noun, plural: asters
(cell biology) A star-shaped cluster of microtubules radiating from the pericentriolar region, and seen immediately before and during mitosis of an animal cell.
(botany) A plant genus of the family Asteraceae; the flower of this group.
In cells, the role of astral microtubules in mitosis is to ensure correct positioning and orientation of the mitotic spindle apparatus based on cell polarity. Although this function is essential in mitosis, the process does not strictly require astral microtubules to progress.