Yelon, D. and Stainier, D.Y.R. (2002) Pattern formation: swimming in retinoic acid. Current biology : CB. 12(2):R707-709.
The metabolite retinoic acid has been implicated as a key player during anterior-posterior patterning in vertebrate embryos. Recent studies in zebrafish extend this model by demonstrating the influence of retinoic acid on endoderm regionalization.