|
Fig. 1 Distribution of her4 transcripts revealed by whole-mount in situ hybridization. (A) 70% epiboly. her4 expression appears in the epibolic margin, the midline is devoid of transcript. (B) 90% epiboly. A row of hypoblastic her4-expressing cells is visible on either side of the midline (arrows). (C) 100% epiboly. her4 expression in two lateral stripes in the neural plate (is) and in a V-shaped expression domain (asterisk) in the prospective brain region; the hypoblastic expression domains elongate anteriorly. (D) Flat preparation of a tailbud-stage embryo. Expression domains in the neural plate comprise two lateral stripes, one in an intermediate position (is) and one further lateral and caudal (ls), which will fuse during later stages of development; in addition there is a medial stripe in the neural plate which overlies the hypoblastic expression domain. (E) 1- somite stage. The intermediate and lateral expression domains are still distinct. (F) 2- somite stage. Intermediate and lateral expression domains have fused and the medial stripe has elongated. her4 transcription in the primordium of the trigeminal ganglion (trg) becomes visible. (G) 5-somite stage. (H) 24 h embryo. her4 transcription is detectable in two bands in the presomitic mesoderm. (I) Transverse section through the 90% epiboly embryo shown in B, which reveals the hypoblastic expression (arrows). (J) Transverse section through a 6-somite embryo, showing the lateral and medial expression domains in the neural plate, and the hypoblastic expression in the adaxial mesoderm.