Analysis of the ploidy of p21^−/− and p21^+/+ CF1 megakaryocytes.

Bone marrow cells were stained with a FITC anti-CD41 mAb and then incubated overnight in a hypotonic solution of PI. Samples were analyzed by flow cytometry. (A) Representative histograms. (i) (iii): Fresh bone marrow. (ii) (iv): Lin⁻ cells stimulated by PEG-rHuMGDF and SCF were cultured for 3 days and ploidy was measured. Histograms are from a representative experiment (n = 7 for fresh marrow cells, n = 3 for cultured cells). (B) Analysis of the mean ploidy. Bone marrow megakaryocyte ploidy of 7 animals in each group was studied. No significant difference was observed between ploidy of p21^−/− and CF1 mice.