EV3C3V. Immunohistochemical staining of E13.5 - E21.5 normal lungs and E15.5 - E21.5 hypoplastic lungs with EV3C3V. In normal lungs, the EV3C3V epitope is displayed by the epithelium at E13.5 - E17.5 and in the underlying basement membranes at E13.5 - E21.5. A gradient of epitope expression is observed in the mesenchyme, with highest levels in sub-epithelial mesenchyme around smaller, distal airways and lower levels in sub-mesothelial mesenchyme. However, in hypoplastic lungs, this gradient of mesenchymal expression is lost, and the EV3C3V epitope is more extensively and evenly distributed throughout the entire mesenchyme. In addition, epithelial staining is lost from hypoplastic lungs and basement membrane staining is irregular. As a negative control, endogenous HS was digested with heparitinase prior to antibody incubation. (aw) airway, (mes) mesenchyme, (ep) epithelium, (bm) basement membrane, (br) bronchus.