Fig. 2. Migratory routes of cortical interneurons along the TAG-1 immunopositive corticofugal fibers. CP, cortical plate; IC, internal capsule; IZ, intermediate zone; LGE, lateral ganglionic eminence; MZ, marginal zone. The broken line demarcates the ventricle. (A) Tangential migration of neurons to different layers of the developing cerebral cortex in cortical slice cultures of an E16 rat embryo, after placement of DiI into the ganglionic eminence. (B) Double immunohistochemistry against GABA (red) and TAG-1 (green) in coronal sections of E12.5 mouse cortex, shows the juxtaposition of TAG-1 immunoreactive fibers and GABAergic cells at the IC. (C,D) DiI tracing for tangentially migrating neurons (red) and immunohistochemistry against TAG-1 (green), in slice cultures of E15 (C) or E16 (D) rat cortex. (C) Tangentially migrating neurons in close association with TAG-1 immunoreactive fibers in the IZ. (D) DiI-labeled migrating neuron in the CP, with the leading process oriented perpendicular to the pial surface and in close apposition to the radially arranged bundles of the TAG-1 immunopositive axons. (E,F) Double immunohistochemistry against GABA (red) and TAG-1 (green), in slice cultures of E15 (E) or E16 (F) rat cortex. (E) Tangentially oriented GABAergic neurons are found dispersed between TAG-1-labeled axons, in the IZ. (F) GABAergic neurons and fibers in the IZ, CP and MZ. In IZ and MZ, cells show tangential orientation, whereas, in the CP, they tend to be radially organized in apposition to the TAG-1 positive axons. (G) Double immunohistochemistry with RC2 antibody (green) and anti-GABA (red) in slice cultures of E14.5 mouse cortex. Arrows point to migrating neurons in the CP with the leading process perpendicular to the pial surface and in close apposition to the radial glial fibers. (H) Double immunohistochemistry with RC2 antibody (green) and anti-TAG-1 (red) in coronal sections of E14.5 mouse cortex. TAG-1 and RC2 are not co-localized in the CP. Inset: higher magnification of the red box. Scale bars: 100 µm in A,B; 40 µm in C,F; 25 µm in G,H; 10 µm in inset.
