forebrain or migrated dorsally after induction in the ventral domain (Fertuzinhos et al., 2009). By performing immunocytochemical analyses in early stage human embryos (Carnegie Stage 15, ~ 38 days post conception), we observed restriction of NKX2.1 expression to the ventral forebrain (Figure 2B–E) comparable to the developing mouse CNS. The NKX2.1 domain in the human embryonic ventral forebrain was further subdivided into an OLIG2+ ganglionic eminence and an OLIG2-negative preoptic area anlage (Figure 2C,D).
