Fig. 9. A model for the guidance of cortical projections in Nkx2-1 mutant mice. (A,B) The paths followed by pyramidal tract (blue), corticothalamic (pink), thalamocortical (purple) and dopaminergic mesotelencephalic (green) axons in wild-type (A) and Nkx2-1 mutant mice (B). The broken lines indicate the territories patterned by Nkx2-1 function. (C-F) The expression of Slit genes in the ventricular zone of the subpallium in wild-type (C) and Nkx2-1 mutant mice (E), and the hypothesized consequences of their function on the guidance of layer 5 cortical axons in wild-type (D) and Nkx2-1 mutant mice (F). Blue positive signs indicate a permissive territory, whereas negative signs and red hatching denote a non-permissive territory. a/b, alar/basal boundary; AEP, anterior entopeduncular region; Chr, chiasmatic region; Chr*, mutant chiasmatic region; cp, cerebral peduncle; DT, dorsal thalamus; ET, eminentia thalami; GP, globus pallidus; H, hippocampus; Hb, hindbrain; Hyp, hypothalamus; Hyp*, mutant hypothalamus; ic, internal capsule; M, mesencephalon; NCx, neocortex; POa, preoptic area; PrH, peduncular region of the hypothalamus; p/sp, pallial/subpallial boundary; PT, pretectum; ob, olfactory bulb; os, optic stalk; Str, striatum; Str*, mutant striatum; V, layer 5 cortical neurons; VI, layer 6 cortical neurons; VT, ventral thalamus.