In embryos expressing twi^2x.Scer\UAS under the control of Scer\GAL4^twi.PG the cells at the distal tips of the salivary glands are spread out over the corner of the undifferentiated midgut. The salivary glands are often overelongated and have their distal tips in contact with the area of the midgut that forms the gastric caecae in wild type. Additionally, the anterior migration and differentiation of the longitudinal muscle layer cells are defective.

Over expression of twi^2x.Scer\UAS when driven by Scer\GAL4^twi.PB converts non-somatic mesoderm into somatic muscle. Ectopic multinucleated somatic muscle cells are detected dorsally where the heart normally forms and around the gut and central nervous system. These muscles do not spread out and form a pattern owing to lack of epidermis. A concomitant loss in cells contributing to other mesodermal tissues is seen. Progenitors of the visceral muscles and fat body are reduced. A decrease in both pericardial and cardial cells are seen. The migration of the mesoderm is normal. The addition of twi^2x.Scer\UAS to homozygous twi¹ leads to animals in which somatic muscles form but with an aberrant pattern.