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Scar tissue is composed of the same protein as the tissue that it replaces, but the fiber composition of the protein is different; instead of a random basketweave formation of the collagen fibers found in normal tissue, in fibrosis the collagen cross-links and forms a pronounced alignment in a single direction. [1]
In response to injury, this is called scarring, and if fibrosis arises from a single cell line, this is called a fibroma. Physiologically, fibrosis acts to deposit connective tissue, which can interfere with or totally inhibit the normal architecture and function of the underlying organ or tissue.
Damaged sweat and sebaceous glands, hair follicles, muscle cells, and nerves are seldom repaired. They are usually replaced by the fibrous tissue. The result is the formation of an inflexible, fibrous scar tissue. Human skin cells are capable of repairing UV-induced DNA damages by the process of nucleotide excision repair. [2]
A single satellite cell can proliferate and become a larger amount of muscle cells. [28] With the understanding that myosatellite cells are the progenitor of most skeletal muscle cells, it was theorized that if these cells could be grown in a lab and placed on scaffolds to make fibers, the muscle cells could then be used for food production. [29]
Sarcoplasm is the cytoplasm of a muscle cell. It is comparable to the cytoplasm of other cells, but it contains unusually large amounts of glycogen (a polymer of glucose), myoglobin, a red-colored protein necessary for binding oxygen molecules that diffuse into muscle fibers, and mitochondria.
Timing is important to wound healing. Critically, the timing of wound re-epithelialization can decide the outcome of the healing. [11] If the epithelization of tissue over a denuded area is slow, a scar will form over many weeks, or months; [12] [13] If the epithelization of a wounded area is fast, the healing will result in regeneration.
The scar presents T-cells and macrophages around blood vessels, with preservation of oligodendrocytes, but no signs of complement system activation. [25] Pattern II The scar presents T-cells and macrophages around blood vessels, with preservation of oligodendrocytes, as before, but also signs of complement system activation can be found. [26]
The unusual microscopic anatomy of a muscle cell gave rise to its terminology. The cytoplasm in a muscle cell is termed the sarcoplasm; the smooth endoplasmic reticulum of a muscle cell is termed the sarcoplasmic reticulum; and the cell membrane in a muscle cell is termed the sarcolemma. [9] The sarcolemma receives and conducts stimuli.