Fig. 7
Dark vs typical microglia in aging human post-mortem brain samples. Representative 5 nm resolution scanning electron microscopy images in human post-mortem hippocampal head (post-mortem delay of 18 h) of (A) a 45-year old man and (B) a 81-year old woman. A Typical microglia (TM) positive for the myeloid cell marker Iba1 with healthy and altered mitochondria located next to a dark microglia (DM). The insets provide a zoom in view of the (B) TM and (C) DM. D TM with lipofuscin (labeled Lg) and mitochondria (orange asterisk) next to a DM displaying altered mitochondria (green asterisk), empty phagosomes (pseudocolored in cyan) and phagosomes with cellular contents (pseudocolored in pink). The insets provide a higher magnification of the (E) TM and (F) DM. Red outline = plasma membrane, yellow outline = nuclear membrane, ma = myelinated axons, A = axon terminals, orange asterisk = mitochondria, green asterisk = altered mitochondria, lb = lipid body, 3rd = tertiary lysosome, Lg = lipofuscin granules, pink pseudo-coloring = partially digested phagosome, cyan pseudo-coloring = fully digested phagosome