Molecular characterization of progenitor cells in the embryonic POA. A–E, Coronal sections through the caudal telencephalon at E13.5 showing the expression of Nkx2-1 (A), Shh (B), Olig2 (C), Dbx1 (D), and Nkx6-2 (E) mRNA. Sections B–E are from the same brain and are adjacent to each other. The red dashed lines mark the ventricular zone, whereas the white arrowheads mark the limit between the MGE and the POA. GP, Globus pallidus; H, hippocampus; NCx, neocortex; PCx, piriform cortex; Str, striatum; Th, thalamus. Scale bars: A, 50 μm; B–E, 100 μm.