Unfused myoblasts are apparent in HemG1-37 mutant embryos until stage 15. By stage 16 hardly any unfused myoblasts are present, but there are large gaps in the muscle pattern and epidermal-muscle attachments are frequently missing or incorrect. Dorsal closure is normal in these embryos, as is formation of the dorsal vessel and cardioblasts.
The reduction of myoblast fusion seen in stage 15 HemG1-37/HemG1-37 embryos is enhanced by blow2/+. The muscle fusion phenotype of double homozygous blow2; HemG1-37 embryos resembles that of blow2 homozygotes rather than HemG1-37 homozygotes.