The ultrastructure of taeniid cestode oncospheres and localization of host-protective antigens.

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.

Schistosoma haematobium: histochemistry of glycogen, glycogen phosphorylase a and glycogen branching enzyme in niridazole-treated females.

The body posterior to the ovary of Schistosoma haematobium females was investigated. Glycogen, glycogen phosphorylase a (EC 2.4.1.1) and glycogen branching enzyme (EC 2.4.1.18) activities were detected in the subtegumental muscle system, parenchyma and mature vitelline cells, whereas no activities were detected in the tegument and immature vitelline cells of the parasite. Administration of a single niridazole dose of 250 mg kg-1 to the pouched mouse (Saccostomus camestris) produced the following changes in S. haematobium females: a relatively rapid depletion of glycogen stores due to disruption of the absorptive surface of the parasite, and to an increase in the activity of glycogen phosphorylase a; a reduction in the phosphorylase a to phosphorylase b-conversion capacity of glycogen phosphorylase phosphatase (EC 3.1.3.17); a decrease in glycogen branching enzyme activity; and a relatively rapid degeneration of parasite cells possibly due to their loss of endogenous energy reserves.

Ultrastructure of oncospheral hook formation in the nematotaeniid cestode, Nematotaenia dispar (Goeze, 1782).

Ultrastructural characteristics of oncospheral hook morphogenesis in the nematotaeniid cestode, Nematotaenia dispar, are described. The primordia of embryonic hooks appear in the advanced phase of the pre-oncosphere in 6 specialised hook-forming cells or oncoblasts. Each hook primordium, situated near an invaginated part of the nucleus, is surrounded by numerous free ribosomes, mitochondria and extended Golgi regions. Simultaneously with the hook primordium elongation and transformation into a blade, handle and base, the hook material differentiates into an electron-dense cortex and a less dense, inner, crystal-like core. The exit of the blade of the mature hook, protruding from the oncosphere, is surrounded by a circular, septate desmosome and 2 rigid, dense rings on either side. The pattern of oncospheral hook morphogenesis in N. dispar is compared with that of 2 previously examined cyclophyllidean cestodes, Inermicapsifer madagascariensis and Catenotaenia pusilla.

Differentiation and ultrastructure of oncospheral and uterine envelopes in the nematotaeniid cestode, Nematotaenia dispar (Goeze, 1782).

The oncospheral envelopes of infective eggs in Nematotaenia dispar include the outer envelope with 2 sublayers, the inner envelope with a fibrillar embryophore and 2 cytoplasmic sublayers, and the oncospheral membrane. They differentiate from 3 primary embryonic envelopes, capsule, outer and inner envelope. The uterine envelopes are formed around the early embryos by processes of uterine epithelial cells, which surround the capsules. They degenerate rapidly in later stages; however, some structural components of the uterine envelopes were still visible in gravid proglottids as flattened perikarya with pyknotic, lobate nuclei, residual membranous structures and cellular debris situated usually between eggs. The following ultrastructural features of oncospheral envelopes differentiation appear to be characteristic for N. dispar: (1) lack of the outer capsule or shell in the fully mature eggs; (2) bi-layered structure of the outer envelope and tri-layered structure of the inner envelope; (3) absence of hook region membrane resulting probably from its early disintegration; (4) presence of small vesicles or "pits" incorporated into the inner envelope plasma membrane; (5) presence of densely packed microtubules in the external layer of the inner envelope; (6) changes in number of mitochondria and free ribosomes in the external and internal layers of inner envelope during egg maturation; and (7) probable "passage" of mitochondria and free ribosomes through the embryophoral pores in the developing eggs.

Differentiation and ultrastructure of the paruterine organs and paruterine capsules, in the nematotaeniid cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a parasite of amphibians.

Three types of egg-protecting envelopes of parenchymatic, uterine and embryonic origin have been distinguished in the cyclophyllidean cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a type species for the genus Nematotaenia and the family Nematotaeniidae. The present paper deals with the parenchymatic envelopes, which originate from the modified medullary parenchyma and are represented in this species by the paruterine organs and paruterine capsules. In pregravid proglottids they are composed of clongated myocytons, myofibrils and membranous anucleate cellular processes, containing a large amount of lipid droplets and some calcareous corpuscle cells. These cellular elements (CE) are separated from each other by abundant extracellular matrix (ECM), which consists primarily of an electron lucent ground substance with fine filaments embedded in it. The paruterine capsules of gravid proglottids are surrounded from the outside by a typical medullary parenchyma and are lined by a layer of the connective tissue. The paruterine organs and paruterine capsules show similar ultrastructure. During their histogenesis, all cellular elements undergo extensive flattening, followed by cellular deterioration, with simultaneous reduction in CE/ECM ratio. In the late gravid segments, paruterine capsule walls are very thick and consist of membranous sheets with large amounts of lipid droplets, which cause the cytoplasmic sheets to bulge. Ultrastructure of various types of parenchymatic envelopes in representatives of different cyclophyllidean families, such as paruterine organs in Nematotaeniidae and Mesocestoididae, uterine and parenchymatic egg capsules in Anoplocephalidae (Linstowiinae and Inermicapsiferinae, respectively), is compared.

Vitellocytes and vitellogenesis in cestodes in relation to embryonic development, egg production and life cycle.

Vitellocytes have two important functions in cestode embryogenesis: (1) formation of hard egg-shell (e.g. Pseudophyllidea) or a delicate capsule (e.g. Cyclophyllidea), and (2) supplying nutritive reserves for the developing embryos. During evolution any of these two functions can be reduced or intensified in different taxa depending on the type of their embryonic development, degree of ovoviviparity and life cycles. Within the Cestoda, there are three monozoic taxa with only one set of genital organs: Amphilinidea, Gyrocotylidea and Caryophyllidea. In these monozoic taxa and some polyzoic groups with well developed vitellaria (e.g. Pseudophyllidea, Trypanorhyncha) a single oocyte [=germocyte] and a large number of vitellocytes (up to 30) are enclosed within a thick, hardened egg-shell, forming a type of eggs typical for the basic pattern of Neodermata. Only one type of egg-shell enclosures, the so-called 'heterogeneous shell-globule vesicle' is common for the above mentioned cestode taxa. Each membrane-bounded vesicle of mature vitellocytes contains numerous electron-dense shell globules embedded in a translucent matrix. In free-living Neoophora and Monogenea there are two types of vesicles with dense granules; the second is considered to be proteinaceous reserve material. Within the Cestoda, the numbers of vitellocytes per germocyte are reduced in those taxa forming eggs of the 'Cyclophyllidean-type' (e.g. Cyclophyllidea, Tetraphyllidea, Pseudophyllidea). This is particularly evident in Cyclophyllidea; for example, in vitellocytes of Hymenolepis diminuta (Hymenolepididae) there are numerous vitelline granules of homogeneously electron-dense material; in Catenotaenia pusilla (Catenotaeniidae) there are three large, homogenous vitelline vesicles, while in Inermicapsifer madagascariensis (Anoplocephalidae) there is only one large vitelline vesicle, containing homogeneously electron-dense material, which occupies most of the vitelline cell volume. In this respect the Tetraphyllidea and Proteocephalidea, in forming eggs that lack a hard egg-shell, hold an intermediate position. A comparison of interrelationships which exist among types of vitellocytes, vitellogenesis, types of embryonic development, ovoviviparity and life cycles indicates parallelisms and analogies in adaptation to the parasitic way of life in different groups of cestodes. Knowledge on cestode vitellogenesis may also have an important applied aspect. Vitellocytes, due to their high metabolic rate, represent a very sensitive target for analysing effect of anthelminthic drugs upon the egg formation (ovicidal effects); rapid degeneration of vitellocytes is usually accompanied by a cessation of egg production.

Schistosoma mansoni: the chemical nature of the secretions produced by the Mehlis' gland and ootype as revealed by cytochemical studies.

The 'secretory pathway' of the Mehlis' gland secretion as well as the maturation of the secretory granules are described. The secretions produced by the Mehlis' gland and the distal ootype in Schistosoma mansoni were identified as neutral glycoproteins. They were both periodate reactive, stained with phosphotungstic acid at low pH, and sensitive to the proteolytic action of papain. The secretions did not strain with both the low-iron diamine and the high-iron diamine methods for the presence of acidic glycoconjugates, and they did not contain a detectable level of sulphydryl groups. The possible role of the secretion from the Mehlis' gland in egg-shell formation is discussed.

Systematic position and phylogenetic relationships of the family Omphalometridae (Digenea, Plagiorchiida) inferred from partial lsrDNA sequences.

The phylogenetic relationships and systematic position of the digenean genus Omphalometra Looss, 1899 and several other closely related genera, have always been controversial and opinions of different authors on the systematic rank and content of this group have varied greatly. Molecular analysis based on the partial sequences of the large subunit ribosomal DNA gene of representatives of the genera Omphalometra, Rubenstrema and Neoglyphe as well as previously published sequences of members of five families of Plagiorchioidea, has demonstrated: (1) close phylogenetic relationships between these three genera, and (2) a strong support of their position within the family Plagiorchiidae as a well-defined separate clade considered here as a subfamily Omphalometrinae. Molecular data do not support the close affinities of the members of Omphalometrinae and genus Opisthioglyphe as has been suggested by majority of previous authors. Among Omphalometrinae, Omphalometra flexuosa (a parasite of moles, Talpidae) occupies a basal position in relation to Rubenstrema exasperatum and Neoglyphe locellus (both parasitic in shrews, members of the more evolutionary advanced family Soricidae). An extremely low level of lsrDNA sequence divergence between Neoglyphe and Rubenstrema suggests very close phylogenetic relationships of these two genera. Results of the molecular analysis are briefly discussed in comparison with the previously published systems.

Intraspecific variability among NADH dehydrogenase subunit 1 sequences of Taenia hydatigena.

This paper describes intraspecific variability of the partial sequences of the mitochondrial ND1 gene among isolates of Taenia hydatigena from pigs in Poland, Ukraine and Wales. The differences between studied isolates ranged from 0.4 to 5.5%, which exceeds the variability within the same fragment between the different genetic variants of Echinococcus multilocularis and is comparable with the variability between the most closely related strains (G5/G6/G7) of E. granulosus. The biggest difference (5.5%) was found between the geographically most distant Ukrainian and Welsh samples of T. hydatigena while the samples collected from the neighbouring locations in Poland, were most similar to each other.

Scanning electron microscopy of the rare nematode species Pterygodermatites bovieri (Nematoda:Rictatuliriidae), a parasite of bats.

External morphology of the nematode Pterygodermatites bovieri (Blanchard, 1886), a very rare parasite of bats in the Palaearctic region, was studied by scanning electron microscopy. Special attention was paid to the cephalic end structure and cuticular armament, which are of great systematic importance in this group of nematodes. The mouth opening of P. bovieri is subterminal and oriented dorsally. Numerous sclerotized denticles, arranged in two rows, are situated in the buccal cavity around the mouth opening. They are better developed in its ventral part. In females there are 12-14 ventral denticles. Cephalic papillae are arranged in two rows: internal (six papillae--two dorsal, two lateral and two ventral) and external (four papillae). Amphids are small, situated close to lateral, cephalic papillae of the internal row. Males possess 40-41 cuticular combs in each ventro-lateral plate row, and, in addition, a short row of four ventral, unpaired precloacal fans. Females in our material possessed 68 cuticular elements represented by combs and spines, in each row. Changes of the cuticular elements shape along the nematode body length are described. Results of SEM observations are compared with previous descriptions of P. bovieri based on the light microscopical observations.

[Comparative studies on the ultrastructure, homology and analogy of egg envelopes in trematodes and cestodes]. / Badania porównawcze nad ultrastruktura homologia i analogia otoczek jajowych u przywr i tasiemców.

The origin, differentiation and functional ultrastructure of egg envelopes surrounding developing and mature miracidia of Schistosoma mansoni and that of developing and mature coracidia of Bothriocephalus clavibothrium have been examined by means of electron microscopy and cytochemistry. Results obtained on these two species were compared with data from our previous studies on the ultrastructure of egg envelopes in different cyclophyllidean (Hymenolepididae, Taeniidae, Anoplocephalidae, Davaineidae) and proteocephalidean cestodes. In the mature infective egg, the three main egg envelopes (the egg-shell, and the outer and inner envelope) that surround the larvae (miracidia of Digenea, coracidia of Pseudophyllidea, and hexacanths of Cyclophyllidea and Proteocephalidea), show evident similarities in their origin, functional ultrastructure and chemical composition. Conclusions of this comparison, concerning analogy and homology in egg envelopes of trematodes and cestodes, are drawn and discussed.

Transmission electron microscope studies on the oncospheral envelopes of Taenia saginata after niclosamide treatment.

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.

Host--protozoans--bacteria--fungi interrelations in the mouths of patients with systemic illnesses.

The aim of this work was to study clinical changes and microorganisms in mouths of three patient groups: with congenital disorders (Cd), dialyzed (D) and control (C). Fifty five patients, 20 to 62 years old were assessed. Swabs and samples of periodontal tissue were used for microscopical study to detect of protozoans and for bacterial and fungal cultures. E. gingivalis and T. tenax were found in all groups. Three out of Cd patients were infected with Acanthamoeba sp.. Fecal bacteria were more often found in D than Cd. In all 30-40 years old D patients, fecal bacteria and various strains of C. albicans occurred. We found that systemic diseases favour instabilities in mouths changing interrelations between protozoa, bacteria and fungi. It may increase risk of clinical complications.

[Spermatogenesis of Bothriocephalus clavibothrium Ariola, 1899 (Cestoda: Pseudophyllidea)]. / Etude de la spermatogénèse de Bothriocephalus clavibothrium Ariola, 1899 (Cestoda: Pseudophyllidea).

The processes of spermatogenesis and spermiogenesis in the Pseudophyllidea Cestode Bothriocephalus clavibothrium were studied by light and electron microscopy. Spermatogenesis is for rosette type. The rosettes of secondary, tertiary and quaternary spermatogonia, primary and secondary spermatocytes and spermatid clusters are all resulting of a series of six incomplete, synchronous divisions (4 mitosis and 2 meiotic kinesis). The 64 nuclear syncytium of spermatids, during spermiogenesis process gives 64 mature spermatozoa, all originating from a single primary spermatogonium. The sperm differentiation is characterized by: 1. -- Formation of the differentiation zone containing an intercentriolar body and two basal bodies of the future axonemes; 2. -- Formation of a cytoplasmic expansion and induction of two flagella; 3. -- Migration of nucleus into medial cytoplasmic expansion inducing progressive longitudinal fusion of the later with two adjacent flagella into a single spermatozoon body. The filiforme spermatozoa of B. clavibothrium are about 300 micrometer long and their main components are . the nucleus, two axonemes, cortical microtubules and cytoplasm rich in beta-glycogen particles.