Figure 2.

Neural stem cells are abundant in the MGE OSVZ. (a) Progenitor markers of the ventral forebrain (SOX2, OLIG2, ASCL1, Ki67) labeled the human MGE (marked by NKX2-1) and CGE (marked by strong COUP-TFII) more strongly than the LGE. PCW12 frontal sections are from an intermediate location on the rostral-caudal axis. Th, thalamus. Scale bars represent 1 mm. (b) The MGE OSVZ had an abundance of cells expressing the same markers (OLIG2⁺, ASCL1⁻, DLX2⁻) as undifferentiated radial glia in the ventricular zone. Shown are representative fields of images quantified in c. (c,d) OSVZ progenitor cells in the MGE were less differentiated than those in the CGE and LGE. OLIG2⁺ cells were less likely to express markers of neuronal commitment, and ASCL1⁺ and Ki67⁺ cells were less likely to express DLX2 in the MGE. The difference in the degree of differentiation among OLIG2⁺ cells also reached significance when comparing CGE and LGE (t₂₉ = 4.37, P = 0.0002). The CGE was only measured at PCW12, as it is not well developed at PCW10 and our sample of PCW14 brain tissue lacked the CGE and other caudoventral structures. Error bars represent s.e.m.; t test P values are indicated. (e) SOX5, expressed in radial glia of the ganglionic eminence ventricular zone, was abundantly expressed in OSVZ progenitors in the MGE. (f) OLIG2⁺ cells in the human MGE OSVZ generally did not express NKX2-2, an oligodendroglial lineage marker. The arrowhead marks a rare exception. In the cortex, most or all of the sparse OLIG2⁺ cells throughout the OSVZ and intermediate zone expressed NKX2-2.