Evaluation of TPO-induced proliferation and differentiation along the megakaryocytic lineage of CD34⁺ cells. In (A), viable cells were scored by Trypan blue dye exclusion after various days of liquid cultures supplemented with 100 ng/mL of TPO. Data are expressed as the means ± SD of three separate experiments performed in duplicate. In (B), cytospins were observed at light microscopy after May-Grünwald-Giemsa staining. Original magnification (OM) × 400.