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The Structure and Origin of the Plasmodium of Rhopalura ophiocomae (Phylum Orthonectida)
Author(s) -
Kozloff Eugene N.
Publication year - 1994
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1994.tb01206.x
Subject(s) - coelom , biology , cytoplasm , peritoneum , anatomy , parasite hosting , plasmodium (life cycle) , matrix (chemical analysis) , microbiology and biotechnology , materials science , world wide web , computer science , composite material
Adult orthonectids develop from germinal cells within a cytoplasmic matrix called a plasmodium. This is generally assumed to be formed by the parasite. In the case of Rhopalura ophiocomae , which lives in the brittle star Amphipholis squamata , the plasmodia occupying the perivisceral coelom are closely associated with the walls of the genital bursae or the gut, and they are covered by peritoneum. They have been reported to contain scattered small nuclei distinct from those within germinal cells, embryos, and adults, but the results of the present study indicate that such nuclei probably do not exist. Furthermore, electron micrographs show that some plasmodia are in continuity with the cytoplasm of contractile cells that lie beneath the peritoneum of a genital bursa or the gut of the host. The matrix of a plasmodium of R. ophiocomae appears, therefore, to consist of cytoplasm of a contractile cell. It is proposed that after a contractile cell has been entered by an infective cell of the parasite, it hypertrophies, bulging progressively farther into the perivisceral coelom and lifting up the peritoneum, which remains in intimate contact with it.