RETINOIC ACID AS A CHEMOTACTIC MOLECULE IN NEURONAL DEVELOPMENT

We describe the results of experiments on dissociated cultures of embr yonic chick neural tissue which were designed to investigate further t he role of all-trans-retinoic acid (tRA) on neurite outgrowth and, by inference, on the developing nervous system in vivo. We show that tRA increases both the number of neurites and the length of neurites exten ding from these chick neural tube cells at nM concentrations. Secondly , using the newly designed Dunn chamber in which stable gradients of c ompounds can be generated, we show that neurites respond to a gradient of tRA by growing up the gradient. These observations indicate a role for RA in vivo, not only in the initial outgrowth of neurites, but al so in their guidance to the appropriate targets. (C) 1998 ISDN. Publis hed by Elsevier Science Ltd.