Effectiveness of EBEC isolation procedure and purity of fresh isolates. [a-b] Representative H&E staining of equine bronchial tissue before (a) and after (b) 2 h exposure to 0.25% trypsin-EDTA (objective magnification: ×10). Arrows indicate the intact epithelium before digestion and the complete removal of epithelium from the underlying connective tissue after trypsin digestion. [c-d] Representative immunocytochemical staining of cytocentrifuged fresh EBEC for the epithelial cell markers cytokeratins 5/6/18 (c) and the mesenchymal cell marker vimentin (d) (objective magnification: ×40). Green fluorescence (FITC) stain indicates positive signal. Nuclei are blue stained with DAPI.