Fig. 8. Normal thalamocortical projections with the rostral neocortex of `severe' Fgf8neo/neo newborns. In situ hybridization on sagittal sections (A-D) and DiI/DiA axonal tracing (E-L) were performed on the two hemispheres of one wild-type newborn (A,C,E,G,I,K) and one `severe' Fgf8neo/neo newborn lacking olfactory bulbs (B,D,F,H,J,L). (A-D) The superficial Cdh8 rostral expression (arrowhead in A) is absent in the rostral neocortex of the Fgf8neo/neo, as seen in a high-magnification view of the rostral neocortex (inset). In the same Fgf8neo/neo brain, the anterior limit of high Cdh6 expression moves into the most rostral and medial neocortex (arrowheads in C and D). (E,F) Lateral views show that DiI and DiA crystals (red and green arrowheads) were placed in the frontal (Fr) and parietal (Par) neocortices and into the parietal and frontal neocortex of the wild-type and Fgf8neo/neo brain, respectively (E,F). Approximate levels of the coronal sections presented in G,I,K and H,J,L are indicated by white lines. (G-J) Dark field pictures of coronal sections showing the position of the dye crystals (red and green arrowheads) in the frontal (G,H) and parietal (I,J) neocortices. Note that DiI and DiA crystals have inverted positions in wild-type and Fgf8neo/neo newborns. (K,L) Coronal sections through the dorsal thalamus, counterstained with Hoechst, show very similar retrograde labeling in the wild type and Fgf8neo/neo brain (arrowheads indicate the fasciculus retroflexus. Ncx, neocortex; OB, olfactory bulb.

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