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Muscle Systems (muscle + system)
Selected AbstractsThe fine structure of the muscle system in the female of the orthonectid Intoshia variabili (Orthonectida)ACTA ZOOLOGICA, Issue 2 2003George S. Slyusarev Abstract The contractile system of the female Intoshia variabili (Orthonectida) consists of smooth muscles. The attachment of the longitudinal muscle fibres at the anterior and the posterior tips of the body is rather peculiar, accomplished by means of elongated terminal muscle cells piercing through several ciliated cells. In the last ciliated cell, the muscle cell invaginates the ciliated cell basal membrane almost up to the ciliated cell surface. Here, around the protrusion terminus, there is an electron-dense zone in contact with the cilia rootlets. [source] Major muscle systems in the larval caenogastropod, Ilyanassa obsoleta, display different patterns of developmentJOURNAL OF MORPHOLOGY, Issue 10 2009Carol C.E. Evans Abstract This study describes the anatomical and developmental aspects of muscular development from the early embryo to competent larval stage in the gastropod Ilyanassa obsoleta. Staining of F-actin revealed differential spatial and temporal patterns of several muscles. In particular, two major muscles, the larval retractor and pedal retractor muscles originate independently and display distinct developmental patterns similar to observations in other gastropod species. Additionally, together with the larval retractor muscle, the accessory larval muscle developed in the embryo at the trochophore stage. Therefore, both these muscles develop prior to ontogenetic torsion. The pedal retractor muscle marked the most abundant growth in the mid veliger stage. Also during the middle stage, the metapodial retractor muscle and opercular retractor muscle grew concurrently with development of the foot. We show evidence that juvenile muscles, such as the buccal mass muscle and siphon muscle develop initially during the late veliger stage. Collectively, these findings substantiate that larval myogenesis involves a complex sequence of events that appear evolutionary conserved within the gastropods, and set the stage for future studies using this model species to address issues concerning the evolution and eventual fates of larval musculature in molluscs. J. Morphol., 2009. © 2009 Wiley-Liss, Inc. [source] Myogenesis in Aplysia californica (Cooper, 1863) (Mollusca, Gastropoda, Opisthobranchia) with special focus on muscular remodeling during metamorphosisJOURNAL OF MORPHOLOGY, Issue 7 2008Tim Wollesen Abstract To date only few comparative approaches tried to reconstruct the ontogeny of the musculature in invertebrates. This may be due to the difficulties involved in reconstructing three dimensionally arranged muscle systems by means of classical histological techniques combined with light or transmission electron microscopy. Within the scope of the present study we investigated the myogenesis of premetamorphic, metamorphic, and juvenile developmental stages of the anaspidean opisthobranch Aplysia californica using fluorescence F-actin-labeling in conjunction with modern confocal laser scanning microscopy. We categorized muscles with respect to their differentiation and degeneration and found three true larval muscles that differentiate during the embryonic and veliger phase and degenerate during or slightly after metamorphosis. These are the larval retractor, the accessory larval retractor, and the metapodial retractor muscle. While the pedal retractor muscle, some transversal mantle fibers and major portions of the cephalopedal musculature are continued and elaborated during juvenile and adult life, the buccal musculature and the anterior retractor muscle constitute juvenile/adult muscles which differentiate during or after metamorphosis. The metapodial retractor muscle has never been reported for any other gastropod taxon. Our findings indicate that the late veliger larva of A. californica shares some common traits with veligers of other gastropods, such as a larval retractor muscle. However, the postmetamorphic stages exhibit only few congruencies with other gastropod taxa investigated to date, which is probably due to common larval but different adult life styles within gastropods. Accordingly, this study provides further evidence for morphological plasticity in gastropod myogenesis and stresses the importance of ontogenetic approaches to understand adult conditions and life history patterns. J. Morphol., 2008. © 2007 Wiley-Liss, Inc. [source] Molluscan muscle systems in development and evolution,JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2000G. Haszprunar The evolutionary history of the various molluscan muscle systems reflects drastic modifications and reductions as well as true innovations. No less than eight main and independent muscle systems of the Mollusca are described and, based on the current understanding of molluscan phylogeny, their evolutionary histories are outlined.New data on the myogenesis of the Polyplacophora by means of fluorescence-staining and image analysis by confocal laser scanning microscopy show that the pre-oral region recapitulates a ,worm-grid', and that the dorso-ventral musculature passes a stage of multiple seriality as found in adult Solenogastres. Old and new data on bivalves and recent studies on primitive gastropods provide clear evidence that the larval musculature of both groups (and thus possibly of all conchiferans) is entirely independent from the adult condition. The growth of shell-inserted muscles always necessitates substantial renewal of myocytes which is still poorly understood. Although very promising for phylogenetic purposes, the understanding of the developmental genetics of the various molluscan muscle systems is still in its infancy. [source] Preparation, morphology and pH sensitivity of hybrid hydrolyzed polyacrylonitirile- blend -gelatin hydrogel fibersPOLYMER INTERNATIONAL, Issue 9 2008Liwei Yu Abstract BACKGROUND: Polyacrylonitrile (PAN) artificial muscles have attracted considerable attention for their fast responses. This research work is based on the preparation of novel pH-sensitive hydrogel fibers derived from hydrolyzed PAN and gelatin by wet spinning and chemical modification. RESULTS: Through characterization of the fiber dynamic and static pH-sensitive behavior, pH response times were found to improve greatly with increasing gelatin content. At a weight ratio of 3 to 7 (PAN:gelatin), the best response times were obtained at 0.59 s for elongation and 1.14 s for contraction. Study of the chemical structures of hydrolyzed PAN and gelatin, as well as the surface morphology of the hydrogel fibers, indicated that the mechanism of formation of hydrogel fibers is closely interconnected with their pH-sensitive behavior. From the standpoint of the mechanism we also found that the addition of urea gave rise to hydrogel fibers with a controllable morphology, influenced by the pH-sensitive behavior. CONCLUSION: The hydrogel system reported here is simple in preparation, but quite complex in chemical structure. The strong response of the fibers to pH provides some idea on the development of new artificial muscle systems. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||