scholarly journals THE SARCOPLASMIC RETICULUM AND ITS ASSOCIATION WITH THE T SYSTEM IN AN INSECT

1967 ◽  
Vol 32 (3) ◽  
pp. 535-545 ◽  
Author(s):  
Martin Hagopian ◽  
David Spiro
Keyword(s):  
Fine Structure ◽  
Sarcoplasmic Reticulum ◽  
Cell Surface ◽  
Osmium Tetroxide ◽  
Surface Membrane ◽  
Transverse Tubular System ◽  
Leucophaea Maderae ◽  
Tubular System ◽  
Femoral Muscle ◽  
T System

The fine structure of the sarcoplasmic reticulum and the transverse tubular system of the femoral muscle of the cockroach, Leucophaea maderae, was studied after prefixation in glutaraldehyde, postfixation in osmium tetroxide, and embedding in Epon. The sarcoplasmic reticulum in this muscle reveals features not previously reported. The sarcoplasmic reticulum is abundant, consisting mainly of a fenestrated envelope which surrounds each myofibril at all levels in the sarcomere. This sarcoplasmic reticulum envelope is continuous transversally as well as longitudinally along the myofibrils. Dyadic junctions are formed by a single T system element which contacts the unfenestrated sarcoplasmic reticulum of adjacent myofibrils in an alternating manner at the ends of the A band. At the dyads, regularly spaced thickenings of the sarcoplasmic reticulum membranes bordering the dyadic spaces are noted. These thickenings, however, do not contact the T tubule membrane. Typical dyadic contacts also are seen between the cell surface membrane and sarcoplasmic reticulum. Z line-like material is seen in contact with the membranes of the cell surface and longitudinal branches of the T systems.

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 ELECTROMECHANICAL COUPLING IN TUBULAR MUSCLE FIBERS

1972 ◽  
Vol 52 (3) ◽  
pp. 626-638 ◽  
Author(s):  
Arieh Gilai ◽  
I. Parnas
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cell Membrane ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Hexagonal Array ◽  
Thin Filaments ◽  
Transverse Tubular System ◽  
The Core ◽  
Tubular System ◽  
Terminal Cisternae

The tubular fibers of the claw-closer muscle of the scorpion have a central core containing nuclei and mitochondria. The myofibrils have the shape of thin lamellae (1 µ) extending radially from the core to the surface membrane (20 µ). The thick myofilaments are organized in a hexagonal array with orbits of 10–13 thin myofilaments. The ratio of thick-to-thin filaments is 1:5. Transverse tubular system (TS) openings are located between lamellated myofibrils. In each sarcomere two TS's are found, one on each side of the H band. The TS is composed of a transverse tubule and tubular pockets (TP). The TP's form diadic contact with the terminal cisternae of the sarcoplasmic reticulum. The TS can be traced from the cell membrane down to the cell core. The surface area of the TS was calculated to be six times that of the outer surface membrane.

scholarly journals THE FINE STRUCTURE OF SHEEP MYOCARDIAL CELLS; SARCOLEMMAL INVAGINATIONS AND THE TRANSVERSE TUBULAR SYSTEM

1962 ◽  
Vol 12 (1) ◽  
pp. 91-100 ◽  
Author(s):  
F. O. Simpson ◽  
S. J. Oertelis
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Electron Microscope ◽  
Cell Surface ◽  
Electron Microscope Study ◽  
Myocardial Cells ◽  
Transverse Tubular System ◽  
Tubular System ◽  
A Cell ◽  
Anatomical Evidence

An electron microscope study of sheep myocardial cells has demonstrated the presence of a transverse tubular system, apparently forming a network across the cell at each Z band level. The walls of these tubules resemble the sarcolemma in consisting of two dense layers—plasma membrane and basement menbrane; continuity of the tubule walls with the sarcolemma can be seen when longitudinal sections of a cell are obtained between two subsarcolemmal myofibrils and at the same time perpendicular to the cell surface. The demonstration of communication between the lumen of the transverse tubular system and the extracellular space appears to be more definite in this study than in any work hitherto published. It provides anatomical evidence of a possible direct pathway for transmission of the activating impulse from the sarcolemma to the myofibril Z bands.

Cell surface saccharides of Trypanosoma lewisi. I. Polycation-induced cell agglutination and fine-structure cytochemistry

1975 ◽  
Vol 19 (3) ◽  
pp. 621-644
Author(s):  
D.M. Dwyer
Keyword(s):  
Fine Structure ◽  
Cell Surface ◽  
Alcian Blue ◽  
Chondroitin Sulphate ◽  
Surface Membrane ◽  
Ruthenium Red ◽  
Surface Coat ◽  
Cell Agglutination ◽  
Trypanosoma Lewisi ◽  
Cationic Compounds

Trypanosoma lewisi bloodstream and culture forms were agglutinated differentially with low concentrations of the cationic compounds: ruthenium red, ruthenium violet, Alcian blue chloride, 1-hexadecylpyridinium chloride, lanthanum chloride, and cationized ferritin. The bloodstream form trypanosomes gave the highest agglutination levels with each of the compounds tested. Ruthenium red was the most effective inducer of cell agglutination among the several cations used. Trypsin-treated bloodstream forms were agglutinated less in the presence of ruthenium red than untreated controls. Ruthenium red-induced cell agglutination also was lowered with chondroitin sulphate and dextran sulphate, but not with alpha-D-glucose, alpha-D-mannose or with several methyl glycosides. Treatment of the bloodstream trypanosomes with alpha-amylase, dextranase, or neuraminidase had little effect on agglutination levels obtained with ruthenium red. Fine-structure cytochemical staining with ruthenium red, ruthenium violet, and Alcian blue-lanthanum nitrate was used to ascertain the presence and distribution of presumptive carbohydrates in the trypanosome cell surface. The extracellular surface coat of the bloodstream forms stained densely with each of the polycationic dyes. Trypsin treatment removed the surface coat from bloodstream trypanosomes; however, the surface membranes of the organisms were stained densely with the several dyes. Similar surface-membrane staining was obtained with the cationic compounds and the culture forms, which lack a cell surface coat. Cationized ferrin was used at the fine-structure level to visualize the negative surface charge present in the cell surface coat and external membrane of the several trypanosome stages. Results obrained from the agglutination and cytochemistry experiments indicate that complex polysaccharides are present in the surface membranes and cell surface coat of T. lewisi bloodstream forms. Similar conclusions also pertain to the surface membranes of the T. lewisi culture from trypanosomes. The carbohydrates probably represent glycopeptide and glycoprotein structural components of the surface membrane of this organism.

scholarly journals DIFFERENTIATION OF THE SARCOPLASMIC RETICULUM AND T SYSTEM IN DEVELOPING CHICK SKELETAL MUSCLE IN VITRO

1967 ◽  
Vol 35 (2) ◽  
pp. 405-420 ◽  
Author(s):  
Elizabeth B. Ezerman ◽  
Harunori Ishikawa
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Osmium Tetroxide ◽  
Muscle Cells ◽  
Simultaneous Occurrence ◽  
Chick Embryos ◽  
Developing Muscle ◽  
T System

The electron microscope was used to investigate the first 10 days of differentiation of the SR and the T system in skeletal muscle cultured from the breast muscle of 11-day chick embryos. The T-system tubules could be clearly distinguished from the SR in developing muscle cells fixed with glutaraldehyde and osmium tetroxide. Ferritin diffusion confirmed this finding: the ferritin particles were found only in the tubules identified as T system. The proliferation of both membranous systems seemed to start almost simultaneously at the earliest myotube stage. Observations suggested that the new SR membranes developed from the rough-surfaced ER as tubular projections. The SR tubules connected with one another to form a network around the myofibril. The T-system tubules were formed by invagination of the sarcolemma. The early extension of the T system by branching and budding was seen only in subsarcolemmal regions. Subsequently the T-system tubules could be seen deep within the muscle cells. Immediately after invaginating, the T-system tubule formed, along its course, specialized connections with the SR or ER: triadic structures showing various degrees of differentiation. The simultaneous occurrence of myofibril formation and membrane proliferation is considered to be important in understanding the coordinated events resulting in the differentiated myotube.

Sarcoplasmic reticulum and mitochondria as cation accumulation sites in smooth muscle

1973 ◽  
Vol 265 (867) ◽  
pp. 17-23 ◽  
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Divalent Cation ◽  
Electromechanical Coupling ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Relative Volume ◽  
Electron Dense Material ◽  
Tubular System ◽  
Central Elements

A tubular system of sarcoplasmic reticulum that is not penetrated by extracellular markers is described in vertebrate smooth muscles. The sarcoplasmic reticulum forms fenestrations around the surface vesicles and also forms close appositions (an approximately 10 to 12 nm gap traversed by periodic electron dense material) with the non-specialized surface membrane. The morphological couplings are considered to be the most probable sites of electromechanical coupling of the action potential to the twitch contraction. The relative volume of the sarcoplasmic reticulum varies in functionally different (tonic and phasic) smooth muscles, and correlates with the ability of the different smooth muscles to contract in the absence of extracellular calcium. Electron opaque deposits of strontium are accumulated by peripheral and central elements of the sarcoplasmic reticulum. The accumulation of strontium and barium by mitochondria raises the possibility that, in addition to the sarcoplasmic reticulum, mitochondria may play a role in the regulation of intracellular divalent cation levels in vertebrate smooth muscle.

scholarly journals Radial propagation of muscle action potential along the tubular system examined by potential-sensitive dyes.

1980 ◽  
Vol 76 (6) ◽  
pp. 751-762 ◽  
Author(s):  
S Nakajima ◽  
A Gilai
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Time Course ◽  
Surface Membrane ◽  
Simultaneous Recording ◽  
Conduction Delay ◽  
Muscle Action Potential ◽  
Tubular System ◽  
Intracellular Action ◽  
T System

Isolated single (Xenopus) muscle fibers were stained with a non-permeant potential-probing dye, merocyanine rhodanine (WW375) or merocyanine oxazolone (NK2367). When the fiber was massively stimulated, an absorption change (wave a), which seemed to reflect the action potential, occurred. Simultaneous recording of optical changes and intracellular action potentials revealed that the time-course of wave a was slower than the action potential: the peak of wave a was attained at 1 ms, and the peak of action potential was reached at 0.5 ms after the stimulation. This difference suggests that wave a represents the potential changes of the whole tubular membrane and the surface membrane, whereas the action potential represents a surface potential change. This idea was substantiated by recording absorption signals preferentially from the surface membrane by recording the absorption changes at the edge of the fiber. Wave a obtained by this method was as quick as the intracellular action potential. The value of radial conduction velocity of action potential along the T system, calculated by comparing the action potential with wave a, was 6.4 cm/s at 24.5 degrees C, in fair agreement with González-Serratos (1971. J. Physiol. [Lond.]. 212:777-799). The shape of wave a suggests the existence of an access delay (a conduction delay at the orifice of the T system) of 130 microseconds.

scholarly journals THE ORGANIZATION OF FLIGHT MUSCLE IN AN APHID, MEGOURA VICIAE (HOMOPTERA)

1965 ◽  
Vol 27 (2) ◽  
pp. 379-393 ◽  
Author(s):  
David S. Smith
Keyword(s):  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Cell Surface ◽  
Flight Muscle ◽  
Muscle Cells ◽  
Indirect Flight Muscle ◽  
Megoura Viciae ◽  
Flight Muscles ◽  
High Degree ◽  
T System

The organization of the indirect flight muscle of an aphid (Hemiptera-Homoptera) is described. The fibers of this muscle contain an extensive though irregularly disposed complement of T system tubules, derived as open invaginations from the cell surface and from the plasma membrane sheaths accompanying the tracheoles within the fiber. The sarcoplasmic reticulum is reduced to small vesicles applied to the T system surfaces, the intermembrane gap being traversed by blocks of electron-opaque material resembling that of septate desmosomes. The form and distribution of the T system and sarcoplasmic reticulum membranes in flight muscles of representatives of the major insect orders is described, and the extreme reduction of the reticulum cisternae in all asynchronous fibers (to which group the aphid flight muscle probably belongs), and the high degree of their development in synchronous fibers is documented and discussed in terms of the contraction physiology of these muscle cells.

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