Fig. 4. Spaw expression in midline mutants. (A-E) Dorsal views, anterior is towards the top. Dig-spaw probe. (F) Coordinate axes: A, anterior; P, posterior; L, left; R, right. (A,B) Ten to 12 somite stage, ntl^b160/ntl^b160 (abbreviated ntl^–/– in figure) Asterisk indicates tailbud; arrowheads indicate left and right lateral plate. (C) Seventeen to 19 somites. Wild-type sibling (sib) from a ntl^b160/+ incross. Arrow indicates ectopic spaw. (D) Sixteen to 20 somite embryo, sqt^cz35/sqt^cz35 (abbreviated sqt^–/– in figure) Arrowheads indicate bilateral spaw expression in lateral plate. Inset shows lateral view of tailbud. (E) Seventeen to 18 somites, boz^m168/boz^m168. Arrowhead indicates right-sided spaw domain. (G,H) Shield stage, looking down on blastoderm, dorsal towards the right, Dig-goosecoid probe. (G) Uninjected control. (H) Injected with 25 pg pCS2+ActHASpaw plasmid.