Composite transmission electron microscopic image of the retinal pigment epithelium of an 80-year-old human donor.

A 150 nm thick non-osmicated section was collected on a formvar-covered copper mesh grid, placed in a drop of water on a glass slide, coverslipped and investigated with light and fluorescence microscopy. Subsequently, the grid was recovered, air dried and imaged without any further heavy metal staining with a transmission electron microscope. The image is composed of 20 individual images taken at x12,000 magnification. Asterisks mark artifacts due to dirt. Melanosomes appear black due to their intrinsic electron density. Lipofuscin granules are medium gray. Melanolipofucin granules can be identified by a melanosome core with a lipofuscin shell or one or several lipofuscin protrusions.