Cellular Plasticity of Nervous System of Helminthes at the Ultrastructural Level

A.I. Golubev^*, L.V. Malutina^**, M.M. Salnikova^***, Ya.I. Zabotin^****

Kazan Federal University, Kazan, 420008 Russia

E-mail: ^*anatolii.golubev_1937@mail.ru, ^**Ludmila.Malutina06@gmail.com, ^***m_salnikova@mail.ru, ^****yaroslav_zabotin@rambler.ru

Received May 30, 2017

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Abstract

Radical restructuring of the organism caused by the endoparasitic way of life largely influences the organization of the nervous system as the main mediator in relations with the environment, in particular with the internal environment of the host. Based on the original data on the fine structure of the nervous system of 18 species of helminthes from the phyla Plathelminthes, Nematoda, Acanthocephala, and Annelida, the idea of some plastic possibilities of nerve and neuroglial cells of worms, which, in our opinion, reflect their parasitic way of life, has been formulated. Particular attention has been paid to the structural plasticity of neurons of free-living and endoparasitic ecomorphs of the same species of oligochaetes, the ultrastructural differences of scolex and proglottid nerve cells of cestodes in the light of the strobilar theory, and the evolutionary role of the number of hosts in the life cycle of helminthes in the formation of the ultrastructure of their neurons.

Keywords: helminthes, plasticity, neurons, neuroglia, ultrastructure

Figure Captions

Fig. 1. Structural variations of the Nissl body in neurons of the nerve cord ganglias of the strobile of the cestode Dipylidium caninum. N – nucleus. Scale: 0.5 ?m.

Fig. 2. The structural scheme of scolex neuron of the procercoid of Pelichnibothrium speciosum. The arrows show plasmalemma invaginations and “lamellated corpuscles”. A region of the “lamellated corpuscle” is shown on the right side. Scale: 0.5 ?m.

Fig. 3. A neuron region of the nematode Oswaldocruzia biolata. N – neuron nucleus. The arrows show the plasmalemma. Scale: 0.5 ?m.

Fig. 4. A neuron region from the brain of the tapeworm Digramma interrupta. N – neuron nucleus. The arrows show plasmalemma invaginations. Scale: 0.5 ?m.

Fig. 5. Extracellular canals (ECC) in the neurogliar cell from the ganglia clusters of the ventral nerve cord of the European medicinal leech (Hirudo medicinalis). М – mitochondria, RG – cytoplasmic reservoirs in the neurogliar cell. Scale: 0.5 ?m.

Fig. 6. A region of the neurogliar cell of Hirudo medicinalis. M – mitochondria, RG – cytoplasmic reservoirs in the neurogliar cell, CPB – cytoplasmic bubbles. The arrow shows the area where a cytoplasmic bubble can possibly develop. Scale: 0.5 ?m.

Fig. 7. The scheme showing the arrangement of membrane-bound reservoirs in the cytoplasm of the neurogliar cell within the ganglia clusters of the ventral nerve cord of Hirudo medicinalis. М – mitochondria, RG – cytoplasmic reservoirs in the neurogliar cell.

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For citation: Golubev A.I., Malutina L.V., Salnikova M.M., Zabotin Ya.I. Cellular plasticity of nervous system of helminthes at the ultrastructural level. Uchenye Zapiski Kazanskogo Universiteta. Seriya Estestvennye Nauki, 2017, vol. 159, no. 3, pp. 409–420. (In Russian)

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