PAS-positively stained neutrophilic granulocytes in bone marrow smear (human)

Stain: Periodic acid-Schiff reaction (PAS). Mature neutrophils (1) have fine positive granules within negatively (un)stained cytoplasm, whereas eosinophils (2) and basophils show a positive cytoplasmic reaction contrasting with the negative granules. In lymphocytes (1) PAS-positive granules are rare but their number increases in reactive processes, e.g. infectious mononucleosis and viral infections, and in lymphoproliferative disorders such as chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma.