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Tracheid |
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tracheid [′trā·kē·əd]
(botany) An elongate, spindle-shaped xylem cell, lacking protoplasm at maturity, and having secondary walls laid in various thicknesses and patterns over the primary wall. Tracheid a dead lignified plant cell that functions in water conduction. Tracheids are found in the xylem of all higher plants except certain angiosperms, such as cereals and sedges, in which the water-conducting function is performed by vessels, or tracheae. Tracheids are usually polygonal in cross section; their walls have annular, spiral, or scalene thickenings or rimmed pores. The cells range in length from fractions of a millimeter to 3–5 mm (pine, larch) and even 10 mm (agave). In the process of evolution, tracheids developed into fibrous tracheids with limited water-conducting ability and into specialized mechanical elements known as libriform fibers. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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No references found | 34)) The use of TEM greatly extended LM observations, providing information on ultrastructural features of tracheid walls in the surface layers of boards where delignification from chemical pretreat-ment was greatest as well as of tracheid walls in deeper layers of cells, representing early to intermediate stages of delignification. Tracheid to parenchyma pit pairs may have porose pit membranes on the tracheid side and nonporose pit membranes on the parenchyma side; thus degree of porosity in a section can represent the degree to which one primary wall or the other is pared away. As the tracheid cytoplasm undergoes autolysis, the matrix materials in pit membranes of Metasequoia are removed from both torus and margo regions. |
Tracheid |
Tracheal stenosis Tracheal stenosis Tracheal stenosis tracheal transection tracheal transection tracheal tube tracheal tube tracheal tube Tracheal tubes Tracheal tubes tracheal tugging tracheal vein tracheal vein tracheal veins tracheal veins tracheal veins tracheal/bronchial rupture trachealgia Trachearia Tracheary Tracheary tracheary element tracheas tracheas tracheas Tracheata Tracheata tracheate tracheate tracheate Tracheid tracheidaltracheidal Tracheids Tracheids tracheitis tracheitis tracheitis Tracheitis bacterial Tracheitis bacterial Tracheitis bacterial trachel(o)- trachel- trachelagra trachelectomy trachelematoma Trachelidan Trachelipod Trachelipoda Trachelipodous trachelism trachelismus trachelitis trachelitis trachelitis Trachelium trachelo- Trachelobranchiate trachelobregmatic diameter trachelocystitis trachelocystitis | |||||||
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