GSH2 expression in the E12.5 and E14.5 Tlx mutant LGE. A, C, GSH2 is normally expressed in a gradient throughout the LGE VZ; the highest expression is detected in the most dorsal part of the LGE (indicated by arrows), and the lowest expression is detected in the sulcus between the LGE and MGE. B, D, In Tlx mutants, the level of GSH2 expression is more uniform; high levels of GSH2 are detected in a broader region of the LGE VZ (indicated by arrows). In addition, the “thickness” of the expression domain in the VZ is reduced, indicating that the number of precursor cells expressing GSH2 along the ventricular-pial axis is reduced. Stm, Striatum; KO, knock-out.