Morphology of single-cell–derived colonies. A typical mast cell colony grown in the presence of SF + IL-6 (A). A typical macrophage colony (B) and a typical basophil colony (C) grown in the presence of IL-3. The colony (A)-derived mast cells stained with May-Giemsa (D) or antitryptase immunostaining (E). May-Giemsa staining of a basophil (top) and an eosinophil (bottom) found in a mixed basophil-eosinophil colony (F). Original magnification: ×183 (A, B, and C), ×1100 (D and F), and ×733 (E).