Figure 6.
Transient accumulation of interneurons in the MZ. A, Enlarged view of the boxed region in B. GFP cells entered the cortex via the SVZ (arrowheads), not the MZ (asterisk). All sections were counterstained with DAPI (blue) to determine the cortical zones. B, The distribution of GFP cells in the ipsilateral E12Ge:E14 forebrain. The region sandwiched between the open arrowheads is the presumptive region where Gfp plasmids were extensively transfected. C–E, The distribution of GFP cells in E12Ge:E14 (C), E12Ge:E18.5 (D), and E12Ge:P2 (E) coronal sections. Dorsomedial is toward the right. F, Quantification of the zonal distribution of labeled cells in E12Ge:E14 (n = 273 cells, 49 sections, 4 brains), E12Ge:E15.5 (n = 222 cells, 31 sections, 3 brains), E12Ge:E18.5 (n = 659 cells, 23 sections, 3 brains), E12Ge:P2 (n = 174 cells, 33 sections, 3 brains), and E12Ge:P21 (n = 544 cells, 178 sections, 5 brains) cortices (average ± SEM). The abscissa indicates the proportion of labeled cells in each cortical zone. At E14–E15.5, the cortical wall was subdivided into eight zones: MZ, upper CP (u-CP), lower CP (l-CP), subplate (SP), upper intermediate zone (u-IZ), lower IZ (l-IZ), SVZ, and VZ. Because the border between the IZ and SVZ was obscure, the SVZ was defined as a zone with one-quarter thickness of the VZ. The SP was defined as a monolayer between the CP and the IZ. At both E18.5 and P2, SVZ and VZ were unified as one zone, SVZ/VZ. At P21, SP, IZ and SVZ/VZ were unified as one zone, white matter, whereas layers 1, 2–4, and 5/6 were represented as MZ, u-CP, and l-CP in the graph, respectively. These categories were made to simplify comparisons. G, Same as F, but for mCherry/GAD67-GFP double-labeled cells in E15Ge:E17.5 (n = 250 cells, 28 sections, 3 brains), E15Ge:P1 (n = 140 cells, 27 sections, 3 brains), and E15Ge:P7 (n = 164 cells, 24 sections, 3 brains) GAD67-GFP cortices. Scale bars: A, C–E, 100 μm; B, 500 μm.