| 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) |
|---|---|
| tubule | 1. A small pipe or fistular body; a little tube. 2. <anatomy> A minute tube lined with glandular epithelium; as, the uriniferous tubules of the kidney. Origin: F. Tubule, or L. Tubulus, dim. Of tubus a tube, a pipe. Source: Websters Dictionary (01 Mar 1998) |
| uriniferous tubule | The functional unit of the kidney, composed of a long convoluted portion (nephron) and an intrarenal collecting duct. (05 Mar 2000) |