Immunochemical staining for human mast cell-specific chymase in mesentery, lymph nodes, and spleen. (A) In the mesentery, human mast cells formed clusters consisting of 2 to 6 chymase⁺ cells. (B) In the lymph nodes, chymase⁺ cells localized around vessels in the trabecula. (C-D) Abundant chymase⁺ cells were extensively distributed in the red pulp but not in the white pulp of the spleen. Magnification, × 400 (A-B,D) and × 100 (C).