Fig. 1. Expression of NKX2-1 in the developing forebrain. (A) Sagittal section through the brain of an E12.5 embryo showing the expression of NKX2-1 in the basal telencephalic and hypothalamic primordia. The broken lines indicate the approximate levels of the sections shown in (B,C). (B,C) Coronal sections that highlight the basal telencephalon and rostral diencephalon (B) and mid-diencephalon (C) of an E12.5 embryo showing expression of NKX2-1. (D-G) High-magnification images of coronal sections through the telencephalon (D,E) and diencephalon (F,G) of an E14.5 embryo showing expression of NKX2-1 at the level of the internal capsule (D) and close to cerebral peduncle at the level of the hypothalamus (F). (E,G) DAPI counterstained images of the sections showed in (D,F). The insets in E,G indicate the level from where the images were taken. (H) Schematic drawing showing the relationship between the paths followed by pyramidal tract (blue), corticothalamic (pink) and thalamocortical (purple) axons in relation to the territories patterned by Nkx2-1 (light pink). a/b, alar/basal boundary; AEP, anterior entopeduncular region; Chr, chiasmatic region; cp, cerebral peduncle; DT, dorsal thalamus; ET, eminentia thalami; GP, globus pallidus; H, hippocampus; Hb, hindbrain; Hyp, hypothalamus; ic, internal capsule; LGE, lateral ganglionic eminence; M, mesencephalon; MGE, medial ganglionic eminence; NCx, neocortex; ob, olfactory bulb; os, optic stalk; POa, preoptic area; PrH, peduncular region of the hypothalamus; p/sp, pallial/subpallial boundary; PT, pretectum; Str, striatum; V, layer 5 cortical neurons; VI, layer 6 cortical neurons; VT, ventral thalamus. Scale bar: 200 µm in A-C; 100 µm in D-G.