Sarcoplasts

Part of speech: noun

Definitions

1. The cytoplasm of a muscle fiber, the material surrounding its nuclei and myofibrils inside the cell membrane
2. Cell matter within a muscle fibre that holds the contractile filaments and the nuclei of the muscle cell
3. Specialized cytoplasm in striated muscle cells that contains the organelles and contractile proteins needed for movement

Etymology: "Sarcoplasts" is the plural of "sarcoplast," a term built from two Greek-derived elements: "sarco-," from Greek "sarx" meaning flesh, and "-plast," from Greek "plastos," meaning formed or moulded. Put together, the sense is something like "flesh-moulded" or "formed in flesh," a fitting label for the substance that fills a muscle fibre. The "-plast" element is the more familiar of the two in biology. It appears in "chloroplast" and "cytoplast," where it names a structure or body within a cell. "Sarco-" is the same combining form found in "sarcoma," a cancer of connective tissue, and "sarcolemma," the membrane enclosing a muscle fibre. The prefix therefore marks the term as belonging to muscle tissue specifically, while the suffix places the substance within the cell.