scholarly journals STRUCTURE OF LIMULUS STRIATED MUSCLE

1973 ◽  
Vol 58 (3) ◽  
pp. 574-593 ◽  
Author(s):  
Maynard M. Dewey ◽  
Rhea J. C. Levine ◽  
David E. Colflesh
Keyword(s):  
Muscle Fiber ◽  
Conformational Changes ◽  
Cross Sections ◽  
Striated Muscle ◽  
Limulus Polyphemus ◽  
Thick Filaments ◽  
Apparent Decrease ◽  
Ventral Muscle ◽  
Striated Muscle Fiber

The musculature of the telson of Limulus polyphemus L. consists of three dorsal muscles: the medial and lateral telson levators and the telson abductor, and one large ventral muscle; the telson depressor, which has three major divisions: the dorsal, medioventral, and lateroventral heads. The telson muscles are composed of one type of striated muscle fiber, which has irregularly shaped myofibrils. The sarcomeres are long, with discrete A and I and discontinuous Z bands. M lines are not present. H zones can be identified easily, only in thick (1.0 µm) longitudinal sections or thin cross sections. In lengthened fibers, the Z bands are irregular and the A bands appear very long due to misalignment of constituent thick filaments. As the sarcomeres shorten, the Z lines straighten somewhat and the thick filaments become more aligned within the A band, leading to apparent decrease in A band length. Further A band shortening, seen at sarcomere lengths below 7.4 µm may be a function of conformational changes of the thick filaments, possibly brought about by alterations in the ordering of their paramyosin cores.

The site and state of myosin in intestinal smooth muscle

1973 ◽  
Vol 265 (867) ◽  
pp. 219-222 ◽  
Keyword(s):  
Smooth Muscle ◽  
Cross Sections ◽  
Striated Muscle ◽  
Mechanical Tension ◽  
Constant Length ◽  
Substantial Modification ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Resting Muscle ◽  
Longitudinal Layer

The longitudinal layer of the guinea-pig ileum represents a highly advantageous specimen for the study of vertebrate smooth muscle structure. In this muscle we regularly observed thick filaments, consisting presumably of myosin, in longitudinal as well as in cross-sections, if the samples were fixed at constant length, i.e. standing under mechanical tension. Thick filaments were regularly present also in muscles relaxed by atropine. On the other hand, thick filaments were absent in many cases in slack muscles in K+ contracture. As a consequence, we regard myosin filaments as regular constituents of smooth muscle, independently of the functional state. Their absence in electronmicrographs taken from slack muscles seems an artefact due to processing. We observed the same artefact in bee-wing muscle, i.e. in a striated muscle, too. This fact indicates the importance of mechanical tension and polymer crystallization in the survival of myosin filaments. On the basis of a recent work of Ladik, Biczó and Garamvölgyi we discuss how tension may be exerted on the myosin filaments of the resting muscle. Anyway, the sliding model seems valid also for vertebrate smooth muscle, without any substantial modification.

Mechanism of Supercontraction in a Striated Muscle Fiber

Science ◽  
1963 ◽  
Vol 141 (3582) ◽  
pp. 712-713 ◽  
Author(s):  
G. Hoyle ◽  
J. H. McAlear
Keyword(s):  
Muscle Fiber ◽  
Striated Muscle ◽  
Striated Muscle Fiber

scholarly journals Striated muscle fiber apoptosis after experimental tendon lesion in a rat model

2012 ◽  
Vol 221 (4) ◽  
pp. 358-363 ◽  
Author(s):  
Carla Palumbo ◽  
Claudio Rovesta ◽  
Marzia Ferretti
Keyword(s):  
Muscle Fiber ◽  
Rat Model ◽  
Striated Muscle ◽  
Tendon Lesion ◽  
Striated Muscle Fiber
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