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Related to Sarcoplasm: myofibril


Hyaline, semifluid interfibrillar substance of striated muscle tissue.



the cytoplasm of smooth-muscle cells and striated and myocardial muscle fibers. The matrix, or basic material, of sarcoplasm contains glycolytic enzymes and other globular proteins, for example, myoglobin; it also contains salts, polyphosphates, and glycogen, which is depleted during muscle contraction. Sarcoplasm surrounds nuclei and fills the space between myofibrils. It contains ribosomes, mitochondria (sarcosomes), and a complex system of membrane-bound vesicles, tubules, and cisterns, all of which are combined into a continuous sarcoplasmic reticulum.

The sarcoplasmic reticulum is divided into two parts. One part is oriented along the myofibrils and is equivalent to the endoplasmic reticulum found in other types of cells. The other part is oriented across a muscle fiber and forms the T system, which is a system that conducts impulses from the surface to deep within a muscle fiber and, in some places, changes into sarcolemma. The sarcoplasmic reticulum probably transmits excitation within a fiber. It also contains the Marsh factor, which inhibits the activity of the enzyme adenosine triphosphatase. The amount of sarcoplasm varies in different striated fibers: collagenous fibers contain little sarcoplasm, whereas red fibers contain a great deal.


References in periodicals archive ?
156,157) These mutations allow excessive calcium release from the sarcoplasmic reticulum into the sarcoplasm, resulting in intense muscle contraction.
Abnormal Internal nucleus Fiber containing [greater than muscle tissue or equal to] 1 internally located nuclei (2 [micro]m or 8 pixels of sarcoplasm between nucleus and sarcolemma).
Muscle tissues had small, focal areas of sarcoplasm degeneration, hyalinization or lysis, with mild to moderate proliferation of sarcolemmal nuclei (Fig.
These have tubular mitochondria and a small number of sarcoplasmic reticula around the sarcolemma and some glycogen granules in the sarcoplasm (Fig.
In HRSEM images, the sarcolemma lamina was seen to be adhering to the sarcoplasm and the collagen fiber network of the endomysium was observed to be in close proximity to the sponge-like structure of the basal lamina.
The nuclei are normally located in the lateral luminal protrusions of the sarcoplasm.
Electron microscopy, however, is essential for diagnosis, demonstrating the rods as electron-dense structures in the sarcoplasm.
These included limited areas of elongated myocardial fibers, hypertrophied cardiomyocytes, and slight interstitial edema as well as small clusters of "wavy" myocytes with condensed sarcoplasm and preserved nuclei.