Formation of dorsal-ventral axis of the pallium derived from mouse embryonic stem cells.

The telencephalon is one of the most-elaborated tissues. A broad variety of cell types is produced by spatiotemporally regulated mechanisms and is involved, in different combinations, in subregional formation. The dorsal half of the telencephalon, the pallium or cerebral cortex, is subdivided along the dorsal-ventral (D-V) axis into the medial, dorsal, lateral, and ventral pallium (MP, DP, LP and VP, respectively). An in vitro differentiation system has been achieved using mouse embryonic stem cells, and major telencephalic neurons can be obtained in this way; however, in using the in vitro differentiation system, many telencephalic neuron subtypes remain undifferentiated, although some of them are related to neuronal diseases. In the current study, we found that inhibiting the TGFbeta signal was efficient for neural induction. A continuous arrangement of Emx1+/Pax6-, Emx1+/Pax6+, and Emx1-/Pax6+ cells was achieved in Foxg1+ neuroepithelia, corresponding approximately to cortical progenitors derived from MP, DP/LP, and VP, respectively. A small portion of Dbx1+ cells resided in the VP fraction. These findings suggested that the D-V axis of the pallium was recapitulated in the in vitro-derived pallium.