Figure 3

Disruption of thalamic axons in E12.5 Pax6 conditional knockouts. A rostral-to-caudal series of coronal 100 μm vibratome sections is shown for control and conditional knockout (cKO) embryos. (A-F) Bisbenzimide staining; (A', A"-F', F") corresponding low and high magnification views of DiI labeling from the dorsal thalamus (DT). Stars in (B', C', E') indicate the points of DiI crystal placement. Boxed areas in (A', D'), shown in (A", D"), respectively, demonstrate that retrogradely labeled neurons are present in ventral telencephalon (VTel) in both control and cKO embryos. In control embryos the axons from dorsal thalamus are oriented towards and intermingle neatly with the axons of ventral telencephalic neurons (white arrowheads in (B")); in cKOs, many thalamic axons are disorganized in their projection (white arrowheads in (E")); the white arrows in (B, E) indicate the centers of the regions shown in (B", E"). Both control and cKO embryos have retrogradely labeled cell bodies in the ventral thalamus (VT) (white arrowheads in (C", F")). Scale bars: 50 μm.