All flies carrying ptc^tuf-1 in trans to ptc³⁷ have severely reduced, rough eyes, a highly enlarged head vertex (ocellar triangle, fronto-orbital plate and frons), outgrowths of head cuticle and large numbers of missing, misplaced or ectopic head bristles. ptc^559.1/ptc³⁷ flies have mildly reduced eyes, a slightly enlarged head vertex (ocellar triangle, fronto-orbital plate and frons) and low incidences of head cuticle outgrowths and ectopic or misplaced head bristles. The zone of cell cycle arrest corresponding to the morphogenetic furrow (MF) is not significantly increased in late 3rd instar ptc³⁷/ptc^tuf-1 or eye discs compared to wild-type. However, its width is uneven along the length of the furrow, being particularly narrow at the equator and wider along the margins. The distribution of dividing cells either side of the MF is disorganized: dividing cells anterior and posterior to the furrow are closer together near the equator of the disc than at the poles. Compared with wild type, there is an approximately 2 fold increase in cell division ahead of the furrow in the mutants.

homozygous and hemizygous mutants display distortion in the costal cell and an increase in the distance between the L3 and L4 wing veins.