Triple synaptophysin (brown chromogen), p40 (green chromogen), and POU2F3 (red chromogen) IHC in representative bronchiolar cross-sections shows nuclear POU2F3 expression in rare cells that are distinct from the flask-shaped synaptophysin-positive resident pulmonary neuroendocrine cells, with POU2F3-positive nuclei overlying a discretely separate continuous p40-positive basal cell layer and located at or above the level of ciliated cell nuclei.
Abbreviations: IHC immunohistochemistry, SYN synaptophysin