Hystological analysis of tumours. A: Selected examples of H&E stained sections of the entire subcutaneous xenografted tumour induced by Calu-3 injection in untreated (C) and erlotinib (Erl), cetuximab (Cet) or erlotinib + cetuximab (Erl + Cet) treated BALB/c nude mice (scale bars: 1 mm). Higher magnification of the same samples are shown on corresponding panels in B (scale bars: 500 μm). C: representative morphological details of the control neoplastic epithelium (1, H&E) expressing cytokeratin (2,* brown-immunoperoxidase) that also depicts the epidermis (arrowhead). The presence of inflammatory interstitial cells in a cetuximab treated tumour (3, H&E) and the intense collagen deposition (bluish) surrounding neoplastic glands (purple) in a Erl + Cet treated tumour (4, Masson’s trichrome) are shown (scale bars: 100 μm). D: Bar graphs illustrating the quantitative measurements of neoplastic, inflammatory cells and stromal compartments composing the tumours. (*p < 0.05, **p < 0.01, vs control; #p < 0.05, ##p < 0.01 vs erlotinib; §p < 0.05 vs cetuximab).