Expression of fzhs.sev results in more than 70% of ommatidia being symmetrical.
Expression of one copy of fzhs.sev causes strong planar cell polarity defects in the eye.
Flies expressing fzhs.sev show randomisation of chirality and rotation of the ommatidia. Many ommatidia are symmetrical, with both R4 and R3 cells developing as an R3 cell.
The ommatidia appear disorganised in flies expressing fzhs.sev, polarity is random and many ommatidial clusters remain symmetrical (showing R3/R3-type symmetry). In ommatidia that are mosaic in the R3/R4 photoreceptors, the fzhs.sev cell always adopts the R3 fate. This can lead to polarity reversals and inverted chirality.
Expression of fzhs.sev in a fz- background (fz15 or fz37) in either the presumptive R3 or R4 cell in mosaic ommatidia causes the cell expressing fzhs.sev to become an R3 cell and the other to become an R4 cell. Ommatidia with inappropriate chirality arise at the mosaic interface in eyes that are mosaic for fzhs.sev (in a wild-type background). In all these incorrectly patterned ommatidia, either one or both members of the R3/R4 pair carries fzhs.sev. In these cases, whenever the R3/R4 pair are mosaic, the R3 cell always carries fzhs.sev. The R3 cell also invariably carries fzhs.sev in chirally correct ommatidia that are mosaic for the R3/R4 pair.
Ommatidial orientations are disturbed, chiral shape is choosen randomly. Heat induced expression in embryos causes nearly all the cells secrete smooth cuticle and narrow denticle belts are observed (deletion of the first 3-4 anterior rows of denticles). Weakly affected denticle belts only affect the first row of denticles.