Despite intense study, the precise origin and cell lineage of microglia, the resident
mononuclear phagocytes of the nervous system, are still a matter for debate. Unlike
macroglia (astrocytes and oligodendrocytes) and neurons, which are derived from
neuroectoderm, microglial progenitors arise from peripheral mesodermal (myeloid) tissue.
The view still commonly held is that tissue-resident mononuclear phagocytes (including
microglia) are derived from circulating blood monocytes and these take up residence late in …