Nikishin V.B. 2010. [Structure and differentiation of tissues of cysticercoids. 2. Differentiation of the exocyst in typical diplocyst of Aploparaksis bulbocirrus (Cestoda: Hymenolepididae)] // Invertebrate Zoology. Vol.6 (for 2009). No.2: 129–145 [in Russian, with English summary].

Institute of the Biological Problems of the North, Portovaya Str. 18, 685000 Magadan, Russia, e-mail:

KEY WORDS: cysticercoid, diplocyst, ultrastructure, first invagination, scolexogenesis, tail appendix, exocyst.

ABSTRACT: The fine structure of tail appendix of the typical dyplocyst Aploparaksis bulbocirrus Deblock et Rausch, 1968 since first invagination up to stage of mature cysticercoid has been investigated. In composition of exocyst elements of epithelial and muscle tissues are defined and, besides, few low-differentiated cells of peculiar organization (“dark cells”) are found. Elements of the connective tissue are not revealed. The exocyst histogenesis is characterized by differences in tegument construction of its outer and inner surfaces, destructive changes of tegument after invagination of scolex, low-differential level of myocytes. The obtained data support the idea of protective and trophic functions of exocysts.

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