[Ultrastructure of mast cells in nasal polyps]

More mast cells were found in the base of nasal polyps and most of them showed varying degrees of degranulation. There were three types of granules in the cytoplasm, namely: high electron-dense granules with crystalline structure; low electron-dense granules with netlike structure and some granules containing a mixture of components of different electron density. The appearance of cell degeneration in nasal polyps and granules broken away from mast cells through the dissolved cellular membrane were noted. These findings suggested that mast cells degranulation in nasal polyps might be in some way different from the more rapid changes found in cells activated by the classical IgE-mediated pathway and showed that mast cell degranulation may play a part in formation and growth of the nasal polyps.