Article

The Structure of the Ovarian Ball and Oogenesis in Moniliformis dubius (Acanthocephala)

Journal of morphology (Impact Factor: 1.71). 04/1976;

ABSTRACT Seven to nine days after infection of the definitive host (rat) by cystacanths, the genital primordium of the female acanthocephalan is transformed from a fragmented mass of cells into discrete ovarian balls. This is accomplished by envelopment of free germinal cells by somatic tissue which originates from the ligament sac primordium. Germinal cell nuclei then undergo repeated mitoses until about 21 days of development, with concurrent formation of oogonial syncytia which occupy the interior of the ovarian balls. Oocytes derived from these oogonia move to the periphery of the germinal syncytia for differentiation, growth, fertilization, shell formation and release from the ovarian ball. After oogonial proliferation ceases, continued growth of the ovarian ball apparently results from increase in size of already present cells.

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    ABSTRACT: The data on the fine structure and formation of embryonic envelopes in acanthocephalans have been reviewed. Three forms of eggshell organization were recognized according to the ultrastructure of the embryonic envelopes which corresponded to the taxonomic status of acanthocephalans at the class level. The third embryonic envelope is the most variable; its particular structure can be considered a morphological adaptation of the eggs to environmental conditions. Actual formation proceeds as the subsequent formation of embryonic envelopes and intervening space start from the outer envelope. Details of the "fertilization membrane" histogenesis are discussed.
    Izvestiia Akademii nauk. Seriia biologicheskaia / Rossiiskaia akademiia nauk 01/2001;

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