Figure 8.

Transplanted progenitors from the E14.5 CGE give rise to calretinin-expressing cells. A, The region of CGE that was dissected from a 300-μm-thick coronal section at E14.5. This region is dorsal to the Nkx2.1-expressing domain (Nery et al., 2002). Many of the GFP plus CGE donor cells (B) colabel for calretinin (C). These colabeled neurons do not also label for reelin (D) (reelin triple labeled with GFP and calretinin in a total of 6 of 201 cells from 3 separate experiments). Graph in E shows that CGE donors generate calretinin-expressing (Calr) cells primarily at E14.5 and that relatively few parvalbumin (Parv)- or somatostatin (Somt)-expressing neurons are generated by these transplants. F, Many of the calretinin+ donor neurons from CGE were generated by progenitors that proliferated after transplantation. The graph shows the percentage of GFP+–calretinin+ neurons from the E14.5 CGE that proliferated (triple labeled with BrdU) during the first, second, or third DIV. The rise in triple-labeled cells between the first and second DIV results from the addition of FGF2 to the medium at the start of 2DIV as indicated by arrowheads. The graph in G shows BrdU incorporation by GFP+ donor neurons from the MGE at E12.5 and from the MGE, LGE, or CGE at E14.5. Despite high levels of proliferation during the first day in vitro for MGE donors at E12.5 and modest initial levels of proliferation for MGE or LGE donors at E14.5, only the CGE donors give rise to large numbers of calretinin+ neurons. Ctx, Cortex, Th, thalamus; Hyp, hypothalamus; Calr, calretinin; Rln, reelin. Scale bars: A, 500 μm; B–D, 50 μm.