Comparative analysis of Otx2, Gbx2, Pax2, Fgf8 and Wnt1 gene expressions during the formation of the chick midbrain/hindbrain domain

The patterns of the Gbx2, Pax2, Wnt1, and Fgf8 gene expression were analyze d in the chick with respect to the caudal limit of the Otx2 anterior domain , taken as a landmark of the midbrain/hindbrain (MH) boundary. The Gbx2 ant erior boundary is always concomitant with the Otx2 posterior boundary. The ring of Wnt1 expression is included within the Otx2 domain and Fgf8 transcr ipts included within the Gbx2 neuroepithelium. Pax2 expression is centred o n the MH boundary with a double decreasing gradient. We propose a new nomen clature to differentiate the vesicles and constrictions observed in the avi an MH domain at stage HH10 and HH20, based on the localization of the Gbx2/ Otx2 common boundary. (C) 1999 Elsevier Science Ireland Ltd. All rights res erved.