Figure 9
From: Tissue interactions in the developing chick diencephalon
Schematic model for ZLI establishment. Morphogenesis of the Lfng-negative wedge and Shh expression in the definitive ZLI are positively regulated by planar signals from the adjacent Lfng-positive areas (pro-Pth, Irx3-negative; pro-Th, Irx3-positive). CYP1B1 is expressed in the dorsal diencephalon and generates RA that inhibits Shh expression in the ZLI.