THE LATERAL GANGLIONIC EMINENCE IS THE ORIGIN OF CELLS COMMITTED TO STRIATAL PHENOTYPES - NEURAL TRANSPLANTATION AND DEVELOPMENTAL EVIDENCE

In order to determine whether the lateral ganglionic eminence (LGE) of the fetal telencephalon is the primary source of striatal precursors in striatal transplants and tissue cultures, cells derived exclusively from the LGE of fetal rat brains were transplanted into the quinolini c-acid-lesioned striatum of adult rats. After 2-3 months they produced grafts that were almost entirely AChE-positive as well as DARPP-32-, TH-, and calbindin-immunoreactive. The grafts were integrated into the host striatum so that host corticofugal fiber tracts interdigitated w ith graft tissues similar to the way they penetrate the gray matter of the normal striatum. Fast Blue dye injected into the ipsilateral glob us pallidus of LGE grafted produced retrogradely labeled neurons withi n the grafts, but Fluorogold dye injected into the ipsilateral substan tia nigra did not. In a separate experiment using DARPP-32-immunohisto chemstry as a striatal marker, fetal (E16) and neonatal (P2) rat brain s showed DARPP-32 immunoreactivity in the LGE but not in the adjacent medial ganglionic eminence (MGE). In summary, both fetal LGE cells and LGE grafts express specific striatal markers, and LGE grafts integrat e into the host striatum and innervate the major striatal efferent tar get within the host brain. These data suggest that the LGE is the orig in of cells committed to striatal phenotypes in the developing brain.