Homozygous embryos exhibit five ventral oblique muscles instead of three (as in wild type embryos). Embryonic muscle loss is due to defects in early somatic differentiation. Severe abnormalities are observed in a subset of pericardial cells.
Supernumerary muscles develop at the expense of the adult muscle precursors in homozygous embryos. The segment border muscle is duplicated at the expense of the lateral adult muscle precursors. Muscle LT3 is transformed to LT4.
Fusion defects of myoblasts.
Muscle pattern is reduced (ventral and pleural muscles) and disorganised (ventral lateral and dorsal muscles). The dorsal vessel is fairly normal. Most dorsal muscles are formed and inserted appropriately in the apodemes. Pattern formation of the cuticle is normal suggesting the observed muscle phenotype is not a consequence of epidermis defects.