Fig. 5. Immunolabeling for L1 (A-L) and TAG1 (M-P) reveals defects in TCAs and CFA in the Pax6^-/-brains. (A,B) At E14.5 in wild-type brains, TCAs and CFA are both immunoreactive for L1 through the internal capsule into the intermediate zone of the cortex (ctx). (C,D) At E14.5 in the Pax6^-/-, TCAs (arrows) and CFA (arrowheads) are both aberrant, thalamic axons fail to extend towards the cortex and CFA fail to turn towards the internal capsule. (E,I) At E18.5, L1-positive fibres are observed crossing the PSPB in wild-type brains (arrows in I). (F,G,J,K) L1 immunoreactive fibre trajectories follow aberrant pathways and cannot cross the PSPB (arrows) in the Pax6^-/-. A cellular mass (asterisk) fills the lateral ventricle (LV). (H,L) Abnormal fasciculation of L1 immunopositive axons along the dorsal cortex of the Pax6^-/-. (M,N) At E14.5 wild-type brains, TAG1 immunoreactive CFA extend to the PSPB (arrows). (O,P) TAG1 immunoreactive CFA in the Pax6^-/- cortex (arrowheads) do not cross the PSPB. GE, ganglionic eminences; hp, hippocampus. Scale bars: 100 µm.