TheDrosophilamutantoralacks rhodopsin in the Rl-6 set of photoreceptors and has a diminution of the photopigment containing rhabdomeres of Rl-6. Newly emerged flies have rhabdomeres, albeit small, which extend from the distal rhabdomere cap to the proximal basement membrane. As the fly ages, these are reduced until only distal remnants remain. Carotenoid deprivation does not protectoraflies from rhabdomere loss. When first characterized,orawas designated as a non-formation mutant rather than a degeneration mutant. The truth lies between, since rhabdomeres diminish with age but cells do not die. The plasmalemma of Rl-6 have unusual dense striated areas like the“zippers”described earlier for theDrosophilamutantnorpA. Similar membranes are also present within the receptor somata, especially in young flies. The latter probably become internalized from the plasmalemma. They are likely not related to the diminished rhabdomeres as claimed earlier. R7 and R8 have normal rhabdomeres, and in particular, they have normal coated vesicles and multivesicular bodies (MVB's), early steps in the degradation phase of normal rhabdomere maintenance. No MVB's are seen in the Rl-6 somata, indicating that the routes for rhabdomere degradation differ from those of normal receptors. However, some MVB-like structures are seen in the intraommatidial cavity. The compound mutantrdgB;orahas a phenotype just like thatof ora. This means thatoraprotectsrdgBfrom the light induced degeneration of Rl-6 which characterizesrdgB.