Effect of ZOL on the clonal cells derived from single spontaneous colonies in the culture of JMML BM cells. Five spontaneous colonies generated from BM cells of 3 patients with JMML at day 5 of clonal culture were individually lifted and divided equally, then each half was incubated in the suspension culture with or without 10 μM ZOL for 10 days. The proportion of monocytes/macrophages and granulocytes was determined on cytospin smears of the cultured cells cytochemically stained with α-NBE. ▪ indicates monocytes/macrophages; ▦, granulocytes.