Proliferations of the sarcoplasmic reticulum and the T system in denervated muscle fibers

1972 ◽  
Vol 11 (1) ◽  
pp. 147-160 ◽  
Author(s):  
Z. Gori
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Denervated Muscle ◽  
T System

scholarly journals ULTRASTRUCTURE AND ADENOSINE TRIPHOSPHATASE ACTIVITY OF RED AND WHITE MUSCLE FIBERS OF THE CAUDAL REGION OF A FISH, SALMO GAIRDNERI

1972 ◽  
Vol 55 (1) ◽  
pp. 42-57 ◽  
Author(s):  
Asish C. Nag
Keyword(s):  
Electron Microscopy ◽  
Sarcoplasmic Reticulum ◽  
Adenosine Triphosphatase ◽  
White Muscle ◽  
Muscle Fibers ◽  
Salmo Gairdneri ◽  
Fiber Types ◽  
Surface Areas ◽  
Biochemical Studies ◽  
T System

Electron microscopy, together with quantitation using a tracing device linked to a digital computer, reveals that the red and white muscle fibers of Salmo gairdneri differ in diameter, organization of myofibrils, dimensions of myofilaments, volumes and surface areas of T system and sarcoplasmic reticulum, morphology of mitochondria, and content of mitochondria, lipid, and glycogen. Biochemical studies show that the ATPase activity of white fibers is three times that of the red fibers. Actomyosin content of red fibers is higher than that of the white fibers. The functional significance of these differences between two fiber types is discussed.

scholarly journals STEREOLOGICAL ANALYSIS OF MAMMALIAN SKELETAL MUSCLE

1974 ◽  
Vol 60 (3) ◽  
pp. 732-754 ◽  
Author(s):  
Brenda R. Eisenberg ◽  
Aileen M. Kuda ◽  
James B. Peter
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Muscle Fibers ◽  
Mammalian Skeletal Muscle ◽  
Fiber Volume ◽  
Spatial Gradients ◽  
Surface Areas ◽  
Orientation Anisotropy ◽  
Mitochondrial Volume ◽  
T System

A quantitative analysis of the volumes, surface areas, and dimensions of the ultrastructural components in the soleus muscle fibers of the guinea pig was made by using point counting methods of stereology. Muscle fibers have structural orientation (anisotropy) and have spatial gradients of the structures within the fiber; therefore the standard stereological methods were modified where necessary. The entire analysis was repeated at two section orientations to test the modifications and identical results obtained from both. The volume of lipid droplets was 0.20 ± 0.06% (mean ± standard error, n = 5 animals) and the nuclei volume was 0.86 ± 0.20% of the fiber volume. The total mitochondrial volume was 4.85 ± 0.66% of the fiber volume with about one-third being found in an annulus within 1 µm of the sarcolemma. The mitochondrial volume in the remaining core of the fiber was 3.6 ± 0.4%. The T system has a volume of 0.14 ± 0.01% and a surface area of 0.064 ± 0.005 µm2/µm3 of the fiber volume. The surface area of the sarcolemma is 0.116 ± 0.013 µm2/µm3 which is twice the T system surface area. The volume of the entire sarcoplasmic reticulum is 3.52 ± 0.33% and the surface area is 0.97 ± 0.09 µm2/µm3. The sarcoplasmic reticulum is composed of the terminal cisternae whose volume is 1.04 ± 0.19% and surface area is 0.24 ± 0.05 µm2/µm3. The tubules of the sarcoplasmic reticulum in the I band and A band have volumes of 1.97 ± 0.24% and 0.51 ± 0.08%, and the surface areas of the I and A band reticulum are 0.56 ± 0.07 µm2/µm3 and 0.16 ± 0.04 µm2/µm3, respectively. The Z line width, myofibril and fiber diameters were measured.

scholarly journals THE ORGANIZATION OF FLIGHT MUSCLE FIBERS IN THE ODONATA

1966 ◽  
Vol 28 (1) ◽  
pp. 109-126 ◽  
Author(s):  
David S. Smith
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Flight Muscle ◽  
Insect Flight ◽  
Muscle Fibers ◽  
Physiological Role ◽  
Morphological Evidence ◽  
Extracellular Milieu ◽  
Membrane Components ◽  
T System

The cytological organization of flight muscle fibers of Odonata has been investigated. These fibers, in representatives of the Zygoptera and Anisoptera, have been compared and found to be similar, except that, in the former, pairs of lamellar fibrils, rather than single fibrils, alternate with the mitochondria. In each instance, in these synchronous muscles, the actin filaments of the myofibrils are found to lie opposite to and midway between pairs of myosin filaments—a configuration previously reported in asynchronous flight muscle fibers. The disposition of the T system and sarcoplasmic reticulum membranes in glutaraldehyde-fixed anisopteran muscle is described in detail: the T system tubules are shown to be radially continuous across the fiber, and are derived as openmouthed invaginations from the surface cell-membrane. The detailed organization of the dyad junctions between these tubules and the adjoining cisternae of the sarcoplasmic reticulum is described. The accessibility of the T system interior to diffusion exchange with the general extracellular milieu has been investigated by studies on the penetration of ferritin into the fiber: molecules of this marker have been found to diffuse solely along the T system tubules, and their presence in the tubule extremities adjoining the centrally placed nuclei confirms the morphological evidence suggesting that these tubules provide open diffusion channels extending across the radius of the fiber. The possible physiological role of these membrane components and their distribution in synchronous muscles of insects and vertebrates and in asynchronous insect flight muscle are discussed.

Intracellular localization of markers within injected or cut frog muscle fibers

1979 ◽  
Vol 237 (1) ◽  
pp. C50-C55 ◽  
Author(s):  
B. R. Eisenberg ◽  
R. T. Mathias ◽  
A. Gilai
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Horseradish Peroxidase ◽  
Cross Section ◽  
Intracellular Localization ◽  
Muscle Fibers ◽  
Central Area ◽  
Molecular Probes ◽  
Frog Muscle ◽  
Pressure Injection ◽  
T System

Many experimental procedures require drastic alterations of muscle fibers, such as cutting the fiber or injecting molecular probes through microelectrodes. We report the ultrastructure of similarly altered muscle fibers and the intracellular distribution of injected horseradish peroxidase (HRP). Cut fibers appear structurally normal at distances greater than 500 microM from the cut end, however, the structure deteriorates nearer to the cut. HRP diffuses longitudinally about 2,000 micrometer from the cut end and the concentration is uniform over the fiber's cross section. If HRP is introduced intracellularly either by pressure injection or through a nick in the sarcolemma, it distributes in a C-shaped annulus extending approximately 2,000 micrometer longitudinally and 1–20 micrometer radially. The ultrastructure of injected or nicked fibers appears normal. The HRP freely entered the junctional gap between T-system and sarcoplasmic reticulum (SR) but was excluded from either structure. Occasionally, a light pillar could be seen between T-system and SR; the space of these pillars suggest they are the central area of the “feet” appearing light against the dark marker.

scholarly journals A COMPARATIVE STUDY ON THE FINE STRUCTURE OF THE BASALAR MUSCLE OF THE WING AND THE TIBIAL EXTENSOR MUSCLE OF THE LEG OF THE LEPIDOPTERAN ACHALARUS LYCIADES

1967 ◽  
Vol 33 (3) ◽  
pp. 531-542 ◽  
Author(s):  
J. F. Reger ◽  
D. P. Cooper
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Flight Muscle ◽  
Muscle Fibers ◽  
Extensor Muscle ◽  
Insect Muscle ◽  
Hexagonal Packing ◽  
Electron Microscopes ◽  
Fast Acting ◽  
Postural Muscles ◽  
T System

Basalar and tibial extensor muscle fibers of Achalarus lyciades were examined with light and electron microscopes. Basalar muscle fibers are 100–150 µ in diameter. T-system membranes and sarcoplasmic reticulum make triadic contacts midway between Z lines and the middle of each sarcomere. The sarcoplasmic reticulum is characterized by a transverse element situated among myofilaments halfway between Z lines in every sarcomere. The morphology of Z lines, hexagonal packing of thin and thick myofilaments, and thin/thick myofilament ratios are similar to those of fast-acting insect muscles. Tibial extensor muscle fibers are 50–100 µ in diameter. Except for a lack of the transverse element, the T system and sarcoplasmic reticulum are similar to those of basalar muscle. Wavy Z lines, lack of a hexagonal packing of myofilaments, and larger thin/thick myofilament ratios are similar to those of other postural muscles of insects. The morphology of basalar and tibial extensor muscle is compared to that of other insect muscle with known functions, and reference is made to the possible contribution of the transverse element of sarcoplasmic reticulum in basalar flight muscle to speed and synchrony in this muscle.

scholarly journals THE SARCOPLASMIC RETICULUM, THE T SYSTEM, AND THE MOTOR TERMINALS OF SLOW AND TWITCH MUSCLE FIBERS IN THE GARTER SNAKE

1965 ◽  
Vol 26 (2) ◽  
pp. 467-476 ◽  
Author(s):  
Arthur Hess
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Fibers ◽  
Postsynaptic Membrane ◽  
Slow Muscle ◽  
Garter Snake ◽  
Transverse Tubular System ◽  
Physiological Reaction ◽  
Slow Fiber ◽  
Tubular System ◽  
T System

Twitch and slow muscle fibers, identified morphologically in the garter snake, have been examined in the electron microscope. The transverse tubular system and the sarcoplasmic reticulum are separate entities distinct from each other. In twitch fibers, the tubular system and the dilated sacs of the sarcoplasmic reticulum form triads at the level of junction of A and I bands. In the slow fibers, the sarcoplasmic reticulum is severely depleted in amount and the transverse tubular system is completely absent. The junctional folds of the postsynaptic membrane of the muscle fiber under an "en grappe" ending of a slow fiber are not so frequent or regular in occurrence or so wide or so long as under the "en plaque" ending of a twitch fiber. Some physiological implications of these differences in fine structure of twitch and slow fibers are discussed. The absence of the transverse tubular system and reduction in amount of sarcoplasmic reticulum, along with the consequent disposition of the fibrils, the occurrence of multiple nerve terminals, and the degree of complexity of the post junctional folds of the sarcolemma appear to be the morphological basis for the physiological reaction of slow muscle fibers.

scholarly journals FINE STRUCTURE OF RAT INTRAFUSAL MUSCLE FIBERS

1971 ◽  
Vol 51 (1) ◽  
pp. 83-103 ◽  
Author(s):  
William K. Ovalle
Keyword(s):  
Muscle Fiber ◽  
Muscle Fibers ◽  
Muscle Spindles ◽  
Intrafusal Muscle ◽  
Dense Granules ◽  
Intrafusal Muscle Fibers ◽  
Sarcotubular System ◽  
Nuclear Chain ◽  
T System ◽  
Nuclear Bag

An ultrastructural comparison of the two types of intrafusal muscle fibers in muscle spindles of the rat was undertaken. Discrete myofibrils with abundant interfibrillar sarcoplasm and organelles characterize the nuclear chain muscle fiber, while a continuous myofibril-like bundle with sparse interfibrillar sarcoplasm distinguishes the nuclear bag muscle fiber. Nuclear chain fibers possess well-defined and typical M bands in the center of each sarcomere, while nuclear bag fibers contain ill-defined M bands composed of two parallel thin densities in the center of the pseudo-H zone of each sarcomere. Mitochondria of nuclear chain fibers are larger and more numerous than they are in nuclear bag fibers. Mitochondria of chain fibers, in addition, often contain conspicuous dense granules, and they are frequently intimately related to elements of the sarcoplasmic reticulum (SR). Striking differences are noted in the organization and degree of development of the sarcotubular system. Nuclear bag fibers contain a poorly developed SR and T system with only occasional junctional couplings (dyads and triads). Nuclear chain fibers, in contrast, possess an unusually well-developed SR and T system and a variety of multiple junctional couplings (dyads, triads, quatrads, pentads, septads). Greatly dilated SR cisternae are common features of nuclear chain fibers, often forming intimate associations with T tubules, mitochondria, and the sarcolemma. Such dilatations of the SR were not encountered in nuclear bag fibers. The functional significance of these structural findings is discussed.

Structure and innervation of the swim bladder musculature in the weakfish, Cynoscion regalis (Teleostei: Sciaenidae)

1982 ◽  
Vol 60 (8) ◽  
pp. 1955-1967 ◽  
Author(s):  
R. Dana Ono ◽  
Stuart G. Poss
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Fiber ◽  
Muscle Fibers ◽  
Postsynaptic Membrane ◽  
Motor Endplate ◽  
Central Core ◽  
Swim Bladder ◽  
Motor Endplates ◽  
Cynoscion Regalis

The striated swim bladder muscles of the weakfish Cynoscion regalis are deep red in color but cannot be classified histologically as having typical red fibers. The muscle fibers are homogeneous and average 29.6 ± 5.3 μm in diameter, one-fifth the diameter of the adjacent hypaxialis fibers. Each muscle fiber contains thin, ribbonlike myofibrils which are radially arranged around a central core of mitochondria, glycogen, and sarcoplasmic reticulum. Myofibrils are extremely regular in pattern. Triads occur at the Z line. Numerous mitochondria and muscle nuclei are located at the periphery of each muscle fiber. The muscle fibers are multiply innervated with motor endplates distributed along their entire lengths. Well-developed folding of the postsynaptic membrane, not previously reported in fishes, is present at the motor endplate.

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