Immunoelectron microscopy of mitochondria in wild type, APP23, and APP48 mice. a: Immunoelectron microscopy revealed gold-labeled Aβ (arrows) within lipofuscin-like granules in the cytoplasm of frontocentral pyramidal neurons in 15-month-old APP23 mice. b. Most mitochondria in the somata of frontocentral pyramidal neurons in 15-month-old APP23 mice did not contain immunogold labeled Aβ-positive material (arrowheads). c: Only few neuronal mitochondria exhibited single gold particles in a 15-month-old APP23 mouse indicating anti-Aβ-positive material within these mitochondria (arrow). d: In a few mitochondria within frontocentral pyramidal nerve cell somata of 18-month-old APP48 mice we found immunogold labeled Aβ-positive material associated with the membranes of healthy-looking mitochondria (arrow). Neighboring non-altered mitochondria often did not contain Aβ (arrowheads). Aβ fibrils were not seen inside the mitochondria. e: Altered mitochondria within pyramidal neurons in the frontocentral cortex of a 18-month-old APP48 mouse also exhibited single gold particles in association with their membranes indicating the presence of Aβ (arrows) although Aβ fibrils were not observed inside the mitochondria. Due to the use of LR-white embedded tissue required for post-embedding immunoelectron microscopy (a,b) the tissue preservation was less good than in the Epon embedded sections used for the morphological analysis of the mitochondria (Figure
a-c). Calibration bar in e is valid for: a, b = 540 nm, c = 325 nm, d = 288 nm, e = 180 nm.