Mechanisms of asymmetric cell division: two Bs or not two Bs, that is the question.

Abstract

How sister cells have different fates is a fundamental aspect of the problem of how cell diversity is generated during development. In principle, sister cells that are different could be produced in two distinct ways. First, polar mother cells could divide to generate daughters that are different from the time they are formed. Alternatively, two identical sisters could be generated and become different as a consequence of some later event. Consideration of these mechansisms raises immediate further questions: What causes a mother cell to be polar? How do initially identical sister cells become different? And in each case, how do initial differences in sister cells lead to their ultimately distinct fates? Answers to these questions would provide important insights into the mechanisms responsible for the control of development. In this review we use the term "asymmetric cell division" to refer to any cell division in which sister cells have different fates...