Fig. 5. Constitutive Notch activity promotes her4 and inhibits ntl expression. (A) Transverse section showing lateral region of 9.5 hpf embryo in which NICDMT expression was induced during gastrulation. Some cells that expressed NICDMT (brown) also expressed her4 (blue, arrows). (B,C) Dorsal views, anterior towards the top, of 9.5 hpf embryos labeled for ntl (blue) and NICDMT (brown) expression. These embryos were injected with mRNA encoding NICDMT in a single cell at the eight-cell stage. (B) Embryos in which NICDMT-positive cells were restricted to ventrolateral regions (asterisks). Midline cells expressed ntl normally (arrows). (C) Embryos in which NICDMT-expressing cells occupied the dorsal midline region. These embryos had fewer midline cells that expressed ntl (arrows). (D) Transverse section through dorsal midline region of 9.5 hpf embryo treated as embryos described in B,C. Two NICDMT-positive cells (brown, arrows) occupied the notochord precursor domain but did not express ntl (blue), whereas neighboring cells expressed ntl normally. Scale bar: 20 µm in A,D; 120 µm in B,C.