition. Tegumental polar lipids contained lower levels of long-chain, polyunsaturated fatty acids than reported for corresponding lipids of whole worms.

Out of six fish species examined (Esox lucius, Paracottus kessleri, Perca fluviatilis, Leuciscus leuciscus baicalensis, Coregonus autumnalis migratorius, Thymallus arcticus baicalensis) labrocyte-like cells were detected in Esox lucius, Leuciscus leuciscus baicalensis, Coregonus autumnalis migratotius. The cells contain large metachromatic granules. Histochemical methods revealed in them sulfated and carboxylic acid mucopolysacharides. The amount of labrocyte-like cells in the capsules around plerocercoids of Triaenophrus nodulosis from Esox lucits liver depends on the age of the capsule and that of the plerocercoid. It increases when the connective tissue papsule is forming and decreases again under aging and degeneration of the capsule containing plerocercoid. The amount of labrocyte-like cells in the cestodes capsules of Raillietina increases sharply when they locate in an accidental organ (liver). This demonstrates the acuteness of organ reactivity to a nonspecific helminth.

An electron microscopic study of the larval stages of two Cyclophyllid Cestodes, Anomotaenia constricta and Hymenolepis stylosa shows the presence of a morphogenetic field whose center is located in the scolex. This field stimulates the graduated differentiation of the tegument and associated structures from the scolex to the cercomer.

The processes of spermatogenesis and spermiogenesis in Hymenolepis diminuta were studied by electron microscopy using improved preparative techniques. Spermatogonia (Type A) are characterized by nuclei 3.79 (+/- 0.17) micrometer in diameter, dense cytoplasm packed with free ribosomes and aggregates of mitochondria. After mitoses, certain spermatogonia (Type B) assume syncytial rosettes containing eight nuclei. Primary spermatocytes maintain the rosette syncytium and have large nuclei (4.28 +/- 0.24 micrometer in diameter), smooth endoplasmic reticulum, and polysomes. The secondary spermatocyte is short-lived and is characterized by nuclei (2.0 +/- 0.11 micrometer in diai (2.0 +/- 0.11 micrometer in diameter) and perinuclear membranous lamellae. The syncytial spermatid cluster contains avoid nuclei which condense and elongate to a final diameter of 0.22 +/- 0.04 micrometer. Once elongated, these nuclei become delimited from the syncytium by invaginations of the plasma membrane. During delimitation, cortical peripheral microtubules arise beneath the spermatozoon plasmalemma and a 9 + 1 axoneme extends the length of the mature lance-shaped spermatozoon.