Tryptase immunohistochemical staining for mast cell (MC) infiltration and degranulation in rat nasal mucosa invaded by
. Both tryptase-positive MCs and tryptase-positive granules are stained dark brown. (Original magnification × 40 in A, ×20 in C, and × 100 in B and D). Red arrow indicates MC infiltration and degranulation. Black arrow indicates A. fumigatus hyphae.