Fig. 6

Glycogen granules in the cytoplasm of dark vs typical microglia. Representative 5 nm resolution scanning electron microscopy images captured in the ventral hippocampus CA1 stratum lacunosum-moleculare of 20-month-old APP-PS1 male mice. A Typical microglia (TM) near extracellular fibrillar Aβ (NTM) and (C) dark microglia (DM) near Aβ (NDM), both presenting glycogen granules in their cytoplasm (white arrow). B–D represent the insets of A and C, respectively. E Graph representing the proportion of microglia positive for glycogen granules. Data shown are expressed as means ± S.E.M. *p < 0.05, ****p < 0.001 using a Kruskal–Wallis test with a post hoc Dunn’s multiple comparisons test. Statistical tests were performed on n = 9–12 microglia per animal with N = 3 mice/group, for a total of 111 microglial cell bodies analyzed. Red outline = plasma membrane, yellow outline = nuclear membrane, while arrow = glycogen granules