Tissue sections from CY-treated Nf1+/− mice with MPD. (A and B) Blood and bone marrow smears showing immature and well differentiated myeloid cells. (C) A cytocentrifuge preparation of spleen cells stained with the myeloid lineage marker nonspecific esterase demonstrates many positive cells (brown stain). (D) A spleen section shows a dense infiltrate of myeloid cells within the red pulp.