As you read this, an army of cells is patrolling your brain. These soldiers slither around neurons, using their long limbs to search for threats. When one of them senses a pathogen or injury, it springs into action, swelling with ravenous attack and releasing chemicals that signal its allies to join the fight as it descends.
These specialized immune cells, known as microglia, are our brain’s primary guardians: They protect us from invaders, remove debris, and maintain connections between neurons to keep your brain in tip-top condition.
But despite their vigilance, microglia sometimes turn on their own troops, and there is growing evidence that they may be responsible for some of the brain’s most intractable ailments, including Alzheimer’s and depression. If so, targeting the wayward defenders, or replacing them with younger troops, could offer exciting new treatments.
Microglia were discovered in 1919 by neuroscientist Pio del Rio Hortega, who came across the new cells by chance while experimenting with new ways to stain brain tissue and named them after the ancient Greek words meaning “small” and “glue.”
This turns out to be an inadequate explanation: Aside from their patchy appearance, microglia have little if any adhesive properties. Instead, they are among the most dynamic cells in the body, darting about in the brain with long, tentacle-like processes that expand and contract in response to changing environments.
Microglial Functions
Microglia are a type of macrophage, a type of immune cell, and their role is…
