Fig. 2. E11.5 coronal sections through wild-type (A-F) and Id4^-/- (A'-F') telencephalon. Wnt3a, Dbx1, Emx1 and Tbr2 expression in LP and VP progenitor zones appears normal (A-D'). (A-B') The limits of the Wnt3a and Dbx1 expression domains are indicated by the arrowheads. (C,C') Arrowheads indicate mantle expression of Emx1 in the lateral pallium. (D') Arrowhead indicates ectopic Tbr2-expressing cells in the VZ; arrow points to the increased number of Tbr2-expressing postmitotic cells in the dorsomedial mantle of the Id4^-/- animal. (E) Endogenous Id2 expression shows a ventral-to-dorsal gradient of expression and is undetectable between the arrowheads. (E') The boundaries of the reduced Id2-negative region in the Id4^-/- brain is indicated by arrowheads. (F) Id4 expression is uniformly high in all cortical areas. (F') GFP expression from the Id4 locus is detectable in the Id4^-/- brain (arrowhead). LGE, lateral ganglionic eminence; VP, ventral pallium; LP, lateral pallium; DP, dorsal pallium; MP, medial pallium; ctx, neocortex; LV, lateral ventricle.