Defective DMS polarization of ADAP-deficient MKs in vitro. (A-B) Transmission electron micrographs from intact BM of control and ADAP-deficient mice. Scale bars represent 5 µm (top panel) and 2 µm (bottom panel, inset). (B) Release of (pro)platelet-like particles into the BM compartment (BM) next to a sinusoid (S) (top panel). Higher magnification of released (pro)platelet-like particles (arrowheads; bottom panel). (C) Representative confocal images of Adap^+/+ MKs cultured in vitro for 5 days and stained for F-actin (red), GPIX (green), and the nucleus (blue). According to the localization of GPIX and F-actin as well as the position of the nucleus 3 classes were defined (class I-III). Scale bar represents 10 µm. (D) Quantitative analysis of the distribution of the 3 MK classes in vitro on day 5 of cultivation. Five hundred MKs per genotype were analyzed. Values are mean ± SD (n = 5) (**P < .01; *P < .05).