Immunohistochemical analysis of annexin I in normal tonsil. Panel A: CD 20 staining of normal tonsil reveals clusters of B-cells referred to as germinal centers. Panel B: Annexin I staining of the next serial section shows annexin I presence in tonsil epithelium with weak immunopositivity in the germinal centers. At higher magnifications (panels C and D), distinct cytoplasmic staining of annexin I is observed in a subset of cells (panel D) that represent the germinal center CD 20 positive cells (panel C). Magnification: 40× (panels A and B), 400× (panels C and D).