A star-shaped structure, composed of microtubules, which surrounds the centrioles during mitosis in animals. The aster forms during prophase. The spindle fibers arise gradually between the two asters (at opposite ends of the cell) until they attach to the kinetochores of the centromeres of each chromosome. Asters are not found in vascular plant cells.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

As"ter (as"tər), n. [L. aster aster, star, Gr. 'asth`r star. See Star.]

1. (Bot.)

A genus of herbs with compound white or bluish flowers; starwort; Michaelmas daisy.

2. (Floriculture)

A plant of the genus Callistephus. Many varieties (called China asters, German asters, etc.) are cultivated for their handsome compound flowers.

© Webster 1913

As"ter, n. (Biol.)

A star- shaped figure of achromatic substance found chiefly in cells dividing by mitosis.

© Webster 1913