Fig. 4. Identification of living cells that express the 185/333 proteins. Digitally enhanced phase-contrast microscopy of living cells (A,B) demonstrates the presence of small filopodial cells in populations of coelomocytes that appear similar to 185/333⁺ small phagocytes (Figs 1, 2, 3), but quite different from type 2 (polygonal; labeled 2 in A) or type 1 (discoidal; labeled 1 in B) coelomocytes. A type 1 coelomocyte with a characteristic radial cytoskeleton (labeled 1 in C) is shown adjacent to a smaller, filopodial small phagocyte in C. The 185/333 antibodies stain the entire small phagocyte and appear concentrated in punctate perinuclear structures (D). A type 2 coelomocyte (labeled 2 in E) with a characteristic distributed array of cytoplasmic granules is shown adjacent to a smaller, filopodial small phagocyte (E,F). Bars, 10 µm.