Ref ID : 7588
Maria Mulisch, Wilhelm Barthlott, and Klaus Hausmann; [Struktur und Ultrastrucktur von Eufolliculina spec. Schwarmer und Sessiles Stadium]. Protistologica XVII(3):285-312, 1981
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The sessile form of Eufolliculina produces a motile, mouthless swarmer by transverse fission. After some time, the swamer settles on the substrate, produces a new lorica, and changes into the sessile form. In this article the ultrastructure of the sessile form and of the swarmer is described. Particular attention is paid to the organisation of the cortex of the two forms. The swarmer has only a short spiral of buccal membanelles at the apical pole of the cell, whereas the sessile form has two peristomial wings which each has a peripheral band of membranelles. Lying inside the row membranelles a row of solitary cilia may act as barrier to trap food during feeding. In the cytoplasm of the buccal region are long vesicles filled with an electron-dense material which are guided to the cytostome by microtubular ribbons. The vesicles fuse with the cytostome to provide membrane for the developing food vacuoles. At the same time they secrete their contents, possibly digestive enzymes, into the food vacuole. These vesicles are produced continually, even in the mouthless swarmer. The swarmer and the sessile form are highly contractile. As in other contractile heterotrichs, the cortex of Eufolliculina contains myonemes and km-fibres. The general positions of these structures are the same in both stages, but whereas the swarmer has one myoneme for each set of km-fibres the sessile form has two. This supplementary myoneme may explain the greater contarctility of the sessile stage. The arrangement of the cortical cilia in the apical part of the Eufolliculina differs from the rest of the cortex in both, swarmer and sessile form. In the apical region of the cell, the km-fibres are derived from the unciliated basal bodies of each pair, but they come from the ciliated basal bodies in the rest of the cortex.