Mitotic Apparatus(redirected from Spindle apparatus)
Also found in: Dictionary, Medical, Wikipedia.
mitotic apparatus[mī¦täd·ik ‚ap·ə′rad·əs]
a temporary structure in a dividing cell that enables the chromosomes to move to the poles of the cell, thus ensuring their even distribution between the daughter cells.
The mitotic apparatus consists of centrioles with the centre-spheres surrounding them, a cell division spindle with a system of microtubules, and an intermediate substance. Depending on the degree of development of astral rays around the centre-sphere, the mitotic apparatus is classified as astral (characteristic of most animal cells) or anastral (characteristic of plant cells). The mitotic apparatus is formed from macromolecules present in the interphase cell and from material synthesized before division. Its main components are ribonucleoproteins (about 90 percent proteins and 6 percent ribonucleic acid [RNA]). It also contains polysaccharides, lipids, and adenosine triphosphatase.
The proteins of the mitotic apparatus are contractile and are similar to muscle proteins in their amino acid composition. Usually, the mitotic apparatus starts to develop during prophase, is fully developed in metaphase, and begins to disintegrate in anaphase. Impairment of synthesis and injury to the mitotic apparatus result in mitotic pathology.