Wnt1 signal determines the patterning of the diencephalic dorso-ventral axis.

The diencephalon is a complex brain area that derives from the caudal region of the prosencephalon. This structure is divided into four longitudinal neuroepithelial zones: roof, alar, basal and floor plates, which constitute its dorso-ventral (DV) columnar domains. Morphogenetic differences between alar and basal plates in the prosencephalon and mesencephalon contribute to the characteristic expansion of alar plate derivatives in the brain and the formation of the cephalic flexure.

Wnt signal specifies the intrathalamic limit and its organizer properties by regulating Shh induction in the alar plate.

The structural complexity of the brain depends on precise molecular and cellular regulatory mechanisms orchestrated by regional morphogenetic organizers. The thalamic organizer is the zona limitans intrathalamica (ZLI), a transverse linear neuroepithelial domain in the alar plate of the diencephalon. Because of its production of Sonic hedgehog, ZLI acts as a morphogenetic signaling center.