Supplementary Figure 9: Transcription factor patterning in the MGE ventricular zone.

a) At the interganglionic sulcus (asterisk), COUP-TFII is expressed in the same region of VZ where MGE fate determinants are downregulated, similar to the pattern in mouse (Nery et al., 2002). Sections from rostral-intermediate region of PCW12 GE. b) Going from ventral MGE to dorsal MGE, the VZ changes from containing mostly NKX2-1^high progenitor cells (box 1) to mostly NKX2-1^low cells (box 3), with the region between being a mixture of NKX2-1^high and NKX2-1^low cells (box 2). COUP-TFII is expressed infrequently in the MGE and in distinct cells from those that express NKX2-1. In the dorsalmost VZ near the interganglionic sulcus (asterisk), the regions of NKX2-1 and COUP-TFII expression overlap but the two factors are expressed in mutually exclusive cells (box 4). Thus, these COUP-TFII+ cells may actually be CGE-type progenitors. The few OSVZ cells that appear to be co-labeled are juxtaposed cells with overlapping signal. Section from intermediate rostral-caudal location of PCW12 MGE. c) The high-to-low ventral-dorsal gradient of NKX2-1 expression in the MGE VZ (outlined in right panel) is also observed in PCW10 tissue. The expression level of NKX2-1 in MGE progenitors may be related to the preferential production of parvalbumin⁺ or somatostatin⁺ cortical interneurons in the ventral or dorsal MGE, respectively. Section from intermediate rostral-caudal location. Cd, caudate; IC, internal capsule; Pu, putamen; Cx, cortex.