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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6587

Magda de Eguileor, Giulio Lanzavecchia, Roberto Valvassori, and Jr. Plinio Lanzavecchia; Unusual model of lumbriculids' helical muscles: comparison with body wall muscles in other microdriles. Hydrobiologia 155:135-144, 1987

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Longitudinal body wall muscles of lumbriculids are characterized by unique peculiarities; they are ribbon-shaped, with regularly destributed Z-elements and sarcotubules crossing the fibres from one side to another. These act as a sequence of pivots for mechanical and functional control during contraction. Myosin filaments are equally ribbon-shaped, and in the XZ plane they appear sigmoid. All these characteristics can be deduced from a comparison between theoretical computerized images and corresponding electron micrographs. The muscles of lumbriculids are only apparently similar to those of enchytraeids and tubificids, and are completely different from the muscles of haplotaxids and branchiobdellids. A comparison between body wall muscles of these microdriles suggests the opportunity of using the muscle organization and ultrastructure as a taxonomic character.