The neuro-glandular brain of the Pyramicocephalus phocarum plerocercoid (Cestoda, Diphyllobothriidea): Immunocytochemical and ultrastructural study (original) (raw)
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Fine structure of nervous system in plerocercoid Ligula intestinalis (Cestoda: Diphyllobothriidea)
Invertebrate Zoology, 2010
The fine structure of the nervous system in plerocercoid Ligula intestinalis (Diphyllobothriidae) has been studied. The ultrastructure of the cerebral ganglion, the main nerve cords and peripheral nervous system has been described. The cerebral ganglion has complicated microanatomy. It consists of symmetric pair frontal and lateral lobes connected by the massive median commissure, and ventral azygos lobe, located in the center and on the ventral surface of the commissure. Two crossed ventral nerves are originated from the unpaired median (ventral) lobe. It was found, that the neurons in the lateral lobes and the commissure have asymmetrical position (localization neurons in the lateral lobes and the commissure has dorso-ventral polarity): large neurons (2040 µm) are concentrated on the dorsal surface of the cerebral ganglion. We found four types of neurons with different fine structure and size, peripheral neurosecretory cells and undifferentiated cells. Three types of synaptic contacts have revealed in neuropiles. Giant axon occurred as part of the main cord. On the surface membrane of the giant axon are numerous incoming synapses. The peripheral nervous system consists of numerous compact bunches of nerve processes taking place along the longitudinal and dorso-ventral muscle fibers. Also three types of sensory organs were found in the tegument: one type a ciliate and two types unciliate receptors. Comparative analysis of nervous system organization in representatives of the two orders Diphyllobothriidea and Bothriocephalidea showed that the cerebral ganglion L. intestinalis possesses bilateral symmetry, characterized by the presence of the ventral lobe, ventral nerves and the dorso-ventral polarity in the arrangement of neurons and exiting nerves. On the contrary, the cerebral ganglion of Triaenophorus nodulosus (Bothriocephalidea) has a double-beam symmetry: it has symmetrical lobes in ganglion with symmetrical dorsal and ventral nerves, lack of lobe in the median commissure, and send symmetrical dorso-ventral rootlets in the bothria. Our data confirm the belonging of the studied species to different groups and support the idea of separation Pseudophyllidea sensu lato into two new orders Diphyllobothriidea and Bothriocephallidea.
Invertebrate Zoology, 2017
The ultrastructure of the tegument, glands and sensory organs of Pyramicocephalus phocarum (Cestoda: Diphyllobothriidea) have been studied. Three types of the microthriches are found, which have a specific distribution on the scolex and body. A welldeveloped basal lamina contained radial anchoring fibrils; they are associated with the microfibrills of the lamina reticularis and form regular cross-links. In the tegument, we have found six types of sensory organs and also terminal pores of the frontal glands. It has been shown that sensory endings and secretory pores are co-localized in the bothria tegument: 30 pores and 50 sensory endings were found in one section. Frontal glands are located in the parenchyma of the scolex and body; glands are well-developed and have intensive eccrine secretion. Comparative ultrastructural analysis of four diphyllobothriidean species shows similarity in the ultrastructure of microtriches and frontal glands in the plerocercoids of P. phocarum and Diphyllobothrium latum.
Parasitology Research, 2009
This study is the first detailed study of the organisation of the neuromuscular system of Cyathocephalus truncatus (Cestoda, Spathebothriidea). Five techniques have been used: (1) immunocytochemistry, (2) staining with TRITC-conjugated phalloidin, (3) NADPHdiaphorase histochemistry, (4) confocal scanning laser microscopy and (5) transmission electron microscopy. The patterns of nerves immunoreactive (IR) to antibodies towards serotonin (5-HT) and the invertebrate neuropeptide FMRFamide are described in relation to the musculature. The patterns of NADPHdiaphorase positive nerves and 5-HT-IR nerves are compared. The fine structure of the nervous system (NS) is described. The organisation of NS in the non-segmented, polyzoic C. truncatus differs clearly from that in the nonsegmented, monozoic Caryophyllaeus laticeps and shows distinct similarities with the NS in pseudophyllidean cestodes. This supports the hypothesis that taxon Caryophyllidea and Spatheobothriidea form independent lineages within Eucestoda.
Doklady Biological Sciences, 2021
Abstract The excretory system ultrastructure and immunocytochemistry have been investigated in the plerocercoid Pyramicocephalus phocarum . It has been shown that P. phocarum has independent terminal cells, cyrtocytes. The entire canal system is a single undivided syncytium, which includes nephridial funnels of the terminal tubules, and peripheral and central canals. The nephridial funnel and cyrtocyte form a filtration complex of the protonephridial type. In the caudal region, several peripheral canals open into a deep fold of the tegument, the urinary bladder. The excretory pores are separated from the tegument by annular septate desmosomes. There are no cell junctions inside the excretory system. The presence of the F-actin ring and the expression of non-synaptic serotonin in the collar area have been detected in cyrtocytes by immunocytochemistry methods.
"N. M. Biserova and I. A. Kutyrev Biology Bulletin, 2014, Vol. 41, No. 3, pp. 242–250 For the first time, the potential immunomodulators prostaglandin E2 and γaminobutyric acid (GABA) have been revealed in the plerocercoid Diphyllobothrium dendriticum, which is a parasite in the tis sues and abdominal cavity of the Baikal omul Coregonus migratorius. The localization of immunomodulators in parasite tissues was compared with the location of typical markers of the nervous system (serotonin (5HT) and FMRFamide) and a marker of microtubules (αtubulin). Prostaglandin E2 was revealed in the cells that are immunoreactive to αtubulin and are situated in the cortical parenchyma outside the central nervous sys tem (CNS). It is supposed that prostaglandin E2 is produced by the frontal glands and is carried out onto the tegument surface through specialized ducts. Immunoreaction to GABA was revealed in the central and peripheral nervous systems. GABAergic neurosomes, the neurites of which form a net on the surface of mus cle layers and in the subtegument, were revealed in the cerebral ganglion and main nerve cords. The morpho logical characteristics for the identification of serotoninergic neurons in the CNS were described."
Invertebrate Biology, 1996
The nervous system of the adult pike-tapeworm Triaenophorus nodulosus was studied to identify nerve cells and fibers immunoreactive to serotonin (5-HT) and RFamide (RF) on whole-mount preparations and frozen sections. Neurons immunoreactive to 5-HT were seen solely in the central nervous system, while those immunoreactive to RF occurred in the peripheral nervous system as well as in the central nervous system. In the scolex, both types of nerve fibers were found. While the gonads were not innervated by either fiber type, the reproductive tract showed RF-immunoreactive nerves. On the ultrastructural level, five types of neurons and three types of release sites and a neuromuscular junction could be distinguished. Levels of 5-HT, measured spectrofluorimetrically, were found to be lower in the tapeworm than in the tissues where it resides in its host, indicating a possibility that the parasite absorbs this bioamine from its environment.
Parasites & Vectors
Background: In Europe, the tapeworm Dibothriocephalus latus (syn. Diphyllobothrium latum) is a well-known etiological agent of human diphyllobothriosis, which spreads by the consumption of raw fish flesh infected by plerocercoids (tapeworm's larval stage). However, the process of parasite establishment in both intermediate and definitive hosts is poorly understood. This study was targeted mainly on the scolex (anterior part) of the plerocercoid of this species, which facilitates penetration of the parasite in intermediate paratenic fish hosts, and subsequently its attachment to the intestine of the definitive host. Methods: Plerocercoids were isolated from the musculature of European perch (Perca fluviatilis) caught in Italian alpine lakes. Parasites were examined using confocal microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Immunofluorescence tagging was held on whole mount larvae. Results: The organisation of the central and peripheral nervous system was captured in D. latus plerocercoids, including the ultrastructure of the nerve cells possessing large dense neurosecretory granules. Two types of nerve fibres run from the body surface toward the nerve plexus located in the parenchyma on each side of bothria. One type of these fibres was found to be serotoninergic and possessed large subtegumental nerve cell bodies. A well-developed gland apparatus, found throughout the plerocercoid parenchyma, produced heterogeneous granules with lucent core packed in a dense layer. Three different types of microtriches occurred on the scolex and body surface of plerocercoids of D. latus: (i) uncinate spinitriches; (ii) coniform spinitriches; and (iii) capilliform filitriches. Non-ciliated sensory receptors were observed between the distal cytoplasm of the tegument and the underlying musculature. Conclusions: Confocal laser scanning microscopy and electron microscopy (SEM and TEM) showed the detailed microanatomy of the nervous system in the scolex of plerocercoids, and also several differences in the larval stages compared with adult D. latus. These features, i.e. well-developed glandular system and massive hook-shaped uncinate spinitriches, are thus probably required for plerocercoids inhabiting fish hosts and also for their post-infection attachment in the human intestine.
Invertebrate Neuroscience, 1995
The nervous system (NS) of Dugesia tigrina has been studied by immunocytochemical double-staining, using the authentic flatworm neuropeptide, neuropeptide F (NPF), and serotonin (5-HT) on cryosections. This technique provides a precise morphological (descriptive) account of the NS. The results show that the central nervous system is shaped like a horseshoe. The brain is cornposed of two lateral lobes connected by three commissures, one antero-dorsal in front of the cerebral eyes and two, more ventral, behind the eyes. The pair of main nerve cords extend from the lateral lobes of the brain to the tail end of the worm. Cross sections reveal a very close contact between lateral branches from the main cords and the submuscular plexus. Thin cord-like lateral nerves are formed by longitudinal plexal fibres. No dorsal cords were observed. The patterns of immunoreactivity to NPF and 5-HT differ from each other in several respects. In the walls of gut diverticula only NPF immunoreactive (IR) cells and fibres were observed. Only NPF-immunoreactive cells occur in the parenchyma along dorso-ventral nerve fibres connecting the dorsal and ventral parts of the submuscular plexus. The number of 5-HT-immunoreactive cells associated with the main nerve cords (MCs) is greater than that of the NPF-immunoreactive cells, and the spongy structure of the MCs is more apparent f611owing immunostaining for 5-HT. Thin 5-HT-immunoreactive fibres were observed in the subepithelial plexus, penetrating the basal lamina and innervating a rhabdite-free ventro-lateral sensory area along the body periphery. The correspondence between MCs in the lower flatworms (Catenulida and Macrostomida) and the Seriata (Tricladida and Proseriata) confirms the status of the MCs in flatworms as the most important and stable neuronal characteristic, and constitutes support for the hypothesized common origin of the MCs in flatworms.