 This also indicates that other patterning cues are able to establish Fgf8 and Wnt signaling domains at the ZLI in the absence of Shh and Gli3.After differentiation of the progenitor cells (at a precise stage yet to be fully determined), the ZLI and its lineage restriction disappears, allowing cells to migrate across the former boundary and the dorsal and ventral thalami to merge into one functional unit, as shown by replication-incompetent retroviral experiments that marked cells and showed their migration throughout the diencephalon.After establishment of the ZLI, "shh" has been shown to induce expression of thalamic and prethalamic markers, "gbx2" and "dlx2"/ "nkx2.1", respectively.