Fig. 2. Anterior overexpression of FGF8 causes prolonged downregulation of WNT expression in the hem, and a defective hippocampus. (A-L) Coronal sections of E15.5 brains processed for in situ hybridization. Medial is towards the left. Brains are electroporated with Ap (A-C,G-I) or Fgf8 (D-F,J-L) at E11.5. Each row illustrates three near-adjacent sections from the same brain. (A-C) A brain electroporated with Ap (transgene in B) shows normal expression of Wnt3a at the hem remnant (arrow, A), and a dense patch of Ka1 in the developing hippocampal CA3 field (arrow, C). A brain electroporated with Fgf8 (E) shows a little Wnt3a expression (D), and diffuse Ka1 expression in the hippocampus (asterisk, F). (G-L) Similarly a brain electroporated with Ap displays robust Wnt5a expression in the distal region of the hippocampus (G, asterisk), compared with very sparse and diffuse expression in a brain electroporated with Fgf8 (J, asterisk). Prox1 marks the developing DG in I, but not in L. Scale bar: 0.25 mm.