Figure 4

Disruption of thalamic axons in E14.5 Pax6 conditional knockouts. Coronal vibratome sections (200 μm) for control and conditional knockout (cKO) embryos injected with DiI in the dorsal thalamus: (A, C) bisbenzimide stained sections from (A) control and (C) cKO; (B-B") DiI labeling from control at increasing magnifications; (D-F) serial sections from cKO with central section (E) shown at increasing magnifications in (E', E"). In control embryos, the dense bundle of thalamic axons traversing the diencephalon turns into the ventral telencephalon and travels through the internal capsule (IC). In cKOs, although a dense normal-appearing bundle of thalamic axons traverses the diencephalon (E), much of the bundle appears to end at the diencephalic-telencephalic border (bracket in (E')), fewer thalamic axons traverse the internal capsule and some of those axons that do penetrate the internal capsule exit it ventrally (at the position of the white arrowhead in (C); labeled axons exiting ventrally are indicated by white arrowheads in (E-E")). The white arrow in (C) indicates the diencephalic-telencephalic border. Scale bars: 50 μm.