In support of this, double homozygous mutants for Pax6 and Gsh2 exhibit significant improvements in both cortical and striatal development compared with their respective single mutants. The remaining neuroblasts, by all markers tested, appear to have acquired a dorsal fate. The telencephalon and diencephalon, which comprise the vertebrate forebrain, arise from the anterior-most region of the neuraxis. The telencephalon is subdivided into the pallial and subpallial domains. The pallium gives rise to dorsal structures, including the cerebral cortex, while the subpallium gives rise to ventral structures, including the globus pallidus and the striatum, which in combination form the majority of the basal ganglia.
Homeobox genes are important for the proper patterning of the mammalian telencephalon.
Expression of Gsh2 is restricted in the mouse forebrain to the ventral domain. At E9.5, Gsh2 mRNA expression is found the ventrolateral telencephalon, a region from where the LGE will putatively emerge. Interestingly, at E9.5, although a few GSH2-expressing cells appear to intermingle with those expressing NKX2.1, GSH2 and NKX2.1 are predominantly expressed in separate domains. By E10.5, coincident with the emergence of the MGE, GSH2 expression extends into the MGE and overlaps with NKX2.1 expression. By E12.5, Gsh2 is expressed in the MGE, LGE and septum.