Ploidy distribution of normal human megakaryocytes.

The distribution of the marrow cells according to the membrane-CD41a (GPIIb/IIIa) immunofluorescence (FL1) and the DNA content (FL3) is shown (A). Cells with background fluorescence (below the horizontal line) represent the major marrow cell population with ploidy classes of 2N and 4N. The highly fluorescent cells (above the horizontal line) represent the megakaryocyte population with polyploid subclasses, as demonstrated in the DNA histogram (B). The modal ploidy is 16N cells comprising about 50% of the total MKs. Three thousand MKs, consisting of 0.05% of the total nucleated marrow cells, were analyzed. To improve visualization, the presentation of the MK population was electronically enhanced in panel A.