 These experiments demonstrated the ZLI as a cell-lineage restriction boundary.Not only a boundary, the ZLI is also a compartment with separate cell lineage restriction boundaries both anterior and posterior of a section of "shh" expression.The importance of the ZLI was once more confirmed by ectopic expression of "shh" in other regions of the forebrain, known as the prosencephalon during development (both the telencephalon and diencephalon), inducing a ZLI-like region that induces thalamic fate.