REGIONAL INCORPORATION AND SITE-SPECIFIC DIFFERENTIATION OF STRIATAL PRECURSORS TRANSPLANTED TO THE EMBRYONIC FOREBRAIN VENTRICLE

The developmental potential of neural progenitors derived from the E13 .5-E14 lateral or medial ganglionic eminences (LGE and MGE, respective ly) or the E12 ventral mesencephalon (VM) was examined in a cross-spec ies transplantation model. After injection into the E15 rat forebrain ventricle, mouse LGE progenitors (unlike those of the MGE or VM) were consistently integrated into the host striatum, expressing neurochemic al phenotypes and axonal projections characteristic of striatal projec tion neurons. Additionally, both LGE and MGE precursors displayed wide spread incorporation into distinct forebrain and midbrain structures, whereas the more caudally derived VM cells were largely confined to mi dbrain structures. These results suggest that many LGE precursors are positionally specified for striatal incorporation, while a portion als o possess greater potential reflected in more widespread integration f ollowing intraventricular injection.