The role of positive and negative signals in somite patterning.

Signals from the axial tissues, neural tube and notochord play a crucial role in patterning cell fates in adjacent somitic tissue. Work over the past four decades has indicated how signals from the axial tissues, as well as the surface ectoderm and lateral plate mesoderm, together act to pattern somitic cell fate. Furthermore, recent results have shed light on how some of these molecules control the specification and migratory behaviour of somitic cells.