Fig. 5. Cortical cells entering the GE in ngn2^lacZ/ngn2^lacZ mice acquire a ventral identity. (A-D) The cortico-striatal border in sections of the telencephalon from E14 ngn2^lacZ/ngn2^lacZ mice stained for ß-gal (blue) and hybridized with the probes indicated in the panel (purple ring). Sections are oriented with the cortex to the left and the GE to the right. Double-positive cells are indicated by arrowheads, ß-galactosidase-positive cells negative for the respective transcripts are marked by an arrow. Note that ectopic cells lose expression of cortical genes (lacZ in the ngn2 locus in A and Math2 in B), while they maintain (C) or acquire (D) expression of ventral genes such as Mash1 or Dlx5, respectively.