Intrinsic vs. extrinsic modes of asymmetric cell division. (A). During the intrinsic mode of asymmetric division, cells such as Drosophila neuroblasts possess an inherent axis of polarity. This polarity allows certain proteins such as cell fate determinants to localize asymmetrically within the cells. The mitotic spindle orients itself to be along the same axis of polarity, so when cellular division occurs, only one daughter cell receives the aforementioned determinants. Each daughter cell thus has a different fate. (B) During the extrinsic mode of asymmetric division, cellular precursors receive external, or extracellular, signals to self-renew (yellow). The mitotic spindle is oriented perpendicular to these external signals. When cellular division occurs, only one of the daughter cells continues to receive these signals and the two cells therefore have different fates.