The last decade has generated a multitude of studies using in vitro model systems to explore growth and differentiation of the nervous system. Although the findings have been exciting and have revealed unique properties of neural cells, considerable concern continues to be expressed regarding the significance of in vitro findings in terms of their applicability to in vivo biological events. To examine this issue further, a group of scientists pre sented and discussed their findings at a conference sponsored by the Institute of Developmental Neuroscience and Aging held in Crete, Greece, 26-29...