| transverse tubule | <cell biology> Invagination of the plasma membrane (sarcolemma) of striated muscle that lies between two tubular portions of the endoplasmic (sarcoplasmic) reticulum to form a triad of membrane profiles adjacent to the A band/I band junction in some cases, in other cases to the Z disc, of the resting sarcomere. Depolarisation of the T tubule membrane triggers the release of calcium from the sarcoplasmic reticulum and eventually muscle contraction. (18 Nov 1997) |
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| T tubule | <cell biology> Invagination of the plasma membrane (sarcolemma) of striated muscle that lies between two tubular portions of the endoplasmic (sarcoplasmic) reticulum to form a triad of membrane profiles adjacent to the A band/I band junction in some cases, in other cases to the Z disc, of the resting sarcomere. Depolarisation of the T tubule membrane triggers the release of calcium from the sarcoplasmic reticulum and eventually muscle contraction. (18 Nov 1997) |
| uriniferous tubule | The functional unit of the kidney, composed of a long convoluted portion (nephron) and an intrarenal collecting duct. (05 Mar 2000) |