Abstract: Microglial cells are the only resident immune cells in the central nervous system and constitute its frontline guardian. They are extremely reactive against infections, trauma, or toxins, but are also responsible for mediating inflammation, taking part in the pathogenic course of many neuropathologies (Sierra et al., 2019). Cell-specific staining, ultrastructural analysis by transmission electron microscopy (TEM), or two-photon-microscopy imaging have been relevant for the characterization of microglia as well as their cell-cell interactions, which have led to a better understanding of microglial roles in health and disease.