Figure 3

Claudin (CLDN)3 positivity in benign breast tissue and invasive ductal breast carcinoma. (a) CLDN3 positivity in benign breast tissue. Regular immunohistochemical reaction of benign breast epithelial cells using polyclonal CLDN3 antibody. Continous membrane staining characterizes most of the luminal epithelial cells. Sections were counter-stained with Mayer's haemalaun. The chromogen substrate was aminoethylcarbazol. (Original magnification: 400×.) (b) CLDN3 positivity in invasive ductal breast carcinoma. CLDN3 positivity is apparent in the membranes of some carcinoma cells. Sections were counter-stained with Mayer's hemalaun. The chromogen substrate was aminoethylcarbazol. (Original magnification: 600×.) (c) CLDN3 positivity in benign breast epithelium. CLDN3 positivity is seen in the majority of the membranes of benign epithelial cells. CLDN3 appeared to be localized in normal breast close to the apical end of the cell membranes or in the basolateral membranes of the epithelial cells. The primary antibody was CLDN3 polyclonal antibody (Zymed); the secondary antibody was IgG conjugated to Alexafluor 488 (Molecular Probes). Cell nuclei were counter-stained with propidium iodide. The image was obtained using laser scanning confocal microscopy (MRC 1024; Bio-Rad). (Original magnification: 400×.) (d) CLDN3 positivity in benign breast epithelium. CLDN3 positivity is seen in the membranes of the majority of breast epithelial cells. The positive membrane reaction is incomplete in most of the cells. The primary antibody was CLDN3 polyclonal antibody (Zymed). Sections were counter-stained with Mayer's haemalaun. The chromogen substrate was aminoethylcarbazol. (Original magnification: 400×.)