fezl expression in the developing forebrain demarcates the prospective telencephalon, hypothalamus and prethalamus. (A-L) Analysis of gene expression. Arrow in F indicates the prospective diencephalon; arrowhead in F indicates the telencephalon; arrowhead in I indicates wnt1 expression; arrow in J and arrowhead in K,L indicate the presumptive ZLI; arrowhead in J indicates the MHB. All are dorsal views except C,D,K,L, which are lateral views. Stages and marker identities are indicated in each panel. di, prospective diencephalon; e, eye region; hy, hypothalamus; hb, hindbrain; mhb, midhindbrain boundary; pd, posterior diencephalon; przli, presumptive ZLI; pt, prethalamus; tel, telencephalon; epi, epiboly; som, somite.