microtubules

n. thin tube-like organ in a cell that is used for transporting material within a cell

Microtubules are one of the components of the cytoskeleton. They have diameter of ~ 24 nm and length varying from several micrometers to possibly millimeters in axons of nerve cells. Microtubules serve as structural components within cells and are involved in many cellular processes including mitosis, cytokinesis, and vesicular transport.
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Noun
1. a microscopically small tubule
(hypernym) tubule

n. microtubule, thin tube-like organ in a cell that is used for transporting material within a cell