The medulla contains both DC precursors and mature DC. Thymic tissue sections were triple-stained with anti-IL–3R (red), anti-CD83 (green), and anti-CD86 (blue). Patterns of the individual colors, which combined are shown in (A), are depicted separately in (B) (anti-CD83), (C) (anti-IL-3R ), and (D) (anti-CD86). As a comparison in (E), a control staining of anti-IL–3R (red), anti-CD83 (green), and control IgG (blue) is included. The round structure on the left side represents a Hassall’s corpuscle, which indicates the thymic medulla. Note in (A) the red stained pre-DC versus the blue/green stained mature DC. Original magnification ×400.