Fig. 3. E12.5Pax6−/−↔Pax6+/+
chimeras show an autonomous requirement for Pax6 in the dorsal thalamus but not in the medial part of the ventral telencephalon. a, d, Low magnification of horizontal sections of chimeras like those used to examine the contribution of cells to the medial part of the ventral telencephalon (a) and the dorsal thalamus (d) (red boxes indicate location and orientation of higher magnification fields). b,c, e–g, High magnification of portions of typical fields used for quantification:c, f, g, inPax6−/−,Tg+
↔Pax6+/+
chimeras; b,e, inPax6+/+,Tg+↔Pax6+/+
chimeras. In these images medial is to the right, and rostral is at the top. The Tg signals appear asbrown spots in the nuclei (here stainedblue). In the medial part of the ventral telencephalon, bothPax6+/+,Tg+
(b) andPax6−/−,Tg+
(c) cells intermingle equally well withPax6+/+, Tg−
cells. In the dorsal thalamus, althoughPax6+/+,Tg+
(e) cells are well mixed with thePax6+/+,Tg−
cells,Pax6−/−,Tg+
(f, g) cells do not intermingle with their wild-type counterparts and instead form stripes highly enriched for Pax6−/−
cells (red arrows in f, g) separated by regions consisting almost exclusively ofPax6+/+
cells (red arrowheads in f). In some cases the larger congregations ofPax6−/−
cells seem to have caused the ventricular surface of the dorsal thalamus to buckle inward (red arrow in g).e, Eye; cc, cerebral cortex;dt, dorsal thalamus; vtel, ventral telencephalon. Scale bars: a, d, 500 μm; b, c,e–g, 50 μm.