Fig. 4. Expression of MHB genes is reduced in spgm793 mutants. Expression of wnt1 (A-H), pax2.1 (I-P) and eng2 (Q-X) in wild-type and spgm793 mutant embryos. Embryonic genotypes are indicated at left, developmental stages, above. 90-100% epiboly and the two-somite stage embryos are shown in dorsal views, anterior/animal pole is at top. 90-100% epiboly stage embryos were genotyped by allele-specific PCR (see Materials and Methods). Five-somite stage and 1 dpf embryos are depicted in lateral views of the head region, anterior towards the left and dorsal upwards; images are focused at a mid-sagittal plane. 90%-100%, 90%-100% epiboly; som, somite (stage); hb, hindbrain; os, optic stalk; op, otic placode; rp, roof plate.