Insertion in the first exon.
Muscle M12 appears to differentiate into a muscle fiber of normal size in mutant embryos. However, its position is shifted towards the ventral nerve cord compared to wild type and it is situated ventral to muscle M13 and underneath (external to) muscle 6/7 in the mutant embryos. The normally longitudinal orientation of the muscle becomes oblique because the ventral shift of the muscle attachment is more severe for the posterior than the anterior attachment site.
Homozygous and tey5053A/Df(3L)Exel6135 embryos have a single large synaptic terminal region between muscles M12 and M13, in contrast to wild-type embryos which have two discrete endings which are on the proximal edges of muscles M12 and M13 respectively.
