Since IPF lung sections labeled for claudin-10 display widespread of claudin-10-positive cells: i) accumulating in varied arrangement at hyperplastic bronchiolar epithelium and ii) floating as clusters in bronchiolar airspace [6], we had expected to find many cells with club cell morphology that are discernible under TEM observation. This evidence concerns the gene CLDN10 and idiopathic pulmonary fibrosis.