Expression of ttk69.ΔN153.Scer\UAS under the control of Scer\GAL4hs.2sev results in almost normal photoreceptor cell and cone cell development, but some subtle defects are seen such as missing retinal bristle group cells in pupal eye discs. Adult eyes are normal in size but many retinal bristles are missing. R4 to R3 cell transformation is seen in 10% of the ommatidia and occasionally R4 is transformed into an R7-like cell (1%) and R7 is absent (0.5%).