Fig. 3. Alterations of the early thalamocortical projections in Pax6^-/- mice. (A,B) After dorsal thalamic (dt) DiI placements in both hemispheres at E15.5, TCAs were observed extending through the internal capsule (A), reaching the intermediate zone of the dorsal cortex (ctx) (arrow in B). (C,D) Two coronal sections stained for ß-galactosidase in an E14.5 Pax6^-/- mouse. Note the altered staining in ventral and lateral telencephalic areas compared with heterozygous brains shown in Fig.2A-C. (E,F) Dorsal thalamic DiI crystal placement in the Pax6^-/- brains (asterisk in E) showing that the ventrolateral hypothalamus (ht) was invaded by TCAs (E; arrowheads in F). (G) High power image of the box indicated in F. TCAs were observed crossing to the contralateral ventral hypothalamus (double arrowheads in G). (H) Backlabelled cells were also observed in abnormal locations in the hypothalamus (arrows in H). (I) Dorsal thalamic DiI crystal placement revealed few backlabelled cells within the internal capsule. (J) High-power image from the region indicated with the box in I (arrows indicate labelled cells). (K,L) By E18.5, TCAs in the Pax6^-/- emerged abnormally from the base of the ventral telencephalon (double arrowheads). GE, ganglionic eminences; pa, pallium; LGE, lateral ganglionic eminence; LV, lateral ventricle; PSPB, pallial/subpallial boundary. Scale bars: 400 µm in A,E; 100 µm in B,G,H,I,K,L; 200 µm in C,D,F; 20 µm in J.