Central Nervous System Ventralization

Ventralization, a major patterning process in developing vertebrate central nervous systems, depends on Sonic hedgehog (Shh) as a main signaling morphogen.

As expected, this gene is expressed in the zebrafish brain in ventrally located floor plate cells of spinal cord and brainstem floor plate. Further, a ventral telencephalic Shh domain is newly identified in zebrafish known to be important for correct basal ganglia development in land-vertebrates (e.g. mammals and birds).

Also, posterior forebrain zebrafish dopamine cells projecting into the basal ganglia derive directly from Shh expressing cells (as do mammalian substantia nigra/ventral tegmental cells affected in Parkinson’s disease in humans).