For years biologists were so focused on the internal workings of cells that they pretty much ignored the “glue” that holds those cells together in a body, human or otherwise. And yet once researchers started looking deeper into the stuff between cells, known as the extracellular matrix, they began to realize just how dynamic the whole arrangement is. Not only does the overlooked matrix provide the biological scaffolding necessary to keep animal tissues and organs from dissolving into a gooey mess, but it also releases molecular signals that, among other things, help the body heal itself.