Fig. 1. dLGN axons are misrouted in the amygdalar region of Ebf1^-/- embryos. DiI axonal tracing in controls (left) and Ebf1^-/- mutant embryos (right). (A-D) Coronal hemisections of E16 brains in which a DiI crystal was placed in the lateral part of the dorsal thalamus (stars in A,B). In controls, DiI-labeled thalamic axons exit the dorsal thalamus and enter the internal capsule (open arrowhead in A). More rostrally, thalamic axons travel through the striatum and reach the neocortical intermediate zone (open arrowheads in C). In homozygous Ebf1 mutants, at caudal levels, some thalamic axons grow ectopically into the amygdalar region (white arrowhead in B) and very few axons leave this aberrant tract to navigate through the striatum and towards the neocortex (open arrowhead in B). However, rostrally, Ebf1 mutant thalamic axons are normally positioned in the striatum and neocortex (open arrowheads in D). (E,F) Coronal hemisections of E16.5 brains where a DiI crystal was placed in the amygdalar region (stars in E,F). The stria terminalis is stained in both controls and Ebf1^-/- mutant embryos (open arrowhead in E,F). However, in Ebf1^-/- embryos DiI labeling of the abnormal amygdalar tract (white arrowhead) retrogradely labels cells in a thalamic nucleus that has the shape and position of the dLGN (arrow). Am, amygdala; dTH, dorsal thalamus; Ncx, neocortex; Str, striatum.