Neuromuscular junction alterations in extraocular muscles of myotonic rats

1983 ◽  
Vol 41 ◽  
pp. 654-655
Author(s):  
Bruce R. Pachter ◽  
Arthur Eberstein
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Neuromuscular Junction ◽  
High Frequency ◽  
Light And Electron Microscopy ◽  
Extraocular Muscles ◽  
Dense Bodies ◽  
Myofibrillar Degeneration ◽  
Cell Vacuolization

Rats treated with 20,25-diazacholesterol manifest clinical as well as physiological signs characteristic of human myotonic dystrophy. The extraocular muscles (EOMs) of such myotonic rats were shewn in a prior study to exhibit by electromyography, prolonged insertion activity, high frequency bizzare discharges, and myotonic responses, which are comparable to that observed in skeletal muscle. Light and electron microscopy of the EOMs revealed numerous fiber alterations, i.e., dense bodies, atrophic and angulated fibers, cell vacuolization, dilation and proliferation of the sarcoplasmic reticulum, mu11ilamllar membranous bodies, atypical mitochondrial clusters and disruptions, mitochondrial inclusions, excessive lipid accumulations, and myofibrillar degeneration. Many of these changes have been reported in human myotonic peripheral musculature. The most susceptible fiber populations in the EOMs were found to be the pale, intermediate, and red singly-innervated fibers of the global region; the pale fibers were the most affected.

scholarly journals Congenital myopathy associated with the triadin knockout syndrome

Neurology ◽  
2017 ◽  
Vol 88 (12) ◽  
pp. 1153-1156 ◽  
Author(s):  
Andrew G. Engel ◽  
Keeley R. Redhage ◽  
David J. Tester ◽  
Michael J. Ackerman ◽  
Duygu Selcen
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Light And Electron Microscopy ◽  
Deltoid Muscle ◽  
Congenital Myopathy ◽  
Compound Heterozygous

Objective:Triadin is a component of the calcium release complex of cardiac and skeletal muscle. Our objective was to analyze the skeletal muscle phenotype of the triadin knockout syndrome.Methods:We performed clinical evaluation, analyzed morphologic features by light and electron microscopy, and immunolocalized triadin in skeletal muscle.Results:A 6-year-old boy with lifelong muscle weakness had a triadin knockout syndrome caused by compound heterozygous null mutations in triadin. Light microscopy of a deltoid muscle specimen shows multiple small abnormal spaces in all muscle fibers. Triadin immunoreactivity is absent from type 1 fibers and barely detectable in type 2 fibers. Electron microscopy reveals focally distributed dilation and degeneration of the lateral cisterns of the sarcoplasmic reticulum and loss of the triadin anchors from the preserved lateral cisterns.Conclusions:Absence of triadin in humans can result in a congenital myopathy associated with profound pathologic alterations in components of the sarcoplasmic reticulum. Why only some triadin-deficient patients develop a skeletal muscle phenotype remains an unsolved question.

scholarly journals CARDIAC MUSCLE

1968 ◽  
Vol 36 (3) ◽  
pp. 497-526 ◽  
Author(s):  
Joachim R. Sommer ◽  
Edward A. Johnson
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Guinea Pig ◽  
Cardiac Muscle ◽  
Extracellular Space ◽  
Light And Electron Microscopy ◽  
Rabbit Heart ◽  
Contraction Coupling ◽  
The Difference

With light and electron microscopy a comparison has been made of the morphology of ventricular (V) and Purkinje (P) fibers of the hearts of guinea pig, rabbit, cat, dog, goat, and sheep. The criteria, previously established for the rabbit heart, that V fibers are distinguished from P fibers by the respective presence and absence of transverse tubules is shown to be true for all animals studied. No evidence was found of a permanent connection between the sarcoplasmic reticulum and the extracellular space. The sarcoplasmic reticulum (SR) of V fibers formed couplings with the sarcolemma of a transverse tubule (interior coupling) and with the peripheral sarcolemma (peripheral coupling), whereas in P fibers the SR formed only peripheral couplings. The forms of the couplings were identical. The significance, with respect to excitation-contraction coupling, of the difference in the form of the couplings in cardiac versus skeletal muscle is discussed together with the electrophysiological implications of the differing geometries of bundles of P fibers from different animals.

scholarly journals Preparation and morphology of sarcoplasmic reticulum terminal cisternae from rabbit skeletal muscle.

1984 ◽  
Vol 99 (3) ◽  
pp. 875-885 ◽  
Author(s):  
A Saito ◽  
S Seiler ◽  
A Chu ◽  
S Fleischer
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Thin Section ◽  
Membrane Surface ◽  
Freeze Fracture ◽  
Morphological Characteristics ◽  
Negative Staining ◽  
Section Electron ◽  
Terminal Cisternae

We have developed a procedure to isolate, from skeletal muscle, enriched terminal cisternae of sarcoplasmic reticulum (SR), which retain morphologically intact junctional "feet" structures similar to those observed in situ. The fraction is largely devoid of transverse tubule, plasma membrane, mitochondria, triads (transverse tubules junctionally associated with terminal cisternae), and longitudinal cisternae, as shown by thin-section electron microscopy of representative samples. The terminal cisternae vesicles have distinctive morphological characteristics that differ from the isolated longitudinal cisternae (light SR) obtained from the same gradient. The terminal cisternae consist of two distinct types of membranes, i.e., the junctional face membrane and the Ca2+ pump protein-containing membrane, whereas the longitudinal cisternae contain only the Ca2+ pump protein-containing membrane. The junctional face membrane of the terminal cisternae contains feet structures that extend approximately 12 nm from the membrane surface and can be clearly visualized in thin section through using tannic acid enhancement, by negative staining and by freeze-fracture electron microscopy. Sections of the terminal cisternae, cut tangential to and intersecting the plane of the junctional face, reveal a checkerboardlike lattice of alternating, square-shaped feet structures and spaces each 20 nm square. Structures characteristic of the Ca2+ pump protein are not observed between the feet at the junctional face membrane, either in thin section or by negative staining, even though the Ca2+ pump protein is observed in the nonjunctional membrane on the remainder of the same vesicle. Likewise, freeze-fracture replicas reveal regions of the P face containing ropelike strands instead of the high density of the 7-8-nm particles referable to the Ca2+ pump protein. The intravesicular content of the terminal cisternae, mostly Ca2+-binding protein (calsequestrin), is organized in the form of strands, sometimes appearing paracrystalline, and attached to the inner face of the membrane in the vicinity of the junctional feet. The terminal cisternae preparation is distinct from previously described heavy SR fractions in that it contains the highest percentage of junctional face membrane with morphologically well-preserved junctional feet structures.

Ultrastructural Hepatic Changes Induced by Electrocution

1967 ◽  
Vol 25 ◽  
pp. 152-153
Author(s):  
B. H. Schofield ◽  
I. W. Grossman
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Hepatic Cell ◽  
Capra Hircus ◽  
Ground Substance ◽  
Cytoplasmic Vacuolization ◽  
Angora Goats ◽  
Cytoplasmic Ground Substance ◽  
Cell Vacuolization ◽  
Ballistic Trauma

During the course of investigations of ballistic trauma-induced hepatic changes in the goat, cytoplasmic hepatic cell vacuolization was observed in those animals killed by electrocution. To determine the pathogenesis of these vacuoles six castrated Texas Angora goats (Capra hircus) were electrocuted with 60 cycle a-c, 120 ± 5 volts, wall current with a rectal electrode and tongue electrode. Three goats killed with intravenous pentobarbital served as control animals.We consistently observed hepatic cell cytoplasmic vacuolization by light and electron microscopy in the electrocuted goats (Figure 1 and Figure 2). These vacuoles were bounded by a single smooth-surfaced membrane and a thin rim of amorphous cytoplasmic ground substance. The vacuoles occasionally distended the hepatocytes and measured up to 18μ in greatest diameter.

scholarly journals FILAMENT ULTRASTRUCTURE AND ORGANIZATION IN VERTEBRATE SMOOTH MUSCLE

1967 ◽  
Vol 35 (2) ◽  
pp. 303-321 ◽  
Author(s):  
Bernard J. Panner ◽  
Carl R. Honig
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Actin Filaments ◽  
Heavy Meromyosin ◽  
Dense Bodies ◽  
Contraction Mechanism ◽  
Dark Staining ◽  
Technical Factors ◽  
Low Ionic Strength

Using a variety of preparative techniques for electron microscopy, we have obtained evidence for the disposition of actin and myosin in vertebrate smooth muscle. All longitudinal myofilaments seen in sections appear to be actin. Previous reports of two types of longitudinal filaments in sections are accounted for by technical factors, and by differentiated areas of opacity along individual filaments. Dense bodies with actin emerging from both ends have been identified in homogenates, and resemble Z discs from skeletal muscle (Huxley, 1963). In sections, short, dark-staining lateral filaments 15–25 A in diameter link adjacent actin filaments within dense bodies and in membrane dense pataches. They appear homologous with Z-disc filaments. Similar lateral filaments connect actin to plasma membrane. Dense bodies and dense patches, therefore, are attachment points and denote units analogous to sarcomeres. In glycerinated, methacrylate-embedded sections, lateral processes different in length and staining characteristics from lateral filaments in dense bodies exist at intervals along actin filaments. These processes are about 30 A wide and resemble heavy meromyosin from skeletal muscle. They also resemble heads of whole molecules of myosin in negatively stained material from gizzard homogenates. Intact single myosin molecules and dimers have been found, both free and attached to actin, even in media of very low ionic strength. Myosin can, therefore, exist in relatively disaggregated form. Models of the contraction mechanism of smooth muscle are proposed. The unique features are: (1) Myosin exists as small functional units. (2) Movement occurs by interdigitation and sliding of actin filaments.

scholarly journals Myosin VI in skeletal muscle: its localization in the sarcoplasmic reticulum, neuromuscular junction and muscle nuclei

2012 ◽  
Vol 139 (6) ◽  
pp. 873-885 ◽  
Author(s):  
Justyna Karolczak ◽  
Magdalena Sobczak ◽  
Łukasz Majewski ◽  
Marine Yeghiazaryan ◽  
Anna Jakubiec-Puka ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Neuromuscular Junction ◽  
Myosin Vi

Histogenesis of Human Extraocular Muscles and Its Innervation

1977 ◽  
Vol 35 ◽  
pp. 564-565
Author(s):  
A. Julio Martinez ◽  
M. Barmada
Keyword(s):  
Electron Microscopy ◽  
Gestational Age ◽  
Light And Electron Microscopy ◽  
Abducens Nerve ◽  
Extraocular Muscles ◽  
Oculomotor Nerve ◽  
Paraxial Mesoderm ◽  
Optic Vesicle ◽  
Trochlear Nerve ◽  
Embryonic Myogenesis

Embryonic myogenesis and neurogenesis of human extraocular muscles (EOM) were studied by light and electron microscopy in a group of embryos and fetal specimens (6 to 24 weeks gestational age) (20 to 200 mm CR length).The earliest trace of EOM in humans have been reported at 7 mm (4 weeks) as a single undifferentiated mass of condensed paraxial mesoderm surrounding the optic vesicle. There is no separation between individual muscles. The distinction occurs before the 20 mm stage (6-7 weeks) when the 4 recti and the 2 obliques can be recognized(1). The oculomotor nerve can be identified as an elongation of the midbrain at 12.2 mm (5th week). The trochlear nerve appears between the 6th and 7th weeks and the abducens nerve is recognizable first at 31.3 mm (8th week). By the end of the 8th week, all the nerves had reached their respective muscles.

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