Figure 4
Expression analysis of fragilis2 by in situ hybridisation on sections. (a-d) transverse sections through the caudal region of an embryo at E9.5 (approx. 25 somites) at progressively rostral levels. At most caudal levels, fragilis2 expression is seen in cells of the neural tube, in the presomitic mesoderm, in single cells within the hindgut (arrowhead) and in the body wall. (b) staining at approx. 23rd somite level is present within the forming somite, the body wall mesoderm and cells within the hindgut as well as the floorplate. (c) at approx. 21st somite level, expression in the differentiating somites is reduced, while cells in the floor plate and within the hindgut remain fragilis2 mRNA positive. (d) at approx. the 13th somite level, fragilis2 expression is absent from the somatic mesoderm as well as the neural tube. (e) sagittal section through an E10.5 embryo shows fragilis2 expression in developing lung tissue (asterix; higher magnification in f) and migrating cells along the hindgut anterior to the dorsal aorta (arrow). (g) shows a magnified view of fragilis2 mRNA expressing, migrating cells. da: dorsal aorta; fp: floor plate; g: gut; h: developing heart; nt: neural tube; s: somite; bw: body wall; scale bars: 150 μm (a-d); 1 mm (e); 400 μ m (f, g).