This study aims to describe the ultrastructure of coiled musculature fibers component of Gyrodactylus gasterostei and its role in this parasite transmission. The present work employs transmission electron microscopy to analyze G. gasterostei musculature, revealing the presence of myosin and actin bands in the underlying epithelium, typical arrangement of the skeletal muscle. This study unravels for the first time the existence of a coil muscle component in which it seems to be responsible for the remarkable flexibility of the musculature of Gyrodactylus and the efficiency of its transmission method to reach a nearby fish host. The elasticity of the musculature described in this study may be comparable with the other specialized elastic musculature within the animal kingdom (i.e., lizards tongue). The clarification of the basic biology of these monogenean parasites and its musculature biochemical systems hold the promise of possible novel muscle targets for a new generation of antiparasitic drugs.
Keywords: Actin; coil; elastic; muscle; myosin; transmission.