Figure 6.

Patterning defects in Gsh2 mutants and Gsh2/Tlx double mutants. A, At E12.5, NKX6.2 is expressed in the sulcus between the LGE and MGE. B, In Gsh2 mutants, a number of scattered cells expressing NKX6.2 ectopically are detected in the ventral most part of the LGE. Note also that the size of the mutant LGE is smaller than the wild-type LGE. C, In the Gsh2/Tlx double mutants, as in the Tlx mutants (Fig. 2B), NKX6.2 is ectopically expressed in the ventral half of the LGE. D, High PAX6 expression normally wraps around the pallio-LGE angle and stops in the dorsalmost portion of the LGE. In addition, a stream of PAX6-positive cells emanates from the ventralmost region of the PAX6 VZ expression domain down to the mantle zone (arrows). E, In Gsh2 mutants, PAX6 is ectopically expressed in the dorsal half of the LGE. Interestingly, the number of PAX6-positive cells in the mantle zone (arrows) is significantly reduced in these mutants. F, PAX6 is ectopically expressed also in the dorsal half of the Gsh2/Tlx double-mutant LGE. Surprisingly, in the Gsh2/Tlx double mutants, there appears to be a considerable number of PAX6-positive cells in the mantle zone (arrows). Note also that the ectopic expression of PAX6 and NKX6.2 in the double-mutant LGE leaves only a small domain of the ventral LGE correctly patterned (C, F). G, NKX6.2 expression at E14.5 in the wild-type telencephalon. H, Scattered cells throughout the E14.5 Gsh2 mutant LGE, which is significantly reduced in size, express NKX6.2 ectopically (inset). I, Interestingly, in the Gsh2/Tlx double mutant, NKX6.2 is extopically expressed at high levels throughout the LGE VZ up to the LGE-pallium angle. J, PAX6 is expressed in the pallium at E14.5. K, In Gsh2 mutants, a recovery is occurring by E14.5, and PAX6 expression is primarily normalized. L, This recovery also occurs in Gsh2/Tlx double mutants. Note that the expression domains of PAX6 and NKX6.2 nearly abut in the double mutants. (I, L). KO, Knockout; Stm, striatum.