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  • 1
    Electronic Resource
    Electronic Resource
    The nervous system of Tricladida. II. Neuroanatomy ofDugesia tigrina (Paludicola, Dugesiidae): An immunocytochemical study (1995)
    Springer
    Invertebrate neuroscience 1 (1995), S. 133-143 
    Details
    ISSN: 1439-1104
    Keywords: immunocytochemistry ; nervous system ; Tricladida ; neuropeptide F (NPF) ; 5-HT ; orthogon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nervous system (NS) ofDugesia 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 composed 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 following 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02331911
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  • 2
    Electronic Resource
    Electronic Resource
    The organization of the nervous system in Plathelminthes. The neuropeptide F-immunoreactive pattern in Catenulida, Macrostomida, Proseriata (1995)
    Springer
    Zoomorphology 115 (1995), S. 83-97 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of the nervous system of Archilopsis unipunctata Promonotus schultzei and Paramonotus hamatus (Monocelididae, Proseriata) and Stenostomum leucops (Catenulida) and Microstomum lineare (Macrostomida) was studied by immunocytochemistry, using antibodies to the authentic flatworm neuropeptide F (NPF) (Moniezia expansa). The organization of the nervous system of the Monocelididae was compared to that of the nervous system of Bothriomolus balticus (Otoplanidae), a previously studied species of another family of the Proseriata. The results show that the main nerve cords (MCs), independent of lateral or ventral position in the Monocelididae and the Otoplanidae, correspond to each other. The study also confirms the status of the lateral cords as main cords (MCs) in S. leucops and M. lineare. Common for MCs in the members of the investigated taxa are the following features: MCs consist of many fibres, originate from the brain and are adjoined to 5-HT-positive neurons. In Monocelididae and Otoplanidae, the MCs additionally have the same type of contact to the pharyngeal nervous system. Also common for both proseriate families is the organization of the two lateral nerve cords, with weaker connections to the brain, and the pair of dorsal cords running above the brain. The organization of the minor cords differs. The Monocelididae have a pair of thin ventral cords forming a mirror image of the dorsal pair. Furthermore, an unpaired ventral medial cord connecting medial commissural cells was observed in P. schultzei. Marginal nerve cords, observed in Otoplanidae, are absent in Monocelididae. All minor nerve cords are closely connected to the peripheral nerve plexus. The postulated trends of condensation of plexal fibres to cords and/or the flexibility of the peripheral nerve plexus are discussed. In addition, the immunoreactivity (IR) pattern of NPF was compared to the IR patterns of the neuropeptide RFamide and the indoleamine, 5-HT (serotonin). Significant differences between the distribution of IR to NPF and to 5-HT occur. 5-HT-IR dominates in the submuscular and subepidermal plexuses. In the stomatogastric plexus of M. lineare, only peptidergic IR is observed in the intestinal nerve net. The distribution of NPF-IR in fibres and cells of the intestinal wall in M. lineare indicates a regulatory function for this peptide in the gut, while a relationship with ciliary and muscular locomotion is suggested for the 5-HT-IR occurring in the subepidermal and submuscular nerve, plexuses. In M. lineare, the study revealed an NPF- and RFamide-positive cell pair, marking the finished development of new zooids. This finding indicates that constancy of these cells is maintained in this asexually reproducing and regenerating species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403257
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  • 3
    Electronic Resource
    Electronic Resource
    The nervous system of Bothriomolus balticus (Proseriata) —a contribution to the knowledge of the orthogon in the Plathelminthes (1993)
    Springer
    Zoomorphology 113 (1993), S. 113-127 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nervous system (NS) of Bothriomolus balticus (Proseriata) was studied by the immunocytochemical (ICC) method with antisera to RFamide, SALMFamide and serotonin and with the histochemical GAIF method. The use of the ICC technique provided a much more precise morphological account of the nervous system than had previously been possible. The obtained data are discussed in connection with the comparative morphology of the nerve cords of the Plathelminthes. A similar position does not grant direct correspondence between nerve cords in the taxon Seriata. Marginal cords had probably an independent origin in the Monocelididae and Otoplanidae. The ventral (main) cords of B. balticus seem to correspond to the lateral (main) cords of the Monocelididae. It can be hypothesized that both: (1) a shift of the main cords accompanied by formation of new cords from the plexus and fusion of other cords and (2) a redistribution of nerve processes and perikarya between the cords, take part in the evolution of cords in the Plathelminthes. The first hypothesis seems to explain the difference in the position of main cords in proseriates, though, the second hypothesis might dominate, for example, in the Neorhabdocoela and the Neodermata. The correctness of the evolutionary analysis of the nerve cords in plathelminths can only be provided by neurons or neuron groups marking these structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403089
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  • 4
    Electronic Resource
    Electronic Resource
    Growth factors in asexually reproducing catenulida and macrostomida (Plathelminthes)? (1992)
    Springer
    Zoomorphology 112 (1992), S. 155-165 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The occurrence and localization of immuno-reactivity (IR) to epidermal growth factor receptor (EGF-r), epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), revealed by the present study, indicate growth-factor-like substances in the asexually reproducing flatworms,Stenostomum leucops andMicrostomum lineare. IR to all three antibodies occurs in the nervous system. Differences in the number of positive cells and intensity of IR during asexual development of new individuals were observed. By confocal scanning laser microscopy, immunopositive growth cones of nerve fibres were seen in developing zooids, and weakly or unstained perikarya were observed in close contact with the positive nerve fibres. Antibodies to the growth factors EGF-r, EGF and bFGF as well as to the neuroactive substances 5-HT and RF-amide had a negative influence on the growth and asexual reproduction of culturedS. leucops. No significant differences in the influence of antibodies to growth factors and antibodies to the neuroactive substances were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01633106
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  • 5
    Electronic Resource
    Electronic Resource
    The release sites and targets of nerve cells immunoreactive to RFamide — an ultrastructural study ofMicrostomum lineare andDiphyllobothrium dendriticum (Plathelminthes) (1990)
    Springer
    Zoomorphology 109 (1990), S. 303-308 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A detailed study of the ultrastructure and RFamide immunoreactivity (RF-IR) in the flatwormsMicrostomum lineare andDiphyllobothrium dendriticum has been made with the immunogold technique. The present ultrastructural study confirms the localization of RF-IR cells observed by light microscopic immunocytochemistry. The RF-IR is demonstrated in small, electron-dense vesicles in neuronal cell bodies and processes. RF-IR is not detected in the rough endoplasmatic reticulum or the Golgi system of the nerve cells. The targets of RF positive fibres are nerve fibres, muscles and glands. Gold labelling occurs in classic synapses, which points to a role in neurotransmission. RF-IR is also observed in nerve terminals lacking the characteristics of synapses. These release sites occur close to muscle fibres in the intestine and body musculature ofM. lineare. Thus, an additional, paracrine action of the neuropeptide is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00803570
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  • 6
    Electronic Resource
    Electronic Resource
    Neuronal signal substances in asexual multiplication and development in flatworms (1996)
    Springer
    Cellular and molecular neurobiology 16 (1996), S. 591-616 
    Details
    ISSN: 1573-6830
    Keywords: flatworms ; asexual multiplication ; development ; neuronal signal substances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The phenomenon of asexual multiplication is rare in the animal kingdom. It occurs, however, in all main flatworm taxa. Flatworms are characterized by an extensive versatility, ranging from the different types of asexual multiplication to the different orthogonal plans for the nervous system. The role of the nervous system in the asexual multiplication taking place in flatworms is pointed out and discussed. 2. Immunocytochemical studies of the changes in the flatworm neuroanatomy show that the nervous system, particularly the main never cords, has a central role during asexual development. 3. Antibodies to different neuronal substances yield different immunoreactivity patterns and develop according to different time schedules. Serotoninergic nervous elements seem to have a leading role. 4. Substances produced by the nervous system influence fissioning and subsequent regeneration in free-living flatworms in the following ways. (a) A function as a wound hormone has been suggested for the neuropeptide RF-amide. (b) Mitogenic effects have been shown for several biogenic amines and neuropeptides. (c) Inhibitory roles are suggested for somatostatin and melatonin in connection with cell proliferation respective fissioning. 5. Growth factors have been observed both in free-living and parasitic flatworms. 6. Cells reactive to antibodies against epidermal growth factor increase in number in parallel with increases in mitotic activity in the gull tapeworm and occur in regions with high mitotic activity. A correlation between these two phenomena is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02152059
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  • 7
    Electronic Resource
    Electronic Resource
    No news on the flatworm front! Nitric oxide synthase in parasitic and free-living flatworms (1998)
    Springer
    Hydrobiologia 383 (1998), S. 161-166 
    Details
    ISSN: 1573-5117
    Keywords: Nitric oxide ; NADPH diaphorase ; Diphyllobothrium ; Girardia ; Hymenolepis ; Planaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The free radical nitric oxide (NO) has emerged as a simple and unique signalling molecule that can serve as neurotransmitter, paracrine substance or hormone. NO is a gas, formed by various neuronal cells, both centrally and peripherally. NO regulates cyclic GMP synthesis. The production of NO can be detected using the NADPH diaphorase (NADPH-d) histochemical stain for nitric oxide synthase (NOS). NOS was detected in two parasitic flatworms, Diphyllobothrium dendriticum and Hymenolepis diminuta, and two free-living flatworms, Planaria torva and Girardia tigrina. The staining for NOS was very strong in the nervous system of both parasitic worms. The main nerve cords, the transverse ring commmissures, nerves in association with the musculature, especially the cirrus musculature and sensory nerve endings showed NADPH-d staining. The NADPH-d staining in the free-living flatworms was much weaker. Still NOS activity was found in the neuropile of the brain and in association with the pharynx musculature. The demonstration of NOS in flatworms, indicates that NO is an old signal molecule in evolutionary terms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003472419317
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  • 8
    Electronic Resource
    Electronic Resource
    Organization of the orthogon – main and minor nerve cords (1998)
    Springer
    Hydrobiologia 383 (1998), S. 175-182 
    Details
    ISSN: 1573-5117
    Keywords: Orthogon ; flatworm ; central nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The central nervous system of flatworms has been regarded as comprised of the bilobed brain, the longitudinal cords and the connecting transverse commissures forming a so called orthogon. The peripheral nervous system comprises the submuscular and subepidermal plexuses. As a confusion in the terminology of the longitudinal nerve cords has prevailed, two concepts have been introduced, the main nerve cords (MCs) and the minor cords. The MCs have been defined as the pair of longitudinal nerve cords that (1) start with strongest roots in the brain, (2) consist of wide fibre bundles and (3) are associated with more neurons (particularly amninergic marker neurons) than the other cords. Longitudinal nerve cords in other positions are thinner and have less pronounced contact with the brain. They have collectively been named minor cords. Support for the special status of the MCs has been obtained from studies of the neuroanatomy of Catenulida, Macrostomida, Proseriata, Tricladida and Lecithoepitheliata and of parasitic flatworms. Using the above mentioned criteria for the MCs and the results of recent studies, we present the following hypothese: The MCs in all flatworms correspond to each other and have a common origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003478030220
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  • 9
    Electronic Resource
    Electronic Resource
    The nervous system of Tricladida. I. Neuroanatomy ofProcerodes littoralis (Maricola, Procerodidae): An immunocytochemical study (1995)
    Springer
    Invertebrate neuroscience 1 (1995), S. 113-122 
    Details
    ISSN: 1439-1104
    Keywords: immunocytochemistry ; nervous system ; Tricladida ; neuropeptide F (NPF) ; orthogon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of the nervous system ofProcerodes littoralis (Tricladida, Maricola, Procerodidae) was studied by immunocytochemistry, using antibodies to authentic flatworm neuropeptide F (NPF) (Moniezia expansa). Compared to earlier investigations of the neuroanatomy of tricladid flatworms, the pattern of NPF immunoreactivity inProcerodes littoralis reveals differences in the following respects: 1. Shape and structure of the brain. 2. Number and composition of longitudinal nerve cords. 3. Shape of branches of, and transverse connections between, main ventral nerve cords. 4. Composition of the pharyngeal nervous system. The rich innervation by NPF immunoreactive (IR) fibres and cells of the subepithelial muscle layer, the pharynx musculature and the musculature of the male copulatory apparatus indicates a neurotransmitter or neuromodulatory influence on muscular activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02331909
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  • 10
    Electronic Resource
    Electronic Resource
    GABA in the nervous system of the planarian Polycelis nigra (1995)
    Springer
    Hydrobiologia 305 (1995), S. 285-289 
    Details
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in vertebrates and it has a similar inhibitory role in several invertebrate taxa. The transmitters serotonin, octopamine, catecholamines and histamine are present in flatworms while evidence for GABA is still lacking. Therefore, we have studied the occurrence of GABA-like immunoreactivity (IR) in the planarian nervous system. Specimens of Polycelis nigra were fixed in 4% 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide with 2% paraformaldehyde. The GABA-antiserum was raised in rabbits against GABA conjugated to keyhole limpet hemocyanin. Preabsorption with GABA-ovalbumin conjugate abolished all IR. The results were further confirmed with an monoclonal antibody and high pressure liquid chromatography (HPLC). In P. nigra GABA-like IR was seen as long, often varicose, sparsely distributed fibers in the ventral longitudinal nerve cords. IR was also located in a few cell somata in the brain and in the neuropil of the brain. The IR was restricted to the central nervous system and was absent in peripheral nerves and plexuses. The HPLC analysis supported the presence of GABA. Our results suggest that GABA is an interneuronal transmitter in P. nigra. The results also suggest a phylogenetically old origin of GABAergic neurotransmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036408
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