The uptake of macromolecules by endocytosis could not be demonstrated in the tegument of Cyclophyllidea by Lumsden et al. (1970), whereas in Pseudophyllidea, pinocytotic activity of the tegument was reported by Hopkins et al. (1978) and Threadgold and Hopkins (1981). The latter authors described the uptake of electron-dense markers (lanthanum nitrate, horseradish peroxidase and ruthenium red) by the tegument ofSchistocephalus solidus andLigula intestinalis. A reinvestigation with ferritin, horseradish peroxidase, and ruthenium red in plerocercoids and adults ofS. solidus revealed that no pinocytotic activity occurs in this species in vitro. Moreover, it could be shown that the ruthenium red method used by the authors mentioned above is unsuitable for the demonstration of pinocytosis, as it leads to the production of electron-dense artefacts in the tegument that are not related to endocytotic uptake of the tracer. Additionally, ruthenium red induced toxic effects in the tegument. Morphological examination of electron lucent vesicles, often called pinosomes, established no evidence relating them to pinocytosis. The whole topic of endocytosis in cestodes remains controversial.
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Conradt, U., Peters, W. Investigations on the occurrence of pinocytosis in the tegument ofSchistocephalus solidus . Parasitol Res 75, 630–635 (1989). https://doi.org/10.1007/BF00930961
- Toxic Effect