Fig. 7. Expression of marker genes of early forebrain development in E10.5 embryos. (A,B) In-situ hybridization (ISH) of frontal head aspects (upper panel) and coronal forebrain sections (lower panel) demonstrate reduced signals for Olig2 (A) and Nkx2.1 (B) in the AEP (arrowheads) but not in the diencephalon of megalin^–/– embryos. (C) Expression of Dlx2 is lost in the ventral telencephalon (arrowheads) and significantly reduced in the ventral thalamus region of the diencephalon (asterisks) of megalin^–/– embryos as shown by whole-mount ISH. (D) Immunohistology of coronal E10.5 forebrain sections indicate lack of TuJ1 expression in the ventral (arrowheads), but not in the dorsal, telencephalic region of megalin^–/– compared with control embryos. (E-H) Using whole-mount ISH, no differences can be seen in the expression patterns of Ptch1 (ventral neural tube, including tel-, di- and mesencephalon) (E), Hnf3b (ventral neural tube, including di- and mesencephalon) (F), or Wnt1 (roof of di- and mesencephalon, isthmus) (G), whereas expression of Pax6 extends from the dorsal into the ventral neural tube of receptor-deficient embryos (H, arrowhead). Also, most knockouts lack the Pax6 signal in the optic vesicle. di, diencephalon; is, isthmus; me, mesencephalon; ov, optic vesicle; te, telencephalon.