Immuno-and enzyme-histokytochemical analysis of resin sections and cell suspensions: a comprehensive diagnosis of bone marrow on a single aspiration sample by M. M. VAN DE SANDT, C. J. HER MAN^^^ J. L~~~~~~~~S t i c h t i n g S a~w e r k i n g Delftse Ziekenhuizen, Reynier de Graejbeg 7,2625 AD Delft, The Netherlands KEY WORDS.Bone marrow, resin embedding, immuno-histochemistry, enzymehistochemistry, haematology . SUMMARY A protocol is described in which a single bone marrow aspiration specimen is used to prepare resin sections and cell suspensions. Using this protocol, a full battery of morphological, enzyme-histochemical, immuno-histochemical and cyto-pathological techniques can be applied. This allows a definitive bone marrow diagnosis to be established without resorting to bone marrow biopsy in the majority of patients.