scholarly journals CHANGES IN THE SARCOPLASMIC RETICULUM AND TRANSVERSE TUBULAR SYSTEM OF FAST AND SLOW SKELETAL MUSCLES OF THE MOUSE DURING POSTNATAL DEVELOPMENT

1971 ◽  
Vol 51 (2) ◽  
pp. 369-383 ◽  
Author(s):  
A. R. Luff ◽  
H. L. Atwood
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Postnatal Development ◽  
Surface Area ◽  
Fiber Surface ◽  
Fiber Volume ◽  
Transverse Tubular System ◽  
Tubular System ◽  
Slow Twitch Muscle ◽  
T Tubules ◽  
Relative Change

The sarcoplasmic reticulum (SR) and transverse tubular system (TTS) of a fast-twitch muscle (extensor digitorum longus-EDL) and a slow-twitch muscle (soleus-SOL) of the mouse were examined during postnatal development. Muscles of animals newborn to 60 days old were fixed in glutaraldehyde and osmium tetroxide and examined with an electron microscope. At birth the few T tubules were often oriented longitudinally, but at the age of 10 days most of them had a transverse orientation. In the EDL, the estimated volume of the TTS increased from 0.08% at birth to 0.4% in the adult; corresponding values for the SOL were 0.04% at birth and 0.22% in the adult. A similar relative change was observed in surface area of the TTS during development. Calculated on the basis of a 30 µm diameter fiber, the surface area of the TTS in the EDL increased from 0.60 cm2 TTS/cm2 fiber surface in the newborn to 3.1 cm2/cm2 in the adult, compared with 0.15 cm2/cm2 at birth to 1.80 cm2/cm2 in the adult for the SOL. The SR in the newborn muscles occurred as a loose network of tubules that developed rapidly within the subsequent 20 days, especially at the I band level. The volume of the SR increased in the EDL from 1.1% of fiber volume at birth to 5.5% in the adult. In the SOL the change was from 1.7% to 2.9%. The SOL approached the adult values more rapidly than the EDL, although the EDL had more SR and T tubules. Fibers of both EDL and SOL muscles showed variation in Z line thickness, mitochondrial content, and diameter, but over-all differences between the two muscles in amount of SR and TTS were significant. It is considered that the differing amounts of SR and TTS are closely related to the differing speeds of contraction that have been demonstrated for these two muscles.

scholarly journals THE SARCOPLASMIC RETICULUM AND TRANSVERSE TUBULES OF THE FROG'S SARTORIUS

1965 ◽  
Vol 25 (3) ◽  
pp. 209-231 ◽  
Author(s):  
Lee D. Peachey
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Osmium Tetroxide ◽  
Fiber Surface ◽  
Sartorius Muscle ◽  
Fiber Volume ◽  
Transverse Tubules ◽  
Contraction Coupling ◽  
Terminal Cisternae

The sarcoplasmic reticulum of the frog's sartorius muscle was examined by electron microscopy following sequential fixation in glutaraldehyde and osmium tetroxide and embedding in Epon. The earlier results of Porter and Palade on Ambystoma muscle were confirmed in the sartorius. In addition, the transverse tubules were observed to be continuous across the width of the fiber, a set of flat intermediate cisternae was seen to connect the terminal cisternae to the longitudinal tubules in the A band, and the continuous reticulum collar at the center of the A band was found to be perforated by circular and elongated pores (the fenestrated collar). The transverse tubules have a volume about 0.3 per cent of the fiber volume, and a surface area about 7 times the outer cylindrical surface area for a fiber 100 µ in diameter. The terminal cisternae, the intermediate cisternae, and the longitudinal tubules together with the fenestrated collar each have a volume of 4 to 5 per cent of the fiber volume and a surface area 40 to 50 times the outer surface area of a fiber 100 µ in diameter. Some evidence for continuity of the transverse tubules with the fiber surface is presented, but this is thought to be not so convincing as evidence presented by others. The results are discussed in terms of a possible mechanism for a role of the transverse tubules and sarcoplasmic reticulum in excitation-contraction coupling, as suggested by their morphology and a variety of physiological studies. In this scheme, the transverse tubules are thought to be electrically coupled to the terminal cisternae, so that depolarization of the fiber surface spreads inward along the transverse tubules and to the terminal cisternae, initiating the release of a contraction-activating substance.

scholarly journals Sizes of components in frog skeletal muscle measured by methods of stereology.

1975 ◽  
Vol 66 (1) ◽  
pp. 31-45 ◽  
Author(s):  
B A Mobley ◽  
B R Eisenberg
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Volume Ratio ◽  
Sartorius Muscle ◽  
Morphological Parameters ◽  
Frog Skeletal Muscle ◽  
Fiber Volume ◽  
Transverse Tubules ◽  
Terminal Cisternae

Stereological techniques of point and intersection counting were used to measure morphological parameters from light and electron micrographs of frog skeletal muscle. Results for sartorius muscle are as follows: myofibrils comprise 83% of fiber volume; their surface to volume ratio is 3.8 mum-1. Mitochondria comprise 1.6% of fiber volume. Transverse tubules comprise 0.32% of fiber volume, and their surface area per volume of fiber is 0.22 mum-1. Terminal cisternae of the sarcoplasmic reticulum comprise 4.1% of fiber volume; their surface area per volume of fiber is 0.54 mum-1. Longitudinal sarcoplasmic reticullum comprises 5.0% of fiber volume, and its surface area per volume of fiber is 1.48 mum-1. Longitudinal bridges between terminal cisternae on either side of a Z disk were observed infrequently; they make up only 0.035% of fiber volume and their surface area per volume of fiber is 0.009 mum-1. T-SR junction occurs over 67% of the surface of transverse tubules and over 27% of the surface of terminal cisternae. The surface to volume ratio of the caveolae is 48 mum-1; caveolae may increase the sarcolemmal surface area by 47%. Essentially the same results were obtained from semitendinosus fibers.

scholarly journals Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle.

1988 ◽  
Vol 91 (6) ◽  
pp. 799-815 ◽  
Author(s):  
K G Beam ◽  
C M Knudson
Keyword(s):  
Skeletal Muscle ◽  
Postnatal Development ◽  
Fiber Surface ◽  
Calcium Currents ◽  
Charge Movement ◽  
Mammalian Skeletal Muscle ◽  
Similar Time ◽  
Indirect Measure ◽  
Membrane Area ◽  
Transverse Tubular System

Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle.

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.

The Ultrastructure of the White Striated Myotomal Muscle of the Cod, Gadus morhua

1967 ◽  
Vol 24 (12) ◽  
pp. 2549-2553 ◽  
Author(s):  
C. M. Bishop ◽  
P. H. Odense
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Cross Section ◽  
Actin Filaments ◽  
Gadus Morhua ◽  
Striated Muscle ◽  
Fish Muscle ◽  
Transverse Tubular System ◽  
Tubular System ◽  
Myotomal Muscle

The structure of the white skeletal muscle of the cod (Gadus morhua) is described. The peripheral fibrils are ribbon-like and rectangular in cross section with the long axis normal to the sarcolemma. The inner fibrils are mainly polygonal in cross section. Most of the mitochondria and nuclei are peripheral to the fibrils and next to the sarcolemma. The arrangement of the contractile proteins is typical for striated muscle, and the sarcoplasmic reticulum and transverse tubular system are similar to those in other white skeletal fish muscle. A distinct N-band is apparent with indications of branching and reorientation of the actin filaments. Mitochondria are often closely associated with the Z line.

scholarly journals The Mode of Transverse Spread of Contraction Initiated by Local Activation in Single Frog Muscle Fibers

1967 ◽  
Vol 50 (9) ◽  
pp. 2167-2176 ◽  
Author(s):  
Haruo Sugi ◽  
Rikuo Ochi
Keyword(s):  
Muscle Fibers ◽  
Fiber Surface ◽  
Ringer Solution ◽  
Frog Muscle ◽  
Transverse Tubular System ◽  
Local Activation ◽  
Current Pulses ◽  
Negative Current ◽  
Tubular System

Isolated single frog muscle fibers were locally activated by applying negative current pulses to a pipette whose tip was in contact with the fiber surface. In contrast to the graded inward spread of contraction initiated by a moderate depolarization, the contraction in response to a strong negative current was observed to spread transversely around the whole perimeter but not through the center of the fiber. This response was elicited only with pipettes of more than 6 µ diameter. The response was still present if the sodium of the Ringer solution was replaced by choline, or the chloride was replaced by nitrate or propionate. The duration of the response appeared to be independent of the duration of stimulating current in fresh fibers, while the contraction lasted as long as the current went on in deteriorated fibers. The contraction was first initiated at the area of fiber surface covered by the pipette, and spread around the perimeter of the fiber with a velocity of 0.8–6 cm/sec. Possible mechanisms of the response are discussed in connection with the properties of the transverse tubular system, the possibility of some self-propagating process along the walls of the tubules being suggested.

The Fibrillar Flight Muscles of Giant Water-Bugs: An Electron-Microscope Study

1967 ◽  
Vol 2 (3) ◽  
pp. 435-444
Author(s):  
DOREEN E. ASHHURST
Keyword(s):  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Flight Muscle ◽  
Muscle Fibres ◽  
Transverse Tubular System ◽  
Tropical Water ◽  
Tubular System ◽  
Flight Muscles ◽  
And Function ◽  
Water Bugs

The fibrillar flight muscles of several species of tropical water-bugs of the family Belostomatidae have been examined in the electron microscope. The myofibrils are very similar to those of the other fibrillar flight muscles which have been studied. The membrane systems, however, display features which appear to be peculiar to this family. The sarcoplasmic reticulum can be divided into three parts: a series of interconnecting vesicles surrounding the Z-lines, randomly scattered small vesicles around the myofibrils, and flattened cisternae which lie along the transverse tubular system, and form the dyads. These three components of the sarcoplasmic reticulum do not appear to be interconnected. The cisternae of the dyads contain an electrondense substance. The narrow tubules of the transverse tubular system or T-system penetrate deep into the fibre from the cell membrane. They follow a course roughly perpendicular to the myofibrils at the level of the M-lines. The dyads are scattered along their length, and may not be near a myofibril. Another system of very large vesicles is found in the muscle fibres, interspersed among the mitochondria. These vesicles usually appear to be empty; their nature and function are not at present known. Numerous mitochondria are present among the myofibrils. The peculiarities of the water-bug fibrillar flight muscle are discussed in relation to the flight muscles of other insects and the physiological properties of fibrillar flight muscle.

Sign in / Sign up

Export Citation Format

Share Document