Primordia of the prethalamus and the thalamus are not affected in Wnt3/Wnt3a morphant embryos. Analysis of the fezf2 positive anterior forebrain area at 15 and 28 hpf reveals an expansion of the telencephalic domain (red brackets), however, the prethalamus (yellow brackets) is unaltered wnt3/wnt3a morphant embryos (A, B, G, H). Posteriorly analysis of the irx1b as well as the otx1l expression shows that the thalamic domain does not change significantly (yellow brackets), whereas, the midbrain territory shrinks in compound morphant embryos (red brackets, C-F; I-L). Notably, although both organizers - the MDO and MHB - disappeared in wnt3/wnt3a morphant embryos, expression of competence factors like fezf2 and irx1b are unaltered at 28 hpf, suggesting a specific function of Wnt3/Wnt3a in organizer formation. cFb, caudal forebrain, Mb, midbrain.