Cilia have elsewhere been estimated to be 5 extended and 0:3 in diameter (Kuhn and Wright, 2005; Tomashefski et al., 2008). Inside the bronchi, the secretory cells are predominantly goblet cells, which have bulging apical surfaces covered by microvilli. Small mucous granule cells (SMGCs) are an further, rare secretory cell kind in the bronchi, and might essentially be morphological variants of