Figure EV4. Histological characterization of human lung tissue of IPF patients.

• A, B
  Microphotographs of H&E (upper panel in each case) and Masson's trichrome (bottom panel in each case) staining in paraffin‐embedded lung tissue sections from two histologically normal lungs (controls) (A) and seven IPF patients (B). As it can be observed in (A) control lung tissue is characterized by a thin pulmonary alveolar epithelium. Neither fibroblast nor ECM deposits are present in the interstitium. In IPF patients (B), an extensive pulmonary fibrosis was observed in all the specimens analyzed. Alveolar interstitium is fully occupied by fibroblasts, inflammatory infiltrates and markedly visible ECM deposits (blue in Masson's staining for collagen). Alveolar epithelium is barely observed due to fibrosis development. All images are shown at equal magnification. Scale bar: 100 μm.