Fig. 4. Shh expression in wild-type and megalin^–/– embryos. (A,B) Whole-mount in-situ hybridization (ISH) in E9.5 wild type (A) and megalin-deficient embryos (B), demonstrating an identical expression pattern for Shh in floorplate and ventral prosencephalon. (C,D) Whole-mount ISH for Shh in E10.5 embryos, indicating expression in the ventral telencephalon of the wild type (C, arrowhead) but not in the ventral telencephalic region anterior to the optic recess of megalin^–/– embryos (D). (E,F) Frontal head aspects of wild type (E) and megalin^–/– E10.5 embryos (F), depicting Shh expression in the AEP (arrowheads) of wild-type but not knockout animals. Expression of Shh in other areas of the forebrain, such as in the basal plate of the diencephalon (bpd) or the zona limitans intrathalamica, is identical in both. (G-K) ISH for Shh on coronal sections of the rostral (G,H) and the caudal (I,K) neural tube. Shh is expressed in the AEP of the rostroventral neural tube of wild-type (G) but not megalin^–/– E10.5 embryos (H), while expression in caudal regions of the neural tube is identical in wild-type (I) and knockout tissues (K). bpd, basal plate of the diencephalon; fp, floorplate; or, optic recess; te, telencephalon; vp, ventral prosencephalon; Zli, Zona limitans intrathalamica.