A confocal microscopical study of the musculature of adult Schistosoma mansoni

Using the filamentous actin marker, FITC-conjugated phalloidin, the major m uscle systems of adult male and female schistosomes have been examined. The body wall musculature comprises an outer sheath of circular fibres, within which there is a compact layer of short, spindle-shaped longitudinal fibre s and a lattice-like arrangement of inner diagonal fibres. Within the Oral sucker and acetabulum 3 fibre types, circular, radial and longitudinal can be distinguished. The wall of the oesophagus is lilted by a grid-like array of circular and longitudinal fibres, whereas the walls of the intestinal c aeca contain only comparably broad circular fibres. Within the female repro ductive system, only circular fibres are present in the oviduct, vitelline duct and uterus. In contrast, the wall of the ootype displays closely arran ged circular and longitudinal muscle fibers. Antisera to previously identif ied myoactive compounds (serotonin [5-hydroxytryptamine, 5-HT], neuropeptid e F [Moniezia expansa] and GYIRFamide [Bdelloura candida, Dugesia tigrina]) were used as neuronal markers in a preliminary study of the spatial inter- relationships of specific nerve fibres and various muscle systems. Serotoni nergic fibres innervate both suckers and also constitute a subtegumental ne rve net. In males they provide innervation to the dorso-ventral muscle fibr es of the gynaecophoric canal, and in females they innervate the circular a nd longitudinal muscle fibres of the ootype. Neuropeptide F and the FMRFami de-related peptide, GYIRFamide are both localized within nerve plexuses ass ociated with the dorso-ventral fibres of the gynaecophoric canal, and are e vident in the innervation of the ventral and oral sucker.