Characterization of platelets from APP-KO mice. In all the graphs, red bars refer to WT mice, and blue bars refer to APP-KO mice. Data are expressed as mean ± SEM and have been obtained from 3 different experiments, unless otherwise specified. (A) Analysis of APP and tubulin (as control) expression in platelets from WT and APP-KO mice by immunoblotting with specific antibodies, as indicated. (B) Analysis of glycoprotein expression by flow cytometry. (C) Platelets and white blood cells count in whole blood. *P < .05. (D) Blood was withdrawn from WT and APP-KO mice at the indicated points after injection of AlexaFluor488-labeled antibodies to GPIX, and the fraction of labeled to unlabeled platelets was determined (n = 5). (E) Electron microscopy analysis of platelet morphology. (i) Representative images at different magnitude (5600×, upper; and 28 000×, lower). Quantification of the mean platelet diameter and number of internal α and dense (δ) granules is reported in (ii) and (iii), respectively. Data have been obtained from the analysis of 50 different platelets from 5 different slides. *P < .05. (F) Analysis of megakaryocytes and proplatelets formation. (i) Representative images of proplatelets forming megakaryocytes from WT and APP-KO mice on staining with anti-tubulin antibody (green) and with Hoechst (blue). Quantification of total megakaryocytes (MKs) and percentage of cells protruding proplatelets (PP) is reported in (ii) and (iii), respectively. ***P < .005.