They form their own furls of cartilage around themselves. They're also, number three, the most efficient repairers of fractures that we've ever encountered. This is a little bone, a mouse bone that we fractured and then let it heal by itself. These stem cells have come in and repaired, in yellow, the bone, in white, the cartilage, almost completely. So much so that if you label them with a fluorescent dye you can see them like some kind of peculiar cellular glue coming into the area of a fracture, fixing it locally and then stopping their work.