microtubule(redirected from Spindle fibre)
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Related to Spindle fibre: centriole, chromatid, anaphase, metaphase, mitotic spindle, Spindle fibers
any of the slender, tubular structures, composed chiefly of tubulin, found in the cytoplasmic ground substance of nearly all cells; they are involved in maintenance of cell shape and in the movements of organelles and inclusions, and form the spindle fibers of mitosis.
A hollow, cylindric cytoplasmic element, 25 nm in diameter and of variable length, that occurs widely in the cytoskeleton, cilia, and flagella of cells; microtubules play a role in the maintenance of cell shape and increase in number during mitosis and meiosis, in which they are related to movement of the chromosomes by the nuclear spindle.
Any of the cylindrical hollow tubulin-containing structures that are found in the cytoplasm, cilia, and flagella of eukaryotic cells and are involved in determining cell shape and structure and directing the movement of organelles and chromosomes. Microtubules, along with microfilaments and intermediate filaments, make up a cell's cytoskeleton.
microtubuleA cylindrical tube measuring 20–25 nm in diameter, composed of protofilaments which are in turn composed of alpha- and beta-tubulin polymers. Each microtubule is polarised: at one end (the negative (-) end), alpha-subunits are exposed; at the other end (the positive (+) end), beta-subunits are exposed. Microtubules act as a scaffolding to determine cell shape, and provide a matrix on which cell organelles and vesicles move, a process requiring motor proteins, including kinesin (which moves towards the (+) end of the microtubule) and dynein (which generally moves towards the (-) end). Microtubules also form the spindle fibres for separating chromosomes during mitosis.
A cylindric cytoplasmic element that occurs widely in the cytoskeleton of plant and animal cells; microtubules increase in number during mitosis and meiosis, where they may be related to movement of the chromosomes or chromatids on the nuclear spindle during nuclear division.
neurotubulea hollow filament about 20–25 nm in diameter found in EUKARYOTE cells, composed of ACTIN-like protein called tubulin. Microtubules are thought to make up the CYTOSKELETON of the cell, the spindle fibres of MEIOSIS and MITOSIS, (See also COLCHICINE and, in some cells of plants and animals, form the 9 + 2 structure of the CILIUM and FLAGELLUM.
A cylindric cytoplasmic element that occurs widely in the cytoskeleton of plant and animal cells; microtubules increase in number during mitosis and meiosis.