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At least 109 records · Page 6Linked to original sources
PubMed1975

Tricarboxylic acid cycle enzymes in the plerocercoid of Ligula intestinalis (Cestoda: Pseudophyllidea).

All enzymes of the tricarboxylic acid cycle are present in subcellular fractions of the plerocercoid of Ligula intestinalis but the low activity of aconitase and malate dehydrogenase in the forward direction suggests that the complete cycle may be of questionable importance to the parasite. As in other helminths and intertidal molluscs, succinate, formed via a partial reversal of the tricarboxylic acid cycle, is a major end-product of anaerobic glucose degradation.

Aconitate Hydratase↗
PubMed1975

In vitro hatching of the tapeworm Moniezia expansa (Cestoda: Anoplocephalidae) and some properties of the egg membranes.

In vitro studies revealed that the hatching of oncospheres of Moniezia expansa requires the mechanical breakage of the eggshell and subshell membrane and enzymic digestion of the pyriform apparatus. Removal of the outer two egg membranes elicits the activation of most oncospheres. Between pH 5.0-7.8, there is no significant difference in numbers of oncospheres activated by eggshell removal and the addition of sodium bicarbonate has no effect. Solutions of more extreme pH values (2.0 and 10.0) are harmful and render oncospheres immobile. The subshell membrane forms a barrier to the passage of water in an osmotic gradient and to several molecular and ionic substances. Between the eggshell and subshell membrane is a layer of droplets which have a strong affinity for Sudan stains and which are partially removed by lipase. The eggshell is resistant to a variety of proteolytic enzymes, amylases and lipase. The pyriform apparatus is digested by chymotrypsin and pepsin, though not by trypsin. Both eggshell and pyriform apparatus are dissolved by solutions of sodium sulphide and sodium hypochlorite, indicating that their structures are stabilized by disulphide bonds and other covalent linkages.

Animals↗
PubMed1977

The effect of cortisone acetate on the metabolism of Hymenolepis microstoma (cestoda:cyclophyllidea).

Hymenolepis microstoma grown in mice, treated with 1.25 mg cortisone acetate every second day, are heavier and have a significantly higher glycogen content than those in control mice. The dry/wet weight ratio and protein content however are unaffected. It is suggested that the increase in glycogen reserve and weight in H. microstoma from cortisone-treated mice is due to an immunosuppressive effect and better nutritional environment rather than hormonal action. Inclusion of 0.1 mg of cortisone per 100 ml of culture medium produces no change in worm weight in vitro. Single worm infections result in 100% recovery, but 30 worm infections provoke a rejection process which can be suppressed partially by administration of cortisone acetate.

Animals↗
PubMed1977

The fine structure of spermatogenesis in Hymenolepis diminuta (Cestoda) with a description of the mature spermatozoon.

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.

Animals↗
PubMed1975

The histochemistry and fine structure of the embryophore of Shipleya inermis (Cestoda).

The embryophore (inner capsule) of the tapeworm Shipleya inermis was studied with histochemistry and electron microscopy. It was found to be unique for the cestodes in that it has a laminated construction. During development lamina are added until there are 10 which are arranged in an irregular zig-zag pattern. The embryophore is positive to tests for acid and alkaline phosphatase, and the Hales test for acid mucopolysaccharides. Permeability of tapeworm egg coverings is discussed.

Acid Phosphatase↗
PubMed1987

The structure, composition, formation and possible functions of calcareous corpuscles in Trilocularia acanthiaevulgaris Olsson 1867 (Cestoda, Tetraphyllidea).

Mature calcareous corpuscles in the juvenile (stomach) worms of Trilocularia acanthiaevulgaris comprise a number of concentric lamellae interspersed with areas of flocculent material. Each lamella is composed of a pair of membranous rings to which amorphous, non-crystalline material is attached. The process of corpuscle formation is intracellular, beginning with the autophagic break-down of the cytoplasm to produce a central vacuole within a parenchymal cell. The vacuole enlarges until only a thin layer of cytoplasm remains at the periphery and the nucleus is displaced to one end of the cell. Paired, concentrically arranged membranes are laid down beneath the peripheral cytoplasmic layer and eventually occlude the central vacuole. X-ray analysis of the corpuscles indicates the presence of calcium, phosphorus, sulphur, zinc and molybdenum, with the major peaks representing calcium, phosphorus and sulphur. Calcium appears to be bound to the lamellae rather than associated with the material between lamellae. The possible functions of the corpuscles are discussed in relation to the biology of T. acanthiaevulgaris and its developmental sequence in the dogfish gut.

Animals↗
PubMed1987

The concept of specificity in the procercoid-copepod system: Bothriocephalus claviceps (Cestoda) a parasite of the eel (Anguilla anguilla).

This paper describes experimental work on parasite specificity in the copepod-procercoid system of Bothriocephalus claviceps. Two criteria were used to characterize five potential host species Macrocyclops albidus, Macrocyclops fuscus, Eucyclops serrulatus, Acanthocyclops robustus and Macrocyclops viridis viridis. The first criterion involves susceptibility of the copepods to infection. The results show random or aggregative distributions and variable susceptibilities according to the species. We observed an ethological barrier to infection in M. viridis viridis and M. fuscus. The second criterion involves the growth and development of the procercoid. Three factors modify the profiles of the growth curves: host species, sex and intensity of infection. The growth of the procercoids is density-dependent, whereas their development is independent of density. This last characteristic is interpreted as a factor favouring the aggregation of procercoid populations. The two most susceptible hosts are M. albidus and A. robustus.

Anguilla↗
PubMed1980

An ultrastructural study of the microtriches of adult Proteocephalus tidswelli (Cestoda: Proteocephalidea).

Ultrastructural observations on adult Proteocephalus tidswelli revealed a marked microtrichial polymorphism. Structural and dimensional variations of microtriches between different regions of the strobila and scolex, as well as within the same region, were observed. The authors suggest that microtriches are involved in a diversity of functions, and possible functional activities are discussed.

Animals↗
PubMed1980

The common vole, Microtus arvalis Pall. as intermediate host of Mesocestoides (Cestoda) in Germany.

Tetrathyridia of Mesocestoides leptothylacus Loos-Frank, 1980 were found in 1.4% of 513 common voles (Microtus arvalis) in a district of Southwest Germany where foxes (Vulpes vulpes) are frequently infected with this tapeworm. The tetrathyridia measured 1 to 1.5 mm in length and 0.5 to 1 mm in width. When injected intraperitoneally into white mice, jirds, or common voles, the tetrathyridia did not multiply. Cats fed with the larvae shed proglottids from the 21st day onwards. In one experimentally infected silver-fox proglottids were passed from day 12 onwards. One human subject infected twice with tetrathyridia of M. leptothylacus, did not develop patent infections. One common vole from another district contained tetrathyridia of a Mesocestoides species, which is rarely found in indigenous foxes and which is characterized by a broad-oval cirrus pouch with a much convoluted cirrus.

Animals↗
PubMed1990

An ontogenetic study of the cholinergic and serotoninergic nervous systems in Trilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea).

The localisation and distribution of the cholinergic and serotoninergic components of the nervous system in the plerocercoid, adult and free proglottis stages of the tetraphyllidean tapeworm Trilocularia acanthiavulgaris were determined by enzyme histochemical and immunocytochemical techniques. The central nerve ring (CNR) in the scolex contains two lateral ganglia and gives rise to five pairs of longitudinal nerve cords (LNC's; three lateral, two median). The nerve cords run posteriorly throughout the bodies of the plerocercoid and adult worms and the free proglottis. Nerves from the CNR and accessory lateral LNC's pass to the bothridia, where they give rise to extensive nerve plexuses. As the individual proglottides develop along the strobila, a small nerve ring forms at the anterior end of each proglottis; within the nerve ring, distinct bilateral ganglia develop prior to the release of the proglottis. All ten LNC's are present in the free proglottis. The genital atrium and cirrus sac are innervated by cholinergic and serotoninergic elements. The cholinergic nervous system predominates in the CNS within the scolex, whereas there is a larger population of 5-HT-immunoreactive nerve cells associated with the LNC's and segmental ganglia along the strobila and within the free proglottis.

Animals↗
PubMed1990

Oogenesis in the free proglottis of Trilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea).

The early (ovarian) stages of oogenesis in Trilocularia acanthiaevulgaris have been studied by light microscope histochemistry and transmission electron microscopy. The process proceeds as far as meiotic prophase in the primary oocyte. The oogonia and early immature primary oocytes occupy the anterior and outer edges of the ovary and are typically undifferentiated cells, showing a high nucleo-cytoplasmic ratio. The scant cytoplasm is packed with free ribosomes and contains a small number of mitochondria and a few short strands of granular endoplasmic reticulum (GER). The oogonia undergo a number of mitotic divisions, marked by the presence of centrioles. The immature primary oocytes enter meiotic prophase, as evidenced by the appearance of nuclear synaptonemal complexes. The maturing primary oocytes, which occupy the inner, central region of the ovary, undergo a growth phase that is accompanied by an increased nucleolar volume and export of RNA to the cytoplasm via nuclear pores, and by an increase in the number of mitochondria. A GER network develops and, together with the Golgi complexes, is involved in the production of a small number of cortical granules. The GER often takes the form of concentric cisternae. Numerous lipid droplets are also present in the cytoplasm. The mature primary oocytes predominate in the posterior region of the ovary, near the oviduct. They represent a resting phase in development, in which cellular activity is minimal. Lipid droplets are abundant and the cortical granules remain in more central regions of the cell and do not migrate to the periphery of the cell. The ovary contains a second, non-germinal type of cell, the follicle cell. The cell body is smaller in size than the oogonia, and cytoplasmic processes from it ramify around the periphery of the ovary. The different cell types within the ovary are embedded in a cytoplasmic matrix that contains a number of organelles.

Animals↗