Morphologic analyses of iMKs and iMK-derived platelets and characterization of iMK-derived platelets. (A) Electron micrographs. (Left) An iMK derived from HDF cells transfected with p45NF-E2, Maf G, and Maf K. N indicates nucleus; G, granule; DMS, demarcation membrane system; and M, mitochondria. (Middle) A large adult HDF cell before the induction of MKs as in left panel. (Right) An iMK-derived platelet. M indicates mitochondria; and OCS, open canalicular system. Original magnification, ×2500. A 5-μm bar is included in each right lower corner. (B) Expression of VWF in iMK-derived platelets onto fibrinogen-coated glass in the presence of 10μM ADP, 10μM epinephrine, and 10μM PAR1-activating peptide. Pictures were taken with a 63× oil objective. A 5 μm bar is shown in each right lower corner. (C) Temporal sequence of an iMK-derived platelet spreading onto a fibrinogen-coated glass coverslip after activation. Pictures were taken with a 63× oil objective. A 5 μm bar is shown in each bottom right corner.