Fig. 1. Molecular characterization of medullary thymic conduits. The micrographs show single (A-D) or double (E-N) immunofluorescence staining with Cy3- or FITC-labeled antibodies counterstained in blue with DAPI to visualize cell nuclei. (A,B) Labeling with antibody specific for the
2 chain of the LN-5 isoform showed an exclusive staining of structures located in the medulla (A). Upon enlargement, bi-membranous structures or conduits, with an average diameter of 2 µm, can be clearly detected (B). (C,D) The laminin
3 chain (LN
3; C) and the laminin ß3 chain (LN5ß3; D), both components of the LN-5 isoform, are also detected in the conduits. (E-H) Typical basement membrane components are found in LN-5-containing conduits, as shown by double immunofluorescence staining with antibody specific for the ß3 chain (LN5ß3; G) or the
2 chain (LN5
2; E,F,H) of the LN-5 isoform plus collagen type IV (E), perlecan (F), nidogen (G) and EHS-laminin (EHS-LN; H) antisera. (I-K) Fibrillins and tenascin-C are also associated with the conduits. This is shown by double labeling with fibrillin-1 and laminin
2 chain antibodies (I), with fibrillin-2 and laminin ß3 chain antibodies (J) and tenascin-C and collagen type XII antibodies (K). Other collagen types associated with the conduits are the fibrillar collagen type I (L) and type III (N) or the microfibrillar collagen type VI (M). Here, the conduits were labeled with laminin
2 chain (L), laminin ß3 chain (M) or EHS-laminin (N) antibodies. Bar, 10 µm.