Expression of Ngn1, Ngn2, Cash1, Gsh2 and Sfrp1 in the developing chick telencephalon

Patterning of the chick telencephalon has been debated, especially in regard to a ventral (subpallial) or dorsal (pallial) nature of the dorsal ventricular ridge (DVR). Here we report the expression patterns of chick homologues of molecules known to be involved in telencephalic patterning in other vertebrate species. We show here that the transcription factors Ngn1, Ngn2, Cash1, Gsh2 and the secreted frizzled related protein 1 (sfrp1), a wnt receptor, are expressed in characteristic telencephalic domains during chick development. At embryonic day 7 (E7) Ngn1 and Ngn2 are localized in the dorsal pallium and the DVR, similar to the region of Pax6 expression. In contrast, Gsh2 and Cash1 are restricted to the subpallium and some DVR cells. Interestingly Sfrp, a dorsoventral boundary marker in mouse telencephalon, is expressed between the DVR and subpallium. Gsh2 and Pax6 double-positive cells further characterize this boundary region in the developing chick telencephalon.