EM was also pivotal in shedding light on certain astrocytic dysfunctions in AD, including mitochondrial ultrastructural alterations (Baloyannis, 2019) and the autophagic functions in vitro of APOE3 and APOE4 astrocytic cells from the cerebral cortices of postnatal day 1–3 mice (Simonovitch et al., 2016). The gene discussed is APOE; the disease is Alzheimer disease.