Fig. 1.

Most chicken MGE cells migrated medially through the neocortical SVZ/IZ, the same as mouse MGE cells did, but they failed to enter the CP/MZ. (A and B) Distribution of GFP-expressing mouse MGE cells (green) and mCherry-expressing chicken MGE cells (magenta) in coronal sections through the middle level along the rostrocaudal axis of the host forebrain at E16.5 (A) and P7 (B). Transplantation with chicken MGE cells was performed as illustrated in Fig. S2. (C and D) Enlarged views of the boxed regions in A and B. (E) Quantification of the distribution of GFP-expressing mouse MGE cells and mCherry-expressing chicken MGE cells in embryonic and neonatal neocortical layers. The percentages of GFP and mCherry cells in each layer were analyzed (mean ± SEM) at E15.5 (n = 3 brains, 114 GFP cells), E16.5 (n = 5 brains, 311 GFP and 194 mCherry cells), E18.5 (n = 4 brains, 566 GFP and 102 mCherry cells), P2 (n = 5 brains, 910 GFP and 233 mCherry cells), and P7 (n = 4 brains, 300 GFP and 201 mCherry cells). Because only a few mCherry cells were found in the neocortex at E15.5, they were excluded from the analysis. At E15.5 and E16.5, the neocortical wall was subdivided into seven layers: MZ, upper CP (U-CP), lower CP (L-CP), upper IZ (U-IZ), lower IZ (L-IZ), SVZ, and VZ. Because the border between the IZ and SVZ was indistinct, the SVZ was defined as a zone occupying one-quarter of the thickness of the VZ. The subplate has been omitted for the sake of simplicity. At both E18.5 and P2, the SVZ and VZ were combined into one zone, the SVZ/VZ. At P7, the U-IZ, L-IZ, and SVZ/VZ were combined into one zone as the white matter (WM), and layer 1, layers 2–4, and layers 5 and 6 have been represented as MZ, U-CP, and L-CP, respectively, in the graph to simplify comparisons. GE, ganglionic eminence; Hip, hippocampus; L1-6, layers 1–6; L, lateral; D, dorsal. (Scale bars: A, 500 μm; B, 1 mm; C and D, 200 μm.)