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Helminthic infections of reptiles habiting in the territory of Armenia are examined. Seven species of helminths new for reptiles from Armenia are registered: Parapharyngodon skrjabini, Oswaldocruzia goezei, Neoxysomatium sp., Telorchis assula, Nematotaenia tarentolae, Mesocestoides lineatus and Spirometra erinacei europea. Descriptions and pictures of them are given.
Ultrastructural aspects of fertilization were studied in three cestode species: one proteocephalid with biflagellate spermatozoa, Proteocephalus longicollis, and two cyclophyllideans with uniflagellate spermatozoa, Inermicapsifer madagascariensis (Anoplocephalidae) and Mesocestoides lineatus (Mesocestoididae). Fertilization in all three species occurs in the oviduct lumen or in the fertilization canal proximal to the ootype, where the formation of the embryonic capsule precludes sperm contact with the oocyte. Cortical granules are not present in the oocytes of any of the three species. Spermatozoa coil spirally around the oocytes and syngamy occurs by lateral fusion of oocyte and sperm plasma membranes. In the ootype one (Proteocephalus and Inermicapsifer) or two (Mesocestoides) vitellocytes associate with the fertilized oocyte, forming a membranous capsule which encloses both cell types. In this stage, spirally coiled sperm flagella adhere partly to the external oocyte surfaces, and partially penetrate into the perinuclear cytoplasm. Usually, several loops of the spermatozoon occur within the oocyte cytoplasm. The electron-dense sperm nucleus within the oocyte cytoplasm becomes progressively electron lucent after penetration. Simultaneously with chromatin decondensation, the elongate sperm nucleus changes shape, forming a spherical male pronucleus, which attains the size of the female pronucleus. Cleavage begins immediately after pronuclear fusion.
Eggs within paruterine capsules of gravid proglottids of Distoichometra bufonis were examined by light and transmission electron microscopy. The embryonic capsule was membranous, but was immediately underlain by a non-uniform subcapsular lamina that was an intracellular component of the outer embryonic envelope. The subcapsular lamina was thick and semi-rigid on anterior and posterior poles, but thin and membranous laterally, giving the entire egg a laterally oblong shape. In contrast, the embryophore was spherical and uniform in thickness. The paruterine capsule walls were derived from layers of flattened processes of medullary parenchyma cells lined internally with a layer of uterine epithelium. All these layers extended inward to form parenchyma-uterine partitions segregating each egg into an individual chamber. The uterine epithelium was very thin, syncytial, and contained numerous vesicles. Little uterine secretory product occurred in the uterine lumen or on the outer surface of the embryonic capsule. Except for the unique subcapsular lamina, most features of the eggs and paruterine capsule resembled those of other nematotaeniid species. The paruterine capsule wall was similar to that of Mesocestoides lineatus, a species whose paruterine organ lacks parenchyma-uterine partitions.
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