scholarly journals FILAMENT LENGTHS IN STRIATED MUSCLE

1963 ◽  
Vol 19 (2) ◽  
pp. 369-390 ◽  
Author(s):  
Sally G. Page ◽  
H. E. Huxley
Keyword(s):  
Electron Microscope ◽  
Striated Muscle ◽  
Filament Length

Filament lengths in resting and excited frog muscles have been measured in the electron microscope, and investigations made of the changes in length that are found under different conditions, to distinguish between those changes which arise during preparation and the actual differences in the living muscles. It is concluded that all the measured differences in filament length are caused by the preparative procedures in ways that can be simply accounted for, and that the filament lengths are the same in both resting and excited muscles at all sarcomere lengths greater than 2.1 µ, viz., A filaments, 1.6 µ; I filaments, 2.05 µ. The fine periodicity visible along the I filaments also has been measured in frog, toad, and rabbit muscles and found to be 406 A.

scholarly journals Changes in thick filament length in Limulus striated muscle.

1977 ◽  
Vol 75 (2) ◽  
pp. 366-380 ◽  
Author(s):  
M M Dewey ◽  
B Walcott ◽  
D E Colflesh ◽  
H Terry ◽  
R J Levine
Keyword(s):  
Horseshoe Crab ◽  
Striated Muscle ◽  
Thick Filament ◽  
Filament Length ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Wide Range ◽  
The Difference

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 microns) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 microns) (P less than 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 microns) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 microns) and the difference is significant (P less than 0.001). Thin filaments are 2.4 microns in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle.

scholarly journals POLARIZED LIGHT OBSERVATIONS ON STRIATED MUSCLE CONTRACTION IN A MITE

1967 ◽  
Vol 32 (1) ◽  
pp. 169-179 ◽  
Author(s):  
John F. Aronson
Keyword(s):  
Light Microscopy ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
Polarized Light ◽  
Rate Of Change ◽  
Filament Length ◽  
Relative Movement ◽  
Significant Difference ◽  
Average Slope ◽  
Region Length

Contraction of individual sarcomeres within the living mite Tarsonemus sp. was observed by polarized light microscopy. In unflattened animals the usual range of contraction was such that the minimum sarcomere length approximated the length of the A region, and the maximum sarcomere length was about twice the length of the A region. The central sarcomeres of the dorsal metapodosomal muscles were observed in detail. The A band length increased slightly with increasing sarcomere length since the regression of I region length on sarcomere length had an average slope of 0.91. When the A band length in a sarcomere which was shortening was compared with the length when the same sarcomere lengthened, no significant difference was seen. The A band of each sarcomere seemed to act as a not too rigid limit to further shortening; this agreed with the reversible shortening of a muscle in which the A band had been experimentally shortened. An H region was visible at long sarcomere lengths and was not visible at short sarcomere lengths, even when the muscle was actively shortening. The rate of change of H region length with sarcomere length suggested that I filament length may increase as sarcomere length increases. Despite this effect and the small increase in A length with sarcomere length, the results are considered to be consistent with a model in which shortening occurs by the relative movement of A and I filaments, with little or no change in length of either set of filaments. Sarcomere shortening was clearly associated with an increase in the retardation of the A region.

The structure of actin filaments and the origin of the axial periodicity in the I -substance of vertebrate striated muscle

1964 ◽  
Vol 160 (981) ◽  
pp. 449-460 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscope ◽  
Actin Filaments ◽  
Striated Muscle ◽  
Rabbit Skeletal Muscle ◽  
Contractile Apparatus ◽  
Detailed Structure

Certain advances due mainly to H. E. Huxley (see Huxley 1961, 1963) have made it possible to use the electron microscope to study the detailed structure of the filaments in the contractile apparatus. The results of our work on actin filaments have already been published (Hanson & Lowy 1962, 1963). We shall now examine some of the consequences of these findings, including certain unsolved problems which they raise. Actin in the polymerized form ( F -actin) has been prepared from rabbit skeletal muscle by the usual methods and examined in negatively stained preparations in the electron microscope (Hanson & Lowy 1963). It has been found that solutions of F -actin are, in fact, suspensions of filaments. These consist of globular subunits arranged in a characteristic helical manner (figure 15).

scholarly journals ULTRASTRUCTURE OF THE RESTING AND CONTRACTED STRIATED MUSCLE FIBER AT DIFFERENT DEGREES OF STRETCH

1961 ◽  
Vol 11 (1) ◽  
pp. 95-117 ◽  
Author(s):  
F. Carlsen ◽  
G. G. Knappeis ◽  
F. Buchthal
Keyword(s):  
Isometric Contraction ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
Fiber Diameter ◽  
Filament Length ◽  
Filament Diameter ◽  
Cent Increase ◽  
Passive Stretch ◽  
Tetanic Tension ◽  
Striated Muscle Fiber

Passive stretch, isometric contraction, and shortening were studied in electron micrographs of striated, non-glycerinated frog muscle fibers. The artifacts due to the different steps of preparation were evaluated by comparing sarcomere length and fiber diameter before, during, and after fixation and after sectioning. Tension and length were recorded in the resting and contracted fiber before and during fixation. The I filaments could be traced to enter the A band between the A filaments on both sides of the I band, creating a zone of overlap which decreased linearly with stretch and increased with shortening. This is consistent with a sliding filament model. The decrease in the length of the A and I filaments during isometric contraction and the finding that fibers stretched to a sarcomere length of 3.7 µ still developed 30 per cent of the maximum tetanic tension could not be explained in terms of the sliding filament model. Shortening of the sarcomeres near the myotendinous junctions which still have overlap could account for only one-sixth of this tension, indicating that even those sarcomeres stretched to such a degree that there is a gap between A and I filaments are activated during isometric contraction (increase in stiffness). Shortening, too, was associated with changes in filament length. The diameter of A filaments remained unaltered with stretch and with isometric contraction. Shortening of 50 per cent was associated with a 13 per cent increase in A filament diameter. The area occupied by the fibrils and by the interfibrillar space increased with shortening, indicating a 20 per cent reduction in the volume of the fibrils when shortening amounted to 40 per cent.

The electron microscope as a diagnostic tool for skeletal muscle disease

1986 ◽  
Vol 44 ◽  
pp. 372-373
Author(s):  
J. E. Bilbao ◽  
R. A. Turner ◽  
R. T. King ◽  
J. C. Stinson
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscope ◽  
Diagnostic Tool ◽  
Microscopic Examination ◽  
Striated Muscle ◽  
Electron Microscopic Examination ◽  
Muscle Disease ◽  
Electron Microscopic ◽  
Pathologic Physiology ◽  
Reaction Patterns

Time and experience has proven that striated muscle has only a limited number of reaction patterns. However, the electron microscopic examination has given information about the ultrastructural reaction of muscle fibers and about the pathologic physiology of diseased muscle. Although specific abnormalities are not useful when present individually. When present in a combination they may be diagnostic.

Sign in / Sign up

Export Citation Format

Share Document