Regionalized expression of upregulated genes in the hypothalamus in DAPT-treated chick embryos. Whole embryo in situ hybridization was performed with Ascl1 (A-C), Nhlh1 (D-F), Stmn2 (G-I), Slit1 (J-L), Robo2 (M-O), Tagln3 (P-R), Chga (S-U) and Chrdl1 (V-X) riboprobes on control and DAPT-treated embryos after 16 hours ex-ovo culture and on Hamburger and Hamilton (HH)15 embryos as indicated on the figure. In B, E, H, K, N, Q, T and W, mesenchymal cells and surface ectoderm were removed to obtain dissected neural tubes (ventral view) from the embryo described on the left side. Small arrows highlight specific expression of all these probes in the rostral hypothalamus. Arrowheads point to the expression in the olfactory epithelium. g, ganglia; m, roof of the mesencephalon; o, optic vesicles. DAPT, N-[3.5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester.