Pospekhova N.A. 2009. [Rostellar sac gland in Cloacotaenia megalops (Cestoda: Hymenolepididae)] // Invertebrate Zoology. Vol.6. No.1: 33–46 [in Russian, with English summary].

Institute of the Biological Problems of the North of FEB RAS, Portovaya St.,18, Magadan, 685000, Russia. E-mail: posna@ibpn.ru

KEY WORDS: Cestoda, tegument, rostellar gland, ultrastructure.

ABSTRACT: The morphology of the rostellar sac gland in juvenile (from a thin intestine of pintail) and adult (attached to a cloaca wall) cestodes Cloacotaenia megalops (Nitzsch in Creplin, 1829) is studied for the first time. Fixation of the adult parasites to a cloaca wall is carried out by means of powerful suckers; the apical pit, a homologue of rostellum, is a place for secret release from gland. It represents the group of specialized tegumentary cytons, borrowing most part of rostellar sac’s volume and limited by its muscular wall. Alongside with typical discoid bodies, the glandular cytones of juvenile cestodes produce large (up to 1,2 microns), round, dense granules. Glands of adult, attached to a cloaca wall, cestodes, produce erithroid granules with diameter about 350 nm. Prominent feature of rostellar sac gland at this stage is presence of intranuclear inclusions: a stuff with fibrillar material. The glandular secret in juvenile and adult cestodes is released via the distal cytoplasm of apical pit into their lumen by apocrine means. Possible functional significance of intranuclear inclusions and a secret of rostellar sac gland secretion at different stages of cestode life cycle are discussed.

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