title: Limulus striated muscle provides an unusual model for muscle contraction.
abstract: Although nearly two decades have passed since de Villafranca (1961) described A-band shortening, controversy persists. Here we will review the data which has been amassed since de Villafranca 's description. We will conclude that A-bands and thick filaments shorten during sarcomere shortening in Limulus striated muscle. Further we will suggest that two machines operate in this muscle: a tension generating sliding filament system and a tension generating thick filament shortening system. Also we will suggest a mechanism of force generation of the filament shortening system and provide evidence for a cycling bridge mechanism for this muscle.
mesh_terms: D000818:Animals; D003599:Cytoskeleton / Q000502:physiology; D005583:Fourier Analysis; D005990:Glycerol / Q000494:pharmacology; D006737:Horseshoe Crabs; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure*; D009210:Myofibrils / Q000502:physiology / Q000648:ultrastructure*; D012518:Sarcomeres / Q000502:physiology / Q000648:ultrastructure
chemical_list: D005990:Glycerol