Nikishin V.B. 2010. [Structure and differentiation of the tissues of cysticercoids. 3. Differentiation of the endocyst of typical diplocyst of Aploparaksis bulbocirrus (Cestoda: Aploparaksidae)] // Invertebrate Zoology. Vol.7. No.2: 159–176 [in Russian, with English summary].

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

KEY WORDS: cysticercoid, typical diplocyst, ultrastructure, development, first invagination, scolexogenesis, endocyst.

ABSTRACT: Fine structure of endocyst of the developing and young cysticercoid Aploparaksis bulbocirrus Deblock et Rausch, 1968, referring as “typical diplocyst” has been studied. It was shown that a cavity for invaginated scolex and neck, was formed de novo. During cystogenesis tegument, muscle elements, excretory system, inner boundary of endocyst and secretory cells, were differentiated. Muscular cells form both muscles and fibrous layers located between distal cytoplasm of tegument and cellular layer. Fibroblasts and nervous elements were not identified. Full formation of endocyst’s wall including formation of glycocalix layer, modification of microvilli and distal cytoplasm of tegument took place after invagination of scolex and neck into its cavity. The results confirm our consideration about endocyst as a defensive structure adapted to mechanical and chemical actions in the initial part of digestive tract of their definitive host.

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