A fine structure study of some cellular components in allergic reactions

Summary Skin samples from patients with Urticaria pigmentosa, Urticaria both spontaneous and induced, and from normal individuals has been examined and mast cell ullrastructure described. The features of mast cells in skin are compared with those in nasal and bronchiolar tissue and distinguishing features areas follows. (1) Skin mast cells tend to have longer villous extensions of plasma membrane. (2) Granules in skin mast cells have very frequent crystalline inclusions; these are uncommon in other tissues examined so far. Degranulation of the mast cells was observed and appears similar to that seen in other tissues.