Figure 1.

Human RPE in cross-section and in manually reconstructed 3D view. In the eye of a 21-year-old organ donor preserved minutes after withdrawal of life support, attachment of the neurosensory retina to the RPE was preserved, and the relevant ultrastructure was differentiated in the perifoveal area. Although the photoreceptors are attached to the RPE, the outer segments are bent and appear as cross-sections. Granules in the cell body are highly electron dense. Individual subtypes are not distinguishable. Colors: red, borders of cell body; turquoise, cell nucleus; yellow, melanosomes in apical processes; brown, lipofuscin granules in apical processes; green, rod photoreceptor outer segments; blue, cone photoreceptor outer segments; pink, apical processes. (A) Cone outer segment with surrounding RPE apical processes containing a melanosome. (B) Rod outer segment with RPE apical processes containing two melanosomes. (C) Single cross-sectional transmission electron micrograph showing RPE attached to outer segments; Bruch's membrane is not present. (D) Volumetric manual reconstruction of a binucleate (turquoise) RPE cell body including cone (blue) and rod (green) photoreceptor outer segments and melanosome granules (yellow) located in apical processes (pink).