Fig. 5. Organization of retinulae from the yellow retina and dorsal rim. (A) Tracings of electron micrographs from sectioned retinulae near the center of the retina, showing the component photoreceptors and their rhabdomeres (shaded). The dorsal-ventral axis of the retina is vertical. The depth of each retinular profile from the surface of the retina (see Fig. 3) is indicated. dv, dorsal-ventral receptor cells; ap, anterior-posterior cells; ob, oblique cells; pr, proximal cell. (B) Tracing from electron micrograph of a retinula from the dorsal rim area. The structures of the eight elongate receptor cells do not vary with retinal depth (the basal pr cell has not yet been found). Only the ventral dv cell is present. Orientations of photoreceptor microvilli are indicated by double-headed arrows. Scale bar, 1 µm.