NEURAL STEM-CELLS - FROM FLY TO VERTEBRATES

Our goal in this review is to explore the relationship between Drosoph ila and vertebrate neural stem cell development by comparing progress in each system with the aim of answering several central questions in stem cell biology: (a) How are stem cells formed? (b) Do stem cells di vide symmetrically or asymmetrically? (c) How is stem cell fate mainta ined? (d) How is stem cell differentiation initiated? (e) How are diff erent stem cell fates determined? (f) How ''plastic'' are different ne ural stem cell fates? (g) How do neural stem cells produce different p rogeny? and (h) What regulates stem cell proliferation versus quiescen ce? Not surprisingly, research in Drosophila and vertebrate systems ea ch have their own biases, strengths, and weaknesses; we hope that by d irectly comparing progress in each held, new experiments and interpret ations in both vertebrate and Drosophila research will become apparent . It has become increasingly clear that vertebrates and Drosophila sha re many fundamental mechanisms of neurogenesis, validating a (C) 1998 John Wiley & Sons, Inc.