At Johns Hopkins Medicine, scientists have done something quietly remarkable: they have watched the body build one of its smallest organs, frame by frame, in four dimensions. By capturing hundreds of hair follicles mid-development and arranging them by molecular age, researchers transformed still images into a living record of how skin becomes a hair-producing machine — and, crucially, what goes wrong when it cannot. The work opens a door toward understanding hair loss not as a single condition but as a spectrum of breakdowns in a precise biological choreography, each potentially addressable o