Year-end Sale % OFF 
Abstract
This paper is part of a series investigating the muscular architecture of various “Polychaeta”, aiming to ascertain the presence of circular muscles in the body wall, which have recently been thought to be lacking more often than hitherto known. The F-actin muscular subset of Dorvillea kastjani was labelled with phalloidin and the architecture three-dimensionally reconstructed by means of confocal laser scanning microscopy. Three pairs of longitudinal, two transverse and numerous radial muscles ensure shape and flexibility of the prostomium. Mobility of the sub-biramous parapodia and their chaetae is achieved by seven different muscle types. The body wall contains transverse and bracing muscles and in total five longitudinal muscle strands: two dorsolateral, two ventral and one ventromedial. Numerous transverse fibres extend from the dorsal side peripherally and ventrally and become concentrated into six or seven pairs of bundles per segment on the ventral side. They terminate before reaching the midline, leaving a gap of only a few micrometres between them. Within the intersegmental furrows these fibres form complete rings in a supralongitudinal postion. Thus, true circular fibres exist in D. kastjani but are weakly developed.
Highlights
Presence of an outer layer of circular muscle fibres and an inner layer of longitudinal fibres, corresponding to an oligochaete-like arrangement of the body wall musculature, is generally considered to represent the ground pattern of the muscle system in Annelida
In contrast to this opinion previous histological and TEM studies (e.g. Mettam, 1967, 1971; Storch, 1968; Hermans, 1969; Tzetlin, 1987; Ivanov and Tzetlin, 1997; Tzetlin et al, 2002a) as well as recent cLSM investigations (Tzetlin et al, 2002b; Filippova et al, 2004; Müller and Worsaae, 2004) demonstrated that circular fibres are missing in an increasing number of polychaete species
The prostomium of Dorvillea kastjani is penetrated by three pairs of more or less longitudinally oriented muscles that attach at five sites
Summary
Presence of an outer layer of circular muscle fibres and an inner layer of longitudinal fibres, corresponding to an oligochaete-like arrangement of the body wall musculature, is generally considered to represent the ground pattern of the muscle system in Annelida Mettam (1976, 1971) pointed out that transverse muscle elements belonging to the parapodial muscle complex might have erroneously been interpreted as circular fibres. This contradictory information necessitates reinvestigation and complementation of present data as well as the examination of more samples in order to answer more general questions, e.g. how the muscles of the annelidan stem species were organized. Such broad-scale studies can be carried out by phalloidin-labelling and confocal laser scanning microscopic analysis, a combination that has already proved valuable in other invertebrate taxa with small specimens (e.g. Müller, 1999; Möllers and Müller, 2001; Tzetlin et al, 2002b; Müller and SchmidtRhaesa, 2002; Müller et al, 2004; Müller and Sterrer, 2004)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
