Fig. 7. Partial rescue of the dentate gyrus in Emx2 mutant hippocampus. (A-I) Coronal sections through the hippocampus of E18.5 wild-type mice (A,D,G), Emx2 homozygote mice (B,E,H) and Emx2 homozygotes electroporated at E9.5 with sFGFR3c (C,F,I). (D-F) High-power micrographs of a different set of brains from those in (A-C). (A,D,G) Prox1 expression reveals the developing V-shaped DG in the hippocampus (A,D, arrow in A); EphB1 expression marks the distal end of the hippocampus, including the DG (G, arrow). (B,E,H) Emx2 homozygote mutants show no (B, arrow) or only tiny patches of (E) Prox1-expressing cells in the region of the presumptive DG, and greatly reduced EphB1 expression (arrow in H). (C,F,I) When excess FGF8 is reduced in Emx2 mutant brains, the DG expands, forming a dense band not unlike the ventral DG blade (C, arrow, F). Distal EphB1 expression is also partially restored (arrow, I). Scale bar: 0.75 mm for A-C,G-I; 0.125 mm for D-F.