The article analyzes own and published data concerning muscle elements present in various parts of the trematode reproductive system. The data on the presence of serotonergic and peptidergic (FMRFamidergic) nerve elements evidence the innervation of the trematode reproductive system departments by these neurotransmitters. The available literature information was supplemented by results of the study carried out on Prodistomum alaskense, a representative of the family Lepocreadiidae, an intestinal parasite of deep-sea fish (Zaprora silenus and Aptocyclus ventricosus). The localization of serotonergic and FMRFamidergic nerve structures was determined by immunocytochemistry. The musculature was stained using TRITC (tetramethylrhodamine-isothiocyanate) conjugated phalloidin. The slides were examined using a fluorescent microscope and a confocal laser scanning microscope. An analysis of the data and information in the literature suggest that the muscular system of the reproductive system is well developed in trematodes of various taxonomic groups and represented by circular, longitudinal, and, in some cases, by diagonal muscle fibers. The musculature of the trematode reproductive system is innervated by serotonergic and peptidergic (FMRFamidergic) neurons and their fibers which may be involved in regulating the contractile activity in various parts of the trematode reproductive system.

Our studies were aimed at analyzing biodiversity of ecto- and endoparasites of sheep, cattle, rabbits, domestic birds and dogs in the lowland zone of the Republic, with semidesert climate and height of 850 m above the sea level. This is one of the warm regions of the Republic. The studies performed have established moderate and high degree of animal infection with parasites. We identified 33 parasite species, mostly helminths (15 species), including 10 species of nematodes (Trichocephalus ovis, Nematodirus spathiger, Haemonchus contortus, Chabertia ovina, Dictyocaulus filaria, Muellerius capillaris, Protostrongylus spp., Passalurus ambiqus, Ascaridia galli, Heterakis gallinarum), 4 species of trematodes (Fasciola hepatica, F. gigantica, Dicrocoelium dendriticum, Paramphistomum cervi), 1 species of cestodes (Moniezia expansa), 9 protozoan species (Piroplasma bigeminum, Babesia ovis, Eimeria perforans, E. magna, E. irresidua, E. tenella, E. acervulina), 7 species of ticks, 1 species of insects, and 1 species of leishmaniasis vector, the mosquitos from the genus Phlebotomus. We registered 5 species of freshwater molluscs (Lymnaea auricularia, L. stagnalis, L. ovata, L. truncatula, Planorbis planorbis), and 2 species of terrestrial molluscs (Helicella derbentina, Napaeopsis hohenackeri).

Monitoring studies were performed on biological diversity of parasite fauna in domesticated animals at the territory of the Joint Russian-Armenian Scientific Experimental Centre, within the piedmont zone of Armenia with moderate continental climate at 900-1200 m above the sea level. The study species were large and small ruminants, rabbits and hens. All the animals except sheep were kept indoors (stalls). We found 3 trematode species, 4 cestode species and 5 nematode species based on seasonal coproovoscopic and larvoscopic examinations, as well as an incomplete helminthological dissections of 5 sheep. The infection of sheep and cattle with hematophagous parasites was also detected and the infection of hens and rabbits with helminths and protozoa was found. Oribatid mites Scheloribates sp. were isolated from the studied soil samples. We also found and studied land and freshwater molluscs, intermediate hosts of a number of important parasite species for the infection. The land molluscs were found to have naturally-acquired invasions with larval forms of Protostrongylidae and Dicrocoeliidae. In total, we found 20 helminth species, 5 ixodid ticks, 1 oribatid mite and 7 protozoa, and vectors: 2 species of freshwater molluscs and 1 species of land molluscs.

Trematodes of the Bucephalidae family differ from all other trematodes by the number of morphological characteristics including the structure of their attachment organ as well as the digestive and reproductive systems. In this study, the muscular system and nerve components containing serotonin and neuropeptide FMRFamid were investigated in Rhipidocotyle campanula (Bucephalidae family) from the intestine of the pike. Using immunocytochemical methods and confocal scanning laser microscopy (CSLM), data on the presence and distribution of neurotransmitters serotonin as well as the neuropeptide FMRFamide in the central and peripheral nervous system of Rh. campanula were obtained. When studying the relationship of nerve structures containing the studied neurotransmitters, muscle fibers of the muscle elements of the parasite were stained using the phalloidin associated with the fluorophore. Information on the organization of the muscular system, attachment organ, digestive and reproductive systems is given. The data obtained suggest that serotonergic and FMRF-amidergic nerve structures are involved in the regulation of the function of the attachment organ, as well as the digestive and terminal departments of the eproductive system of Rh. campanula. A comparative analysis of the obtained results and related data available in the literature for other trematodes was carried out.

A haemoparasitic disease, babesiasis was studied in dogs, brought to the Laura Dog Club, located in Yerevan city. Work in this direction was conducted from midApril till the end of November 2019. 25 working and hunting dogs, and 5 stray dogs were examined. Peripheral blood smears were prepared from animals with severe clinical symptoms of haemoparasitic disease to differentiate babesiasis. After fixing and staining, smear microscopy was performed under an immersion microscope system. Studies of blood smears showed that Babesia canis was found in red blood cells of examined dogs. The carriers of Babesia canis are Ixodid tics of the species Rhipicephalus sanguineus, Rh. bursa, Dermacentor marginatus, the latter species was found in a dog brought from the territory of the forest-mountain zone of Armenia. The species of Ixodid ticks, and the degree of tick infestation, were determined. It turned out that the dogs were mainly infected by the species Rh. sanguineus. It was found that the intensity of infection by Ixodid ticks in dogs in summer was 100%, and the intensity of infection was 10–20 ticks in each animal. Almost the same picture of ticking was observed in autumn.