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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7523

Igor B. Raikov; [Ultrastructure de Cytoplasme et des Nematocystes du Cilie Remanella multinucleata Kahl (Gymnostomata, Loxodidae) Existence de Nematocystes chez les Cilies]. Protistologica XIV(4):413-432, 1978

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Somatic kineties of the right body side of Remanella multinucleata consist of paired kinetosomes, of which both are ciliated. The anterior kinetosome of a pair bears a short transverse ribbon of six or seven microtubules, while the posterior one gives rise to a short double kinetodesmal filament and to a long postciliary ribbon of microtubules. Postciliary ribbons are stacked to form a postciliodesma on the right side of a kinety, while a thin myoneme passes along its left side. The left body side is not ciliated except of two marginal kineties consisting of single kinetosomes. The somatic ciliature of Remanella is thus very similar to that of Loxodes. The pellicle consists of the plasma membrane, underlain by a thin epiplasmic layer and a sheet of microtubules. The cytoplasm contains a highly developed smooth endoplasmic reticulum in form of a general lacunary system; stacked smooth membranes also occur, especially near the left body side. There are two layers of calcareous spiculi near the right body side, the outer consisting of transverse spiculi and the inner of longitudinal ones. The granular endoplasmic reticulum consists of isolated flattened vesicles, some of which are basal elements of Golgi bodies. The latter are abundant near the ciliated body side. True nematocysts exist in R. multinucleata (first case among the ciliates). These are subpellicular, confined to the left body side, and occur mainly near the body ends. The nematocysts ate pyriform membrane-limited, about 2 µm in length. They consist of an amorphous capsule and a coiled internal filament. At the apical end of the nematocysts, the capsule is covered with a fibrous cap, peirced by an axial channel. This is occluded by a plug a the level of the capsule. The filament begins at the inner side of the plug and makes about two coils in a single longitudinal plane inside the capsule. Outside this plane, the capsule is strengthened from the inside by deposition of a periodically structured material. The wall of the filament is thick and concentrically striated; it bears a ring-formed dense structure at its free end.