An asymmetric cell division produces two daughter cells with different cellular fates. This is in contrast to symmetric cell divisions which give rise to daughter cells of equivalent fates. Notably, stem cells divide asymmetrically to give rise to two distinct daughter cells: one copy of the original stem cell as well as a second daughter programmed to differentiate into a non-stem cell fate. (In times of growth or regeneration, stem cells can also divide symmetrically, to produce two identical copies of the original cell.[1])
In principle, there are two mechanisms by which distinct properties may be conferred on the daughters of a dividing cell. In one, the daughter cells are initially equivalent but a difference is induced by signaling between the cells, from surrounding cells, or from the precursor cell. This mechanism is known as extrinsic asymmetric cell division. In the second mechanism, the prospective daughter cells are inherently different at the time of division of the mother cell. Because this latter mechanism does not depend on interactions of cells with each other or with their environment, it must rely on intrinsic asymmetry. The term asymmetric cell division usually refers to such intrinsic asymmetric divisions.[2]