The development of the rat striatum was investigated using a combination of two histochemically distinguishable retrovirus vectors. Using this method, it was possible to identify clonal boundaries within the embryonic striatum and thus determine patterns of proliferation, migration, and some lineal relationships. Several novel aspects of striatal histogenesis were discovered. Striatal progenitor cells do not exhibit a stem cell pattern of division between embryonic day 15 (E15) and E19; a progenitor-progeny relationship appears to exist for ventricular zone and subventricular zone (SVZ) cells; striatal progenitors produce a variety of clone types; some SVZ cells migrate radially, and some migrate tangentially within the SVZ; and radial glia and presumptive neurons can occur in the same clone.