WNT signals control FGF-dependent limb initiation and AER induction in the chick embryo Evidence that FGF8 signalling from the midbrain-hindbrain junction regulates growth and polarity in the developing midbrain Motor neuron columnar fate imposed by sequential phases of Hox-c activity Vertebrate limb bud development: moving towards integrative analysis of organogenesis BMPR-IA signaling is required for the formation of the apical ectodermal ridge and dorsal-ventral patterning of the limb