Figure 1. Representative electron micrograph of pigmented rat retina at postnatal day 6

At PN6, the photoreceptor inner segments with their numerous well-preserved mitochondria are well developed. In contrast, the photoreceptor outer segments are just beginning to form at PN6 (arrows). A cilium extending towards the retinal pigment epithelium (rpe) is evident. (x11,500; bar = 1 µm)