Int. J. Dev. Biol. 51: 447 - 461 (2007)
doi: 10.1387/ijdb.072327as
© UBC Press

The preplacodal region: an ectodermal domain with multipotential progenitors that contribute to sense organs and cranial sensory ganglia

Andrea Streit*

Department of Craniofacial Development, King's College London, Guy's Campus, London, UK

ABSTRACT The otic primordium belongs to a group of related structures, the sensory placodes that contribute to the paired sense organs - ear, eye and olfactory epithelium - and to the distal parts of the cranial sensory ganglia. Recent evidence suggests that despite their diversity, all placodes share a common developmental origin and a common molecular mechanism which initiates their formation. At the base of placode induction lies the specification of a unique "placode field", termed the preplacodal region and acquisition of this "preplacodal state" is required for ectodermal cells to undergo otic development. Here I review the molecular mechanisms that sequentially subdivide the ectoderm to give rise to the placode territory.

Keywords:

BMP, ear, ectoderm, epibranchial, eye, FGF, olfactory epithelium, sensory placodes, Wnt

*Corresponding author e-mail: andrea.streit@kcl.ac.uk