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Taenia hydatigena eggs were investigated for morphological and physiological changes under water stress conditions. Fresh eggs were exposed at 31%, 47% and 89% of relative humidity (RH), and survival, size and ultrastructural changes were accounted up to 365 days of exposition. The article shows how each RH environment affects the vitality of the eggs. Results of this study suggest that T. hydatigena eggs have mechanisms to withstand water stress, indicating that the eggs clustering improves protection against desiccation, and that endogenous metabolism using triacylglycerols play an important role in the maintenance of embryo vitality under low, medium and high relative humidity conditions. This contributes to understanding the water stress resistance mechanism in eggs belonging to Taeniidae family. The findings shown herein have provided a basis to better comprehend basic biology and epidemiology of the cysticercosis caused by T. hydatigena., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Humans are definitive hosts of three species of the Taenia genus, namely Taenia solium, Taenia saginata and Taenia asiatica. The relative novelty of the latter explains the lack of knowledge concerning certain relevant aspects related to this parasite, such as its definite geographical distribution and whether its eggs can infect humans or not. So far, only the eggs of T. solium are known to be infective for humans, producing cysticercosis. Although eggs contain the infective stage, the oncosphere, there is a lack of research on the ultrastructure of eggs of human taeniids. We show, for the first time, the ultrastructure of eggs of T. asiatica by means of SEM and TEM analyses. We detected all the envelopes, namely the egg shell, vitelline layer, outer embryophoric membrane, embryophore, granular layer, basal membrane, oncospheral membrane and oncospheral tegument. Hooks surrounded by myofibrils and glycogen-like particles, the two types of secretory granules of the penetration glands, as well as several nuclei and mitochondria were also revealed in the oncospheres. In addition to the already known structures in eggs from other Taenia species, the presence of two types of small vesicles is described herein, possibly corresponding to exosomes and ectosomes because of their shape and size, which could participate in the host/parasite intercellular communication.

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.

Taenia crassiceps has been widely experimented as a model for in vitro and in vivo studies on drug responses. The purpose of this study was to treat BALB/c mice infected with T. crassiceps strain WFU with commercially available albendazole and to analyze the reduction in parasite infrapopulations. Here, we describe the reduction and apparent damage of T. crassicceps WFU cysticerci in infected mice after antihelminthic drug treatment and subsequent inoculation of those treated parasites into a naïve host. We were able to reduce significantly the parasite counts to 33 and 48% after albendazole treatment for 20 or 25 days and compared with the untreated mice. We also observed morphological damage such as the partial blebbing in the tegument and parenchyma of treated parasites, as well as disorganized musculature and the loss of cell membranes in subtegumental tissue section. However, larvae from albendazole-treated mice inoculated into the next host were able to become re-established in the next murine host due, probably, to the survival of proliferative parasite cells.

Coenurosis is a central nervous system disease of wild and domestic ruminants caused by Coenurus cerebralis, a bladder worm stage of Taenia multiceps). Even in Sardinia island, this metacestode seems to be widespread in sheep (Scala et al. Vet Parasitol 143(3-4):294-298, 2007) where coenurosis is an important health problem (Varcasia et al. Parasitol Res 99(5):622-626, 2006) the last and unique report of coenurosis in cattle was in 1990 (Cubeddu et al. 1990). In the present paper, a case of bovine coenurosis in Sardinia was described 22 years after the first report with a morphological a biomolecular characterization. A 2-year-old Limousine bull was euthanized in the Bolotana (NU) municipality (Central Sardinia). The remote anamnesis achieved from the farmer reporting that the bull showed neurological symptoms from 1 year of age previously classified as nutritional problems by the farm's veterinary. The breeder also says that the bull have by self-produced the skull fracture by hitting a gaff in the farm. The skull was opened and the brain removed and carefully examined showing two coenurus cysts containing clear fluid with numerous scoleces both in the right hemisphere. Morphological features of the cysts and mt-DNA sequencing confirm that the parasites were T. multiceps Coenuri.

The mature Taeniarhynchus saginatus spermatozoon exhibits an apical cone of electron-dense material and one helicoidal crest-like body roughly 50 nm thick. The axoneme is of the 9 + "1" Trepaxonemata pattern. It is surrounded by a periaxonemal sheath of electron-dense material. The cytoplasm is electron lucent and divided into compartments by intracytoplasmic walls of electron-dense material in regions III and IV. The nucleus is an electron-dense cord 60-90 nm thick coiled in a spiral around the axoneme. It reaches the posterior extremity of the gamete where the axoneme is disorganized and is accompanied on all its posterior length by the nucleus. To our knowledge, such a posterior extremity has never been described before in a cyclophyllidean cestode.

The cellular organisation of Taenia ovis oncospheres is interpreted from ultrathin serial sections and transmission electron microscopy following high pressure freezing and freeze-substitution. The surface of a hatched, non-activated T. ovis oncosphere is covered by an oncospheral membrane below which is the tegument bearing microvilli. The basal lamina of the tegument is underlain by broad bands of peripheral somatic musculature. Three pairs of hooks and associated muscles are present in the somatophoric third of the oncosphere. Approximately 19 cells of seven different types were identified which include: (i) a quadri-nucleated syncytium of penetration gland type 1 containing two lateral pairs of cell bodies interconnected by narrow cytoplasmic bridges (PG1); (ii) a quadri-nucleated syncytium of penetration gland type 2 (PG2); (iii) a single-nucleated median mesophoric gland cell; (iv) 10 somatic cells; (v) two germinative cells; (vi) two nerve cells; and (vii) a pair of median somatophoric cells. This study provides a clear understanding of the morphology of T. ovis oncospheres and forms the basis for further investigations into the biology of taeniid oncospheres., (Copyright © 2010 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

Taenia ovis is a cestode parasite infecting primarily sheep as intermediate hosts and dogs as definitive hosts. The first highly effective, recombinant vaccine against a parasitic organism was developed against T. ovis infection in sheep. Three separate host-protective antigens (To16, To18, and To45W) have been cloned from the oncosphere of the parasite. We localize these antigens in the oncosphere by using quantitative immunogold labeling and transmission electron microscopy. The three antigens were uniquely associated with penetration gland cells. The cytoplasm and secretory granules of both penetration gland type 1 and type 2 cells exhibited statistically significant levels of staining for each of the three antigens. The intensity of labeling of the penetration gland type 1 cell was approximately three to five times greater (P < 0.01) compared to the level of staining intensity seen in the penetration gland type 2 cell. In activated oncospheres, secretory blebs were found to contain granules with a structure similar to those observed in the penetration gland cells. The granules within the secretory blebs were shown to stain specifically for the presence of each of the three host-protective antigens. The absence of surface location of the T. ovis antigens suggests that the parasite may not be susceptible to vaccine-induced antibody- and complement-mediated attack until some postoncospheral development has occurred after infection of the intermediate host.

Taeniid eggs contain an infective larval form of the parasite, known as the oncosphere, which has been found to be highly susceptible to attack by the host's immune system and this fact has been exploited in the development of highly effective vaccines. Relatively little is known about the structure of taeniid oncospheres and the localization of host-protective antigens within or on the oncosphere. Here, we briefly review the current state of knowledge of the structure of the oncosphere and present preliminary data on the localization of a host-protective antigen within the oncospheres of Taenia ovis. The precise localization of the antigens, in the context of a detailed knowledge of the ultrastructure of the parasite, may reveal the immune mechanisms by which the taeniid parasites are killed by vaccine-induced immune responses, which, in turn, may provide clues about how vaccines could be developed against other parasitic helminths.

The ultrastructural characters of the mature spermatozoon of Taenia taeniaeformis are described by means of transmission electron microscopy. Materials were obtained from a naturally infected road-killed cat (Felis catus) from La Palma (Canary Islands, Spain). The mature spermatozoon of T. taeniaeformis is a filiform cell, which is tapered at both extremities and lacks mitochondria. It is characterised by the presence of (1) a single spirallised crested body about 140 nm thick, (2) a single axoneme of the 9+'1' pattern of trepaxonematan Platyhelminthes, (3) a twisted (40 degrees ) layer of submembranous cortical microtubules, (4) a periaxonemal sheath surrounding the axoneme, (5) transverse intracytoplasmic walls and (6) a spirallised nucleus encircling the axoneme. The mature spermatozoon of T. taeniaeformis is also characterised by the presence of an apical cone in its anterior extremity and by the disorganisation of the axoneme in its posterior extremity. The ultrastructural characters of the mature spermatozoon of T. taeniaeformis are compared with those of other cestodes studied to date, with particular emphasis on other representatives of the family Taeniidae.

In classical textbooks of parasitology, the mature proglottids of taeniids are depicted as structures in which the individual testis are connected to the vas deferens through the vas efferens system, usually depicted as a network of channels. From our morphological analyses of proglottids in the cestode Taenia crassiceps, we have been unable to identify this channel network. It is unclear how the spermatids are transported from the testes to the vas deferens, as is unresolved the location of the cells responsible for the production of testosterone (Leydig cells) or the possible equivalent of Sertoli cells, necessary for the differentiation process of these cells. In this experimental work, we have examined the ultrastructure of tissues in the vicinity of the vas deferens in mature proglottids obtained from the intestines of hamsters infected with cysticerci from the peritoneum of infected mice. Worm tissues were fixed, processed, and sectioned for transmission electron microscopy. Significant areas of the testis epithelia emitted cytoplasmic projections surrounded by extracellular matrix, where they appear as septated pockets enclosing free axonemes and spermatids. Vas efferens walls are made up of nucleated cells with cytoplasm annealing to each other through cell membrane junctions. Lodged between the junctions are membrane-bound pouches with dense granules found as aggregates or aligned in a semicircular array. The efferens wall exhibits numerous spermatids emerging into the lumen, an observation that suggests the epithelial wall may have the maturing functions of Sertoli cells of vertebrates. Large cells adjacent to the vas efferens contained prominent rough endoplasmic reticulum and large mitochondria, characteristics described for Leydig cells of vertebrates. Our observations suggest that taeniid spermatids are either transported from the testes to the vas system by epithelial pockets or that the epithelial pockets may be cross-sections of a highly coiled vas efferens system.

Objectives: Neurocysticercosis is a common parasitic disease in the CNS in humans caused by the metacestode Taenia solium, with high incidence in developing countries. Albendazole is the drug of choice. However, a wide interindividual variability in the response has been reported. In order to evaluate alternative treatment options, the in vitro efficacy of nitazoxanide, its main metabolite tizoxanide as well as the tizoxanide and albendazole sulphoxide combination was tested against Taenia crassiceps cysts., Methods: T. crassiceps cysts were incubated in culture medium containing different concentrations of nitazoxanide, tizoxanide and albendazole sulphoxide (0.037-0.42 microg/mL). The effect of the tizoxanide and albendazole sulphoxide combination was evaluated in a fixed-concentration ratio (1:1). Isobolographic analyses were used to define the kind of interaction between drugs. Morphological and ultrastructural alterations over the parasite tissue were observed by light and transmission electron microscopy., Results: Nitazoxanide and tizoxanide exhibited cestocidal activity which was time-concentration-dependent. The EC(50) values were 0.15, 0.12 and 0.080 microg/mL for nitazoxanide, tizoxanide and albendazole sulphoxide, respectively. No statistical differences between EC(50) values were found, indicating that nitazoxanide and tizoxanide are equally potent as albendazole sulphoxide. The effect of the tizoxanide and albendazole sulphoxide combination was faster than that observed with each drug alone. Isobolographic analysis showed that the effect of the combination was additive. Nitazoxanide and tizoxanide had an effect on the germinal layer, where lipid droplets were found. Nitazoxanide and tizoxanide produced less damage than albendazole sulphoxide on the germinal layer. After the tizoxanide and albendazole sulphoxide combination, a high accumulation of lipid droplets within the germinal layer of the parasite was found., Conclusions: Our results suggest that nitazoxanide in combination with albendazole could be useful for treatment of cysticercosis infections. Additional in vivo studies are required to confirm this hypothesis.

A 4-year old, male intact, captive-bred chinchilla (Chinchilla lanigera) was presented due to progressive exophthalmos of the right eye over a 5-month period. Ophthalmic examination revealed exophthalmos with dorsal displacement of the right globe. Retropulsion was decreased and a fluctuant, subcutaneous mass could be palpated posterior and dorsal to the central aspect of the zygomatic bone. Transdermal ultrasonography revealed a fluid-filled mass consistent with a cyst located within the ventral right orbit. Computed tomography demonstrated dorsal displacement of the globe, lateral displacement of the zygomatic arch, and numerous mineral-dense foci within the lumen of the cyst. The cyst was removed en bloc by ventral transpalpebral orbitotomy. Histopathology revealed a single capsulated cyst with multiple invaginated protoscolices, characterized by a prominent scolex with refractile hooklets, suckers, and abundant calcareous corpuscles consistent with a Taenia coenurus. Exophthalmos resolved with surgical therapy and there was no evidence of recurrence or postoperative complications over a period of 2 years. To the authors' knowledge, this is the first reported case of an orbital cyst of parasitic origin in a chinchilla.

In this study the cleavage divisions and the ultrastructural analysis of early embryos as well as cellular organisation of infective oncosphere of the anoplocephalid cestode Mosgovoyia ctenoides are described. The early cleavage is unequal and results in the formation of three types of blastomeres: 2 large macromeres containing large electron dense granules, 3 medium-size mesomeres and several small micromeres. In the early stage of oncospheral morphogenesis, formation of three following primary embryonic envelopes takes place: (1) the capsule replaced by thick, rigid outer coat originated form the uterine material secretion, (2) the outer envelope and (3) the inner envelope. The capsule is formed from the vitellocyte material. Two macromeres contribute to the formation of the outer envelope and three mesomeres take part in the formation of the inner envelope. The inner envelope undergoes differentiation into three sublayers: (1) a thick extraembryophoral cytoplasmic layer, (2) an electron-dense embryophore, as a stiff pyriform apparatus, and (3) a thin intraembryophoral cytoplasmic layer containing mesomere nuclei. The oncosphere is located in the extended cupule-like part of the pyriform apparatus. Four egg envelopes surround the mature infective oncosphere of M. ctenoides: (1) a thick outer coat, (2) the outer envelope, (3) the inner envelope with a characteristic pyriform apparatus and (4) the oncospheral membrane. Hook morphogenesis takes place inside six symmetrically arranged oncoblasts, each of which shows a characteristic large nucleus of semi-lunar shape. At the beginning the "hook-forming center" appears in the cytoplasmic part of each oncoblast. It consists of numerous free ribosomes, polyribosomes, mitochondria and Golgi complexes. The hook-forming center is involved in synthesis of a hook primordium, which undergoes differentiation and elongation into the fully developed hook. Mature hook consists of three parts: (1) blade, (2) shank, (3) base, and at the site of its protrusion from the oncosphere, is surrounded by a circular septate junction. Wide bands of hook muscles are attached to the basal and collar parts of the hook. The hook blades project outside the oncospheral body into a large cavity that is delimited by the hook region membrane. In the fully developed oncosphere of M. ctenoides three pairs of oncospheral hooks together with specialized hook muscles form a complex of "hook muscle system", responsible for coordinated hook action. The surface of the infective oncosphere is covered by a thin cytoplasmic layer of oncospheral tegument connected with the so-called "binucleate subtegumental cell", situated deeper in the oncospheral body. Below the cytoplasmic layer are situated wide bands of the somatic musculature responsible for oncospheral body movements. Five major types of oncospheral cells have been distinguished in the infective oncosphere: (1) a binucleate subtegumental cell, (2) a binucleate penetration gland, (3) two nerve cells, (4) numerous somatic cells, and (5) six germinative cells. During development of the oncosphere, changes in the concentration of glycogen and number of lipid droplets were observed. In the early embryos glycogen particles were most abundant in the macromere cytoplasm, whereas in micromeres concentration of glycogen was observed to be lower. In the course of the differentiation of the oncospheral envelopes glycogen was progressively distributed to other parts of the developing embryo. Simultaneously, a great increase in the number of lipid droplets was detected. However, during the preoncospheral phase of development a progressive reduction of lipid droplets was observed. This may indicate that lipids play a role of the energy source for developing oncosphere.

Infections with larvae of Taenia crassiceps are rare in humans and have mostly affected patients with acquired immunodeficiency syndrome. We report the first case of a patient with malignancy (non-Hodgkin's lymphoma) and infection of the subcutis and muscles of the hand and forearm. Surgery and antiparasitic chemotherapy led to a complete cure.

Objectives: Praziquantel and albendazole are currently used for chemotherapeutic treatment of neurocysticercosis. Albendazole has been found to be more effective than praziquantel; however, it is well known that not all patients will show a complete resolution of cysts. Searching for more effective treatments, this study was designed to evaluate the effect of the combination of praziquantel and albendazole sulphoxide in a Taenia crassiceps in vitro model as well as the kind of interaction between both drugs., Methods: In order to determine the concentration that produced 50% effect (EC50), T. crassiceps cysts were incubated in culture medium containing praziquantel (0.005-0.04 microg/mL), albendazole sulphoxide (0.021-0.16 microg/mL) or the combination of praziquantel and albendazole sulphoxide in a fixed-dose ratio (1:1). The experimental concentration (EC50Exp) of the combination was determined from the concentration-response curve constructed from the combined drug treatment. Isobolographic analyses were used to define the nature of the interaction between praziquantel and albendazole sulphoxide. Morphological and ultrastuctural alterations after different treatments over the parasite tissue were observed by light and transmission electron microscopy., Results: The changes in ultrastructure were more marked with the praziquantel and albendazole sulphoxide combination. Also the cysticidal effect of the combination was observed earlier than that of each drug alone. When isobolographic analysis was employed, we found that the experimental EC50 value (0.042 microg/mL) was not significantly different from the theoretical EC50 value (0.035 microg/mL), which indicates an additive interaction between praziquantel and albendazole sulphoxide., Conclusions: Our study suggests that the combination of praziquantel and albendazole sulphoxide could potentially improve the current neurocysticercosis treatment.

Experimental taeniid strobilae from Taenia solium and T. crassiceps (WFU strain) were incubated for 0-72 h in 0, 5 or 20 mM glucose solutions and further exposed for 15 min to the gap junction fluorochrome Lucifer Yellow. Frozen sections were obtained from each worm and observed under an epifluorescent microscope. Worm sections from strobilae incubated with glucose, revealed intense fluorescence in the base of the tegumentary surface, suggesting that this tissue behaves as a gap junction complex. Fluorescence intensity differences between control worms not exposed to glucose and worms incubated with glucose, were highly significant. The results demonstrate that under in vitro conditions, glucose is taken up along the whole strobilar tegument in both taeniid species, suggesting, that although taeniids attached to the duodenum probably take up most of their nutrients directly from the mucosal wall, the capacity for absorbing glucose along the tegumentary surface is always active and may increase the survival capacity of these intestinal worms by promoting glucose absorption at other points in the intestinal lumen.

Polycephalic larvae of Taenia endothoracicus were found from naturally infected gerbils Meriones lybicus in a rural area of Arak, central Iran. A large cyst containing 19 protoscolices was located in the peritoneum, attached to the large omentum. The characteristics of the protoscolices and rostellar hooks confirmed the identification of these larvae as T. endothoracicus.

We studied the ultrastructure of spermiogenesis and of the mature spermatozoon of Taenia parva, an intestinal cestode of the common genet, Genetta genetta. Spermiogenesis in T. parva is characterized by the growth of the axoneme externally to a cytoplasmic extension. After a slight rotation, the free flagellum fuses with the cytoplasmic extension. This pattern corresponds to type III spermiogenesis according to the scheme proposed by Bâ and Marchand. The zone of differentiation lacks both striated roots associated with the centrioles and the intercentriolar body between them. Nevertheless, the flagellar rotation of about 45 degrees is observed in this species. On the other hand, the mature spermatozoon of T. parva, as in other cestodes, is filiform, tapered at both extremities and lacks mitochondria. The presence of a single crest-like body, periaxonemal sheath, and transverse intracytoplasmic walls are also characteristic ultrastructural features. The pattern of spermiogenesis and the ultrastructural organization of the spermatozoon of T. parva are compared with the available data on cyclophyllideans and, in particular, species of the family Taeniidae.

Background: In a previous study, it was shown that growth of evaginated metacestodes occurs in the germinative tissue of the neck by duplication of somatic stem cells. In these specimens, it was not possible to find the mitotic figures required to demonstrate duplication of germ cell lines., Methods: Taenia solium strobilae were collected from the intestinal lumen of outbred hamsters infected orally with 10 metacestodes dissected from naturally infected pigs. Animals were anesthetized 1-10 days postinfection, the small intestine excised, submerged in PBS, and cut open longitudinally. Live Taenias were incubated for 6-8 h in medium containing colchicine or 3H-thymidine, washed, and embedded for electron microscopy. For light microscopy and autoradiography, longitudinal sections were cut from whole blocks and mounted on glass slides. A population of large cells without nuclear membranes and containing discrete aggregates of chromatin were observed apposed to myofibrils in the germinative tissue of the neck. These cells were confirmed by electron microscopy as metaphase mitotic figures, with chromosomes attached to a microtubular spindle, embedded in cytoplasm, without a nuclear membrane, and with characteristic centrioles., Results: Only tapeworms in which 3H-thymidine was injected directly into the worm tissue by microsyringe were positive by autoradiography, demonstrating that in contrast to evaginated metacestodes, intestinal worms do not transport thymidine across the tegument., Conclusions: The results show that differentiating T. solium worms have a subset of stem cells that require passage through a mammalian host to go into mitosis, and that tapeworms grown in an experimental animal do not take up 3H-thymidine in vitro.

This article reviews current knowledge on human and porcine cysticercosis caused by Taenia solium. It highlights the conditions favorable for its prevalence and transmission, as well as current trends in research on its natural history, epidemiology, immunopathology, diagnosis, treatment and prevention. Our opinions on the most urgent needs for further research are also presented.

Background: After a human being ingests a cysticercus, the larval stage of Taenia solium, the cysticercus gradually develops toward the adult parasite. In this paper, we describe the sequential progress of evagination of cysticerci., Methods: Intact cysticerci were obtained from swine muscle, and incubated in bovine bile to stimulate evagination. Dissecting, light, and electron microscopy of whole parasites and histologic sections were used for photographic registers., Results: The first event was the widening of the opening of the bladder wall for the scolex and neck to emerge. The two chambers that conform the cysticercus were identified. Histologic sections provided explanation for the conformation of the spiral canal. The scolex uncoils during evagination but does not turn inside out., Conclusions: The scolex and the neck comprise a different structure from the bladder wall, although they are contiguous.

Intermediate filaments (IFs) make up the cytoskeleton of most eukaryotic cells. In vertebrates, a number of IF proteins have been identified, showing distributions unique to tissue or cell type. Information on helminth IFs is limited to some nematode species. To observe immunofluorescent localization of IFs in helminth tissues, we selected a murine hybridoma clone producing IgM antibody to multiple types of mammalian IF proteins and examined cross-reactivity to helminth proteins. The selected monoclonal antibody (HUSM-9) cross-reacted well with IFs from nematode species such as Toxocara canis, Dirofilaria immitis, Anisakis simplex, and Trichinella britovi; strong immunofluorescence on cryostat sections was detected in the hypodermis, cords, body muscle, smooth muscle of the uterus, and other epithelial structures. In platyhelminths, i.e., adult Schistosoma mansoni, larval Taenia taeniaeformis, adult Taenia crassiceps, and Echinococcus multilocularis protoscolex, the reactivity was weaker than in nematodes, and localized in the body wall muscle and subtegumental tissue. Western blotting of 8 M urea extracts of parasites with the antibody detected a pair of clear bands in nematodes but not in S. mansoni or the cestodes. These results might be explained by sparse distribution of IFs in platyhelminths, or low affinity of the used antibody to platyhelminth IF proteins, or both.

The strobilocercus stage of the cat tapeworm Taenia taeniaeformis is surrounded by a single syncytial sheet of cytoplasm called the tegument. The outer membrane of the tegument covers both the scolex/strobila (S/S) and the bladder portions of the strobilocercus, but only the S/S region is resistant to intestinal digestion. It has been suggested that the glycocalyx, the surface-exposed glycoconjugates of the outer membrane, may serve to insulate underlying surface membrane components from digestion. In this study, we used lectin binding to test the hypothesis that the glycocalyx of the S/S is different from that of the bladder and that this may serve as the resistance mechanism of the S/S to digestion. Biotin-labeled lectins and an avidin-glucose oxidase detection system were applied to whole strobilocerci and to 1-microm epon-araldite plastic-embedded sections. Lectins bound to either both regions of the strobilocerci, to the S/S regions only, or did not bind at all. The restriction of some glycoconjugates to the glycocalyx of the S/S region only is consistent with our hypothesis.

Experimental infections in golden hamsters with viable Taenia solium metacestodes were used to study by light and electron microscopy the implantation site of the adult tapeworm in the intestinal wall. Implantation sites from 3-, 4-, 10-, and 40-day infections were located in the upper third of the duodenum, excised and fixed in Zenker's or Karnovsky's solution, embedded in Polybed resin, and sectioned longitudinally to observe the position of the worm on the intestinal wall. The scolex of the tapeworm was situated between host villi, with the rostellum penetrating the intestinal wall and the suckers entrapping adjacent villi. Serial sections through several whole implantation sites revealed that the worm was anchored to the host by all 4 suckers simultaneously, each of which was located at a different level and had entrapped intestinal villi in its cavity. Host tissue within the suckers was damaged, exhibiting various degrees of cell lysis and necrosis of epithelial and submucosal cells. The tegumentary surface and microtriches of the scolex were well preserved, with occasional coalescence of tegumentary microvesicles in 10- and 40-day-old infections; microtriches were in direct contact with the damaged host tissue. This study is the first morphological and ultrastructural description of the attachment of T. solium to the intestinal wall employing an experimental model, the results of which may contribute to a better understanding of the biology of human tapeworm infections.

In spite of the vast knowledge that exists in the fields of immunology, biochemistry, diagnosis and treatment, the basic facts about the dynamics of the transmission of Taenia solium are incomplete. The present study determines the age at which piglets become infected in a rural community of Mexico, where the climate is divided into the dry and rainy seasons. It was found that piglets become infected during the dry months, not so during the rainy season. They pick up eggs at the age of 2 to 4 weeks and the metacestodes are present in the liver. In older animals aged 4 to 6 months, the larvae were also found in the muscles. In a 6-month-old pig larvae were found in the muscles and brain. These findings may be explained by behavioural studies of free living pigs and climatic conditions.

Aim: To study the spermatocytogenesis of taeniid cestodes at the ultrastructural leaves., Methods: Transmission electron microscopy., Results: The ultrastructural observation on spermatocytogenesis in Taenia solium, T. saginata and T. pisiformis were made by TEM. Two types of spermatogonia; type A and B, as well as the supporting cells surrounding the peripheral of spermatogonia are recognized. The type A spermatogonia are stem cells and the type B are mother cells which produce 16 primary spermatocytes by mitosis for 4 times with the cells unseparated. The primary spermatocytes are characterized by the ribosome masses in the cytoplasm. 32 secondary spermatocytes arranged in roselike were produced by reductive division of primary spermatocytes. The secondary spermatocytes become the spermatid quickly by short time development., Conclusion: The dividing mode of spermatogonia in Taeniid cestodes is mitosis with cells unseparated.

Aim: To study the transformation of taeniid spermatozoon during spermatogenesis on the ultrastructure level., Methods: Transmission electronmicroscopy., Results: This paper was the second part of the ultrastructural observations on the spermatogenesis in Taeniid cestodes: The transformation of the spermatozoon. The 64-spermatid-plasmodium was generated from the secondary meiosis of the 32 rose-like secondary spermatocytes. The transformation of the spermatozoon was a complex process. Firstly, both the cytoplasm and nucleus of the spermatid elongated while the cytoplasm increased and connected to the cytoplasmic mass (cytophore). Secondly, the chromatins of nucleus polymerized to a thread-bundle-like structure. Finally, it detached from the cytoplasm mass and became a mature spermatozoon. The mature spermatozoon was a thread-like structure, about 16.2-18.6 microns in length and 0.35-0.45 micron in diameter. There were two structurally distinct parts: the part with the nucleus was the head and the part without the nucleus was the tail. The head measured about 5-6 microns in length, 1/3 of the total body length and contained an elongated nucleus which twined around the axoneme without mitochondria. The tail was about 11.2-16.6 microns in length. Throughout the core of the tail was an axoneme with typical "9 + 1" structure. The anterior of the tail, just behind the head, were some mitochondria, about 1.6-1.7 microns in total length which twined around the axoneme. The posterior of the tail contained only an axoneme. In cross-section of the spermatozoon, about 46 microtubules were beneath the plasma membrane., Conclusion: The transformation of the spermatozoon is a very complex process.

Evaginated Taenia solium metacestodes dissected from infected pork meat were incubated in vitro in RPMI 1640 medium with tritiated thymidine, washed, and further incubated for various chase periods. Worms were fixed and embedded in Poly/Bed and sections were processed for autoradiography. Results showed that all longitudinal sections had a germinative region located 500-700 mm posterior to the apex of the scolex with tegumentary cytons arranged in staggered columns perpendicular to the tegument. After 6-hr pulse and 0-12-hr chase periods, a large number of labeled cells were found in the parenchyma and tegumentary wall, included were myocytons, calcareous corpuscle cells, flame cells, osmoregulatory channel cells, and, in the medullary parenchyma, labeled undifferentiated round cells with a large nucleus, prominent nucleolus, abundant ribosomes, and no cytoplasmic organelles. These undifferentiated cells were not labeled after 24-hr and 48-hr chase periods, an observation that strongly suggests these cells divide and migrate toward the tegument in a pattern similar to that described for other cestodes. The morphology and localization of these cells support the view that they are stem cells that give rise to the various cell types of the tegumentary wall. The results indicate that T. solium contains a germinative tissue similar to that described in other cestodes, in which stem cells proliferate continuously, differentiate, and migrate to the tegument, constituting the main process by which these worms develop from metacestode to the adult stage.

The gravid proglottids of Taenia saginata from human infection before and after treatment of patient with niclosamide (Yomesan) were used for studies on oncosphere envelope ultrastucture. The envelopes examined were intact after drug treatment. The samples from niclosamide-treated and untreated patients were similar with respect to number and kinds of the protective structures surrounding the oncospheres inside gravid proglottids. Their morphology was generally similar to this described earlier for other taeniid species. Details of the ultrastructure of oncospheral envelopes from niclosamide-treated patients are presented in the paper. Contamination of the environment with eggs from treated patients, particularly in poor sanitary conditions, is discussed.

Among taeniid tapeworms infecting humans through pork or beef, Taenia solium Linnaeus 1758 and Taenia saginata Goeze 1782 have already been known. Based on the morphologic characteristics of adult and metacestodes of Asian Taenia saginata, the third kind of human taeniid tapeworm known to distribute in Asian countries, a new species name of Taenia asiatica is proposed. In addition to the known biology in their intermediate hosts, T. asiatica was different morphologically from Taenia saginata Goeze 1782 in having the unarmed rostellum on the scolex of adult, the large number of 'uterine twigs' and the existence of 'posterior protuberance'. These structures in the gravid proglottids were used as taxonomic keys in taeniid tapeworms for the first time. T. asiatica metacestode (Cysticercus viscerotropica) was different morphologically from T. saginata metacestode (Cysticercus bovis) in having wartlike formations on the external surface of the bladder wall.

An otherwise healthy 15-year-old girl developed an iridocyclitis in her right eye. A contractable living parasite measuring two millimeter could be detected in the anterior chamber, the other parts of the eye remained uninvolved. The patient had close contact with the young dog of the family. By using a viscoelastic substance the parasite could be removed alive without any complications. The tapeworm was found to be too young for having developed the characteristic scolex. Western-immunoblotting gave indirect evidence for infection with Taenia crassiceps, a dog's tapeworm. During an observation period of two years no evidence for any other ocular or general Taenia crassiceps infestations could be found.

Of 5,404 domestic dogs examined for normal and abnormal Taenia pisiformis in Cairo, Egypt, one dog contained 3 triradiate specimens while 3,569 harboured one or more normal cestodes. The study revealed a ratio of one triradiate to 5,620 normal adult worms in the parasite population and a prevalence of 0.02% for the triradiate forms. Polyradiate forms are far less common in this large survey than has been indicated in previous reports.

Crystals of virus-like particles (VLP) are described as occurring in the nuclei of damaged tegumentary cytons from carcasses of Taenia solium metacestodes that had been stripped of their teguments. The VLP are grouped as parallel lines of round particles in an hexagonal packaging of spheroids forming small or large crystals. The individual particles have an external diameter of 36-37 nm and a wall of 5-6 nm thick, which surround a cavity of lower electron density. As identical crystals were also observed in normal tissues of T. solium and of T. crassiceps, it is suggested that both species of cysticerci are normal carriers of a similar species of virus. The possible biological implications of this condition are discussed.

Gossypol, a natural biphenyl compound inhibits Taenia taeniaeformis metacestode development in vivo. In this paper, the direct effect of gossypol on metacestodes was examined. Within 24 hr of incubation at 37 degrees C in greater than or equal to 10(-5) M gossypol, shedding of the tegument from the surface of the metacestodes was observed. There was a significant decrease in [3H]thymidine uptake by T. taeniaeformis in greater than or equal to 10(-5)M gossypol. In addition, NADH lactate dehydrogenase activity of metacestodes was significantly inhibited in greater than or equal to 10(-5) M gossypol. Thus, gossypol has a direct inhibitory effect on T. taeniaeformis metacestodes in vitro.

An 8-year-old girl complained of progressive pain, visual loss and photophobia in her right eye for 1 week. Treatment with local steroids for acute iritis had not been successful. Slitlamp examination revealed a marked cellular and fibrinous inflammatory reaction of the anterior chamber and a whitish, fibrin-like structure on the surface of the iris. There was mild serum eosinophilia and leucocytosis. The suspected organic material was removed surgically. By light and electron microscopy, parts of the wall of a helminthic parasite were discovered, anatomically consistent with the diagnosis of an immature stage of Taenia solium found in cysticercosis. Such cases of intra-ocular parasitosis are described very rarely but might still occur, although there is no history of suspicious typical exposition to parasites. It is important to know that eosinophilia may be insignificant or even absent and that complete surgical removal will be the only successful treatment.

The organisation of five species of cyclophyllidean cestodes (Hymenolepis nana, H. diminuta, H. microstoma, Taenia (Hydatigera) taeniaeformis, Echinococcus multilocularis) has been studied using light and electron microscopy (SEM, TEM). It was found that there is no indication of any internal structure separating the proglottids, which are recognisable superficially. Thus in cestodes there is no metameric segmentation as in annelids. The implications of these findings on the terminology of tapeworm morphology are critically discussed.

Scanning electron microscopy disclosed differences in various areas of the surface of the adult tapeworm, and in larval and adult scoleces of M. endothoracicus. Microtriches with apically crooked spikes were found in the circlet of hooks of the adult tapeworm, and in the area between the outer and inner sucker margins, i.e., in sites important for intestinal attachment. Dimorphic microtriches were present on the inner margin of the suckers and around the genital pore, while the only area to contain dimorphic microtriches in the larva was the surface of the rostellum. An illustration is given of the egg and its fixation to uterine branches.

A study has been made on the fine structure of three postembryonic phases of C. tenuicollis. We observed the differentiation of the villus-like microtriches without a distinct point. A lysis of host cells was caused by a secretion released from vesicles and droplets in the microthrix border. We distinguished 5 types of little-specialized cells during the initial phase of bladder development. The smallest of these cells were persisting oncospheral germ cells. The differentiation of cells terminated with the differentiation of the excretory system in a 16 day-old larva.

Oncospheres of Taenia saginata cultivated in Leibovitz's medium on a cell monolayer from calf kidney developed up to 10th day of in vitro cultivation. Fine and often branched microvilli were observed on their surface. On day 5 of cultivation, the muscle system of hooks turned to a granular matter and on day 7 neither hooks nor their muscle system were found. The tegumental cytoplasm was not formed in the period of 7-60 days of cultivation. On days 7 and 10 of cultivation, a contact of oncospheres with the cells of monolayer was visible. On day 10 of cultivation, an extrusion of a portion of cytoplasm of surface cells filled with minute vesicles occurred. The bonds among cells, particularly in the centre of the oncosphere, were loosened in a 30-day-old culture and the cells were interconnected by long cytoplasmic bridges. Degenerative changes occurred on about day 40 of cultivation. The oncospheres cultivated in pure Leibovitz's medium lost the microvilli on their surface and the original tegumental cytoplasm turned to a fibrous layer already on day 5 of cultivation. Dystrophic changes in cells occurred from day 7 of cultivation and gradually increased.

Ultrastructural observation were made on the host-parasite interface from 1 to 7 days postinfection (DPI) with Taenia taeniaeformis in the rat. Over this period the organism developed from a multicellular oncospheral mass, equivalent in size to a host hepatocyte, into a fluid-filled, grossly visible vesicle, the walls of which showed the arrangement of syncytial tegument, cytoplasmic bridges and subtegumental cell bodies typical of older cestodes. Microvilli, often branched, extended from the free, tegumental surface of the parasite from 1 DPI onwards. Fragments of the microvilli were pinched off distally, and became segmented and distended. Some were seen in intercellular spaces as far as 40 micrometers from the free tegumental surface; others were ingested by nearby host phagocytic cells, and appeared to swell and rupture within phagosomes. Microvillar branching was less frequent after 4 DPI and the microvilli became progressively shorter. By 7 DPI the tegumental surface had become irregular and the microvillar bases were broad and knoblike. Electron-dense deposits were present on the outer membrane of microvilli, the tips of which had become truncated or globular. Although phagocytic host cells were seen in migratory tracks and in contact with some organisms as early as 1 DPI, they caused no detectable damage to the parasites. However, many host cells, including hepatocytes and endothelial cells, were injured or destroyed; their contents contributed to the debris surrounding the parasite at all stages. Inclusions, probably lipid, appeared within the tegument and subtegumental cell bodies from 3 DPI onwards, and similar droplets were seen in adjacent host cells. The great increase in surface area of postoncospheral forms over the first week of infection, augmented by the display of multiple, microvillar projections, may provide not only or the absorption of nutrients required for growth, but also for the enhanced release of factors that affect survival of host cells and stimulate immunological defense mechanisms.

The ultrastructure of the oncospheres of Taenia saginata after treatment with artificial gastric juice is described. After the treatment with the gastric juice, the oncosphere remains in the embryophore. Finger-like processes are formed on the membrane separating the granular layer of embryophore from the oncospheral membrane and micropores arise in the outer unit membrane of the oncospheral membrane. After the treatment with the intestinal juice, the embryophore disintegrates. The oncospheral membrane is again without pores and it is shed off after induction of active movement of the oncosphere. The activity of penetration glands increases: in the first phase, the secretion accumulates beneath the oncospheral membrane and after its shedding there appear granules of other type in the glands. This second phase of secretion seems to be important for the penetration of the oncosphere through the mucosa of the small intestine into the processes. The functional importance of the structural changes observed, the two types of secretion of penetration glands and their relation to pathological changes in the infected organ, and immune reactions are discussed.

Regional variations in the thickness of the tegument, in the morphology of microtriches and mitochondria, in the distribution of dense bodies, smooth micropinocytotic vesicles (SMVs), and coated micropinocytotic vesicles (CMVs) have been shown for the cysticercus of Taenia crassiceps. The number of SMVs and CMVs present in the syncytial layer are in inverse proportion to each other, the former being more numerous in the bladder wall and upper part of the invagination canal and the latter in the lower part of the canal and the rostellar region. Tegumental cells contain numerous granular endoplasmic reticulum-Golgi complexes involved in the synthesis of both primary lysosomes and dense bodies. Vesicles characteristic of various stages of heterolysosomes are present and show regional variations in numbers and size. Acid phosphatase activity (EC 3.1.3.2) is present on the tegumental surface, and within the Golgi complex, primary lysosomes, and heterophagosomes of the tegumental cells. CMVs are reported for the first time in the tegument of any helminth and have characteristics similar to CMVs in other tissues. T. crassiceps, therefore, because of the presence of both SMVs and CMVs, is a unique model system for the study of basic mechanisms of endocytosis.

By scanning electron microscopy we found heteromorph microtriches in the tegumental surface of the praeadult and its bladder. But this polymorphism is caused by three unimorph parts, namely the head region, the midbody and the bladder. The types of microtriches are heterogeneous in regard to the shape (from conical to cylindrical), the size (from 0.37 to 4.5 micron in length and 0.055 to 0.092 micron in diameter) and the density (from 6.3 to 25 microtriches/micron 2). An attempt was made to determine the relative increase in the tegumental surface of the cysticercus of T. saginata. The relation of actual surface area to a corresponding area without microtriches is OF = nA + 1/1 - nB. In this study, the factor of the increase in the tegumental surface (OF) ranged from the head region (6.3x) to the midbody (1.4x -1.7x) and the bladder (21x). By transmission electron microscopy fine threads were demonstrated in the apical surface of the microtriches. These fine threads raised the adhesive function of the microtriches in the course of the infection of the final host as well as in the migration in the digestive tract. A relation between shape, size and density of the microtriches and the body volume is postulated.

The tegument of larval Taenia crassiceps possesses a surface coat rich in both neutral and acidic carbohydrates. Neutral glycans were detected in Golgi vesicles of the tegument perikarya, vesicles of the distal tegument, and on the surface of the plasma membrane. Autoradiographs indicated the tegument perikarya as major sites of 3H-galactose incorporation into acid-insoluble macromolecules. The labeled material is subsequently translocated to more superficial regions of the tegument, then concentrated in the brush border. Loss of radioactivity is appreciable within 6 hr of the synthesis of this material, indicating continual replacement of this tegument surface component.

The surface of a racemose cysticercus from the human brain was studied by scanning electron microscopy and the tegument of the cyst by transmission electron microscopy. The surface of the larva is covered by microvilli of uniform shape and size. The glycocalyx of the microvilli bears knotlike areas positive for acid mucopolysaccharides. Microvilli are interconnected by a fine, electron-dense network. The tegumental and subtegumental tissues vary in thickness from one region to the next, and the tissues below the vesicular layer are scattered irregularly, in a seemingly disordered manner.