Immunohistochemical stainings for E- and N-cadherin and β-catenin during alveolar period of developing human lung. 4A and 4B. Type II pneumocytes (short arrows) and bronchial epithelial cells (arrows) display a positive staining for E-cadherin. 4C. Alveoli do not show any positivity for N-cadherin. 4 D. Type II pneumocytes of alveoli (arrows) are strongly positive for β-catenin. 4F. An example of vimentin staining showing that alveoli are positive for it. 4G. A negative control in which the primary antibody has been substituted with non-immune serum. 4 H. A negative control in which the primary antibody has been substituted with PBS with haematoxylin counterstain. Scale bars = 40 μm in 4A, 4C and 4D; scale bars = 20 μm in 4B, 4E, 4F, 4G and 4 H.