When we speak of brain cells we usually mean neurons: those gregarious, energetic darlings of cell biology that intertwine their many branches in complex webs and constantly crackle with their own electric chatter. But neurons make up only half the cells in the brain. The rest, known as neuroglia or simply glia, have long lived in the neuron’s shadow.
French physiologist Henri Dutrochet first documented glia in 1824, though he had no idea what they were—he simply noted globules between the nerves of mollusks. In 1856, German biologist Rudolf Virchow gave those blobs the name “neuroglia,” describing them as “a sort of putty in which the nervous elements are embedded.” In the following decades, scientists learned that this putty was in fact made of individual cells—at least six major types, we now know—that formed intricate structural networks with both neurons and blood vessels. Yet they still regarded glia (which is Greek for “glue”) as mere fluff ‘n stuff, the brain’s packing peanuts, an inert plasma holding everything else in place.