Liam Barry-Carroll

Keywords microglia border-associated macrophage microglia replacement brain immunology ontogeny monocyte neurodegeneration hematopoietic stem cell transplantation Introduction The brain has developed a symbiotic relationship with macrophages. Brain-derived signals instruct and support macrophages that, in turn, help maintain healthy brain homeostasis.

Abstract Microglia constitute the largest population of parenchymal macrophages in the brain and are considered a unique subset of central nervous system glial cells owing to their extra-embryonic origins in the yolk sac. During development, microglial progenitors readily proliferate and eventually colonize the entire brain.

Microglial proliferation is prominent in key neurodevelopmental structures ). Microglia are enriched in the PSP monolayer below the CP from the 10 The fetal SP is a major site for synaptogenesis and neuronal maturation, as well as a waiting compartment for cortical afferents (th pcw (Figures 3A and 4A). The SP is fully formed at 12.5 pcw by the gradual merging of the PSP and the deep, loose portion of the CP in parallel with the development of the afferent fiber system ( ).