Muscle striation

Rhabdomyosarcoma/ medullomyoblastoma Like PNET muscle striations Desmin (S) muscle-specific actin Pineal cerebellum CNS... 

Figure 15.4 Printed primary human myoblasts and rat tenocytes to generate muscle-tendon tissues for substance testing. The cells were printed and immunostained for myosin heavy chain (green) in (a) and collagen I (green) in (b) for muscle and tendon tissues, respectively. In (c) the close-up of (a) shows the characteristic muscle striation and multinucleated cell bodies of differentiated myoblasts. Nuclei are stained in blue with (4, 6-diamidino-2-phenylindole). In (d) the close-up of (b) shows the characteristic mature tendon collagen I pattern around the cell nuclei, which are stained in red with propidium iodide. Scale for (a) and (b) = 1 mm. Scale for (c) and (d) = 20 pm.

Huxley, H.E. Hanson, J. (1954). Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation. Nature 173,973-976. 

Vernino, S. and Lennon, V. A. Ion channel and striational antibodies define a continuum of autoimmune neuromuscular hyperexcitability. Muscle Nerve 28 702-707, 2002. 

Smooth muscle is closer to non-muscle cells. No regular striations are visible and the contractions are much slower. Smooth muscle is found in the blood vessels, gut, skin, eye pupils, urinary and reproductive tracts. Smooth muscles form a very heterogeneous group of tissues, and the properties of vascular smooth muscles dilfer greatly from those in the airway, gut or reproductive tract. 

Smooth muscle is composed of spindle-shaped cells rather than fibres. It lacks striations since adjacent myofibrils are out of register. Power output is lower than that from skeletal muscle it is responsible for the gentler, involuntary movements including, for example, those that cause movement of the intestine and those that change the diameter of blood vessels. 

The striation of the muscle fibers is characteristic of skeletal muscle. It results from the regular arrangement of molecules of differing density. The repeating contractile units, the sarcomeres, are bounded by Z lines from which thin filaments of F-actin (see p. 204) extend on each side. In the A bands, there are also thick parallel filaments of myosin. The H bands in the middle of the A bands only contain myosin, while only actin is found on each size of the Z lines. 

Fascia (the tissue that encases muscles) advantage aside, this could be a bad idea. The argument is that since MCT is a food product made from fatty acids and glycerol it could not hurt them. Well, many things good to eat could hurt you very bad if injected into the body To be honest I have heard of no negative side effects as of yet except for the obvious loss of striations in delts and triceps, or when a vein was accidentally localized. I was of two minds on Synthol use until a year ago. 

Smooth muscle has no regular striations and the contractions are much slower. Smooth muscle is found in the blood vessels, gut, skin, eye pupils and urinary and reproductive tracts. 

We will first look at the role of calcium in the contraction of striated muscle. Figure 6.2a shows a light-microscopic picture of heart muscle. The striations are oriented perpendicularly to the longitudinal axis of the cells. The borders between the individual heart muscle cells are bridged by gap junctions, which will ensure swift spread of excitation from one cell to the next. Skeletal muscle cells form long syncytia in which the excitation spreads even faster. 

Figure 6.2. Ultrastructure of heart muscle, a Light microscopy. Striations mn perpendicularly to the cell longitudinal axis. Junctions between individual cells ( intercalated disks ) are visible as slightly lighter bands they contain numerous gap junctions, b Electron microscopy (EM), and correlation to hght microscopy (LM) and spatial arrangement of actin and myosin.

Smooth muscles derive their name from their appearance when viewed in polarized light microscopy in contrast to cardiac and skeletal muscles, which have striations (appearanee of parallel bands or lines), smooth muscle is unstriated. Striations result from the pattern of the myofilaments, actin and myosin, which line the myofibrils within each muscle cell. When many myofilaments align along the length of a muscle cell, light and dark regions create the striated appearance. This microscopic view of muscle reveals some hint of how muscles alter their shape to induce movement. Because muscle cells tend to be elongated, they are often called muscle fibers. Muscle cells are distinct from other cells in the body in shape, protein composition, and in the fact that they are multi-nucleated (have more than one nucleus per cell). 

SLE systemic lupus erythrematosus. smooth muscle (involuntary muscle plain muscle) Unlike striated muscle, smooth muscle has no cross-striations under the microscope, indicating an organization characteristic of muscle controlled by the autonomic nervous system, and reacts more slowly to neurotransmitters than striated muscle (skeletal muscle) of the voluntary nervous system. 

The fine axial orientation of troponin T was then demonstrated using the antibodies against chymotryptic troponin T subfragments, i.e., troponin T1 (MW 18,700) and troponin T2 (MW 11,900) of chicken skeletal muscle (Ohtsuki, 1979b). Anti-troponin T2 stained the same position as that stained by the antibodies against troponin I and C, whereas antitroponin T1 stained a position 13 nm toward the Z line from that stained by anti-troponin T2. Thus each member of the striation pair formed by anti-troponin T was proved to be derived from different regions in the molecule. 

On separated thin filaments of rabbit skeletal muscle, anti-troponin T1 formed a relatively wide striation at the same position as in the case of chicken skeletal muscle. The Fab fragment of the antibody formed a narrow striation at a position corresponding to the top side of the filament of the wide striation formed by y-globulin (1. Ohtsuki, unpublished results). This is consistent with the latter explanation at least for the orientation of the antigenic regions in troponin Ti. A possible arrangement of troponin Ti and T2 regions in the thin filament is shown in Fig. 10. 

Julius Cohnheim (1839-1884). German pathologist, professor at the universities of Kiel, Breslau, and Leipzig. Worked mainly on inflammation ( theory of alteration ), the fine structure of striated muscle ( Cohnheim striation ), infarction, and the etiology of tumors. 

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