Fig. 5. Associations of conduits with non-lymphoid cells of the thymic medulla. (A-C) The micrographs show double immunofluorescence staining of a thymic cryostat section with antibodies against (C) cytokeratin, which detects TECs, and antibodies against (B) laminin 2 chain, which reveals thymic conduits. The merged picture (A), which is counterstained with DAPI to visualize the cell nuclei, revealed that the TECs are closely associated with the conduits. (D-F) Double immunofluorescence staining with antibodies against (F) CD11c, which detects dendritic cells, and antibodies against (E) laminin ß3 chain, which reveals thymic conduits, especially in the merged picture that is counterstained with DAPI (D), reveals that CD11c⁺ dendritic cells can be detected in close vicinity to the thymic conduits. (G-I) TECs express MHC class II molecules on their cell surfaces as indicated by the double immunofluorescence staining with antibodies against cytokeratin (I) and antibodies against HLA-DR class II molecules (H). The overlay picture clearly shows the colocalization (G). Bar, 10 µm.