Figure 5

Disruption of thalamic axons in E16.5 Pax6 conditional knockouts. Coronal vibratome sections for control and conditional knockout (cKO) embryos injected with DiI in the dorsal thalamus. (A, B) Bisbenzimide stained sections show narrowing of the internal capsule between the white arrowheads. (A'-B") Corresponding DiI labeled sections; boxed areas in (A', B') are shown in (A", B"), respectively. In cKOs, many thalamic axons do not turn across the diencephalic-telencephalic border (DTB) but descend ventrally towards the hypothalamus. This aberrant tract corresponds to a cell-free spur seen in bisbenzimide-stained sections near the start of the internal capsule (red arrowheads in (B)). (C-F) High magnification optical sections from around the boxed area in (B"): many aberrant axons descend directly ventrally (white arrowheads) while a few loop out medially (yellow arrowheads) or project laterally into ventral telencephalon (green arrowheads). Scale bars: 50 μm.