Organized Filaments in the adhesive system of Macrostomum tuba Graff, 1882 (Platyhelminthes, Macrostomida)

Publication Type:Journal Article
Year of Publication:2006
Authors:Silveira, Aragão
Journal:Brazilian Journal of Morphological Science
Keywords:Morphology Macrostomum

The adhesive organs or "duo-gland adhesive organs" of platyhelminths are formed by a specialized epithelial cell and extensions of two gland cells. These organs are used for temporary fixation of the organism to surfaces in aquatic habitats. The mechanisms involved in adhesion to and release from a given surface depend on secretions produced by the glands; less is known about the involvement of cytoplasmic filaments in the anchoring cell itself. In this study, we examined the structure of the adhesive organs present in the tail plate of Macrostomum tuba Graff, 1882 (Platyhelminthes, Macrostomida), a freshwater, free-living flatworm. Scanning and transmission electron microscopy allowed elucidation of the three-dimensional organization of the adhesive system, especially of the microvilli that formed the outer collar (or papilla), which was endowed with a fibrous core. Electrical stimulation caused the flatworms to extend their papillae above the ciliated surface. The use of tannin- and diamine-containing fixatives showed that the filamentous array contained tonofilaments and actin filaments. Tonofilaments concentrate in the axis of each microvillus; actin filaments, about 7-8 nm thick, spread out towards the periphery. Scanning images demonstrated the finger-like shape of the papillae, about 7-8 μm high, with a terminal opening. Microvilli followed a straight course along the surface.


Macrostomum tuba

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