Fig. 5. Ganglionic eminence-specific late marker gene expression in both forebrain and midbrain/hindbrain neural stem cell colonies. Neural stem cell colonies derived from E14.5 zfdlx4/dlx6lacZ transgenic mice were co-cultured with E14.5 CD1 tissues. (A,B) Sphere colonies derived from cortex, ganglionic eminence (GE) or midbrain/rostral hindbrain (MB/rHB) were placed (A, dotted areas) on the GE of host in the CD1 coronal slices. After 5 days in vitro (B), although some distortion of the tissue was seen, robust transgene expression (blue arrow pointing to blue staining) could be observed only when sphere colonies were placed in the region of the ventral forebrain. (C) Higher magnification of the boxed area in B showing transgene expression. (D,E) Transgene expression was not induced in cortical, GE and MB/rHB colonies (originally located in dotted areas) when placed on the germinal layer of CD1 cortical tissue (D) or midbrain tissue (E) after 5 days in vitro. (F-H) Neurosphere colonies were placed on the isolated VZ (F, dotted areas on top slice) from E14.5 CD1 coronal slice and on the remaining GE in the slice (F, dotted areas on bottom slice). Transgene expression was not observed in the neural stem cell colonies (0/4 co-cultures) on isolated VZ tissue (G, arrowhead), but was expressed (4/4 co-cultures) in the neural stem cell colonies on the remaining GE tissue, composed of subventricular zone and mantle zone (H, blue arrow pointing to blue staining). Data are representative of at least 3 separate experiments in each case. Scale bar, 1.74 mm (A), 1.42 mm (B), 0.39 mm (C), 12.1 mm (D,E), 2.2 mm (F), or 1.2 mm (G,H).