Identification of dystrophic neurites. Electron microscopy was used to identify dystrophic neurites (arrows) as previously described
 and shown here in the frontocentral cortex of 15-month-old APP23 mice. Such neurites are characterized by neuritic swelling and contain vesicles with electron dense bodies (black arrowheads) probably representing autophagic vacuoles. Mitochondria in these neurites appear morphologically intact (M). Few multivesicular bodies are seen in these neurites as well (white arrowhead). The calibration bar corresponds to: 250 nm.