ommatidium pale ommatidium The pale ommatidium expresses the near ultraviolet-specific opsin Rh3 (FBgn0003249) in photoreceptor R7 cells and the blue-sensitive Rh5 (FBgn0014019) in photoreceptor R8 cells (Wernet and Desplan, 2004). FBbt:02000002 fly_anatomy.ontology Ommatidial subtype with stochastic distribution throughout the retina, making up about 30% of all non-dorsal margin ommatidia. This ommatidial subtype is specialized to detect shorter wavelengths (near UV + blue) than yellow ommatidia. VFB:FBbt_02000002