WHAT INSIGHTS INTO THE PHENOMENA OF CELL FATE DETERMINATION AND CELL-MIGRATION HAS THE STUDY OF THE URODELE NEURAL CREST PROVIDED

In this review we ask whether studies on the development of the urodel e neural crest (NC) have provided special insights into the fate and m igration of these cells when compared to other amphibian embryos or th ose of higher vertebrates. We recognize that during the first half of this century and even before, urodele embryos were the favorite object s of experimental embryology for studying the development of mesenchym al derivatives and their participation, together with mesodermal mesen chyme, in the development of the neuro- and viscerocranium. Furthermor e,the NC was discovered to be the source of cranial sensory and spinal ganglia, and the influence of the somites on the localization of the latter was clearly pointed out. In addition, pioneering studies were d evoted to the NC-derived pigment cells. Investigations in this field c oncentrated on their migration in the embryo and in vitro, and on the mechanisms underlying larval pigment pattern formation. It is mainly i n these three areas that the urodele embryo has served as a tool for g aining major results and defining the concepts of classical embryology . Even today, when the interest has shifted towards the molecular biol ogy in Xenopus, chicks and mice, the urodele embryo with its large cel ls, convenient for injections, is a potential model for future lineage studies and knockout experiments. And furthermore, as important conce pts of vertebrate development are defined in the urodele, future studi es in these embryos may link the disciplines of development and evolut ion.