83% of cuticles from S218 homozygous embryos show fusion of at least one pair of denticle belts, with the majority having between 1 and 3 fusions.
30% of ommatidia show a reduction in the number of photoreceptor neurons in heterozygous animals.
Homozygous clones in the follicle cells result in weak ventralisation of the eggshell; dorsal appendages are partially or completely fused.
Heterozygous adults have very slightly rough eyes.
Clonal analysis of Star alleles shows that the progression of the morphogenetic furrow is delayed and dpp expression was inhibited near the clones.
Homozygous clones in the eye are always associated with a scar, surrounded by normal ommatidia of mixed genotype.
S218 has eye photoreceptor cell phenotype, enhanceable by edlJV/Df(2R)edl-L19
The loss of photoreceptor neurons seen in S218/+ animals is enhanced by edlJV/Df(2R)edl-L19; in the double mutant animals, 65% of ommatidia lack at least one photoreceptor neuron.
The S218/+ rough eye phenotype can be enhanced by mutations in Egfr or spi. S218 EgfrE3 double heterozygous adults exhibit severely reduced and rough eyes. Most ommatidia have a reduced number of photoreceptor cells, there are also defects in orientation, spacing and pigment cell and bristle numbers. This phenotype is more severe than a simple addition of the dominant effects of Egfr and S.
