Light microscope and fluorescence micrographs of LE (A–B) and ZD-LE (C–D) rats.

A) Bright-field image of the retina - RPE – choroid complex in LE rat. Black arrowheads show the regularity of the Bruch's membrane. B) Fluorescence micrograph of ED1 positive cells in the same area as in (A). ED1 immunoreactivity (white arrows) is visible in the choroid. C) Bright-field image of the RPE – choroid complex in ZD-LE rat. Black arrowheads show the irregularity of the Bruch's membrane, white arrowheads indicate RPE cells. D) Fluorescence micrograph of ED1 positive cells in the same area as in (C). Small (<3 µm) (white arrow) and large (>3 µm) (white asterisk) ED1 positive cells are detected in the choroid. ED1 immunoreactivity is also shown around choroidal blood vessels and along the choriocapillaris just below the Bruch's membrane (white arrowheads). A thin ED1 positive cell simultaneously in contact with the Bruch's membrane and a RPE cell (black arrow) is shown. In B and D), note the strong autofluorescence of the photoreceptor outer segments frequently observed in paraffin sections due to the fluorescence emitted by the retinoids reflecting the clearance of toxic byproducts and the accumulation of lipofuscin-like fluorophores associated with the increase of lipid peroxidation with age in the retina.