Heterozygotes with DrMio have reduced viability, deranged bristles, uncoordination and small eyes. Heterozygotes with DrME4 and other DrMio revertant alleles are embryonic lethal. Clonal patches in the eye are small and infrequent, in the ommatidia the outer photoreceptors carry distinctly small rhabdomeres and supernumerary photoreceptors are often present, R7 cell is wild type.
G. Jurgens.