Fig. 1. (A-C) her6 is weakly expressed by cells in the blastoderm margin (arrows) throughout epiboly. (A) Dorsal view of a 70% epiboly embryo. (B,C) Lateral (B) and vegetal (C) pole view of a 90% epiboly embryo. In A and B, anterior is towards the top; in B, dorsal is rightwards. In A and B, the arrowhead indicates her6 expression in the anterior epiblast. (D-F) After the end of epiboly, her6 is expressed in the tailbud until about the five-somite stage (arrows in D,E), in the posterior compartment of all somites and in two stripes in the anterior PSM. (D) Vegetal pole view of a two-somite stage embryo, dorsal is rightwards. (E,F) Dorsal views of a four-somite stage (E) and a 10-somite stage (F) embryos. Arrowheads indicate her6 expression in the margins of the neural plate (E) and in the posterior lateral mesoderm (F). (G,H) her6 expression identifies the posterior compartment of the forming somite (S0) and of the first prospective somite (S-1). her6 expression (dark blue staining in G and H) overlaps with the expression of the prospective posterior compartment marker, myod (red staining in G), and intercalates with the expression of the prospective anterior compartment marker, papc (red staining in H).