Identification of p63-specific cells in clusters. (A) Light micrograph of a representative cluster on day 4. (B) DAPI-stained cell cluster. (C) Immunostained p63-positive cells in the cluster. (D) Magnified micrograph of p63+ cells. (A through C) The same cluster is imaged with different filter settings (scale bar, 100 μm). (D) Scale bar, 50 μm; D1 40×.