EPHB2 mutation affects platelet morphology. Illustration of the typical platelet ultrastructure for control (top), P1 (A-C), and P2 (D-G) by transmission electron microscopy. (A-B) Elongated platelets P1 with increased maximal diameter and a discoid shape containing few granules; note the abnormal presence of membrane complexes (MC). (A) Asterisk denotes examples of platelets with a sickle shape and extensions of the plasma membrane suggesting a defect of fragmentation. (C) What appears to be a fragment of a megakaryocyte (MK) with the aspect of an unfragmented proplatelet is shown. (D-G) Platelets from P2. (D) Discoid platelets with numerous membrane complexes. (E) An apparent preplatelet with a barbell-shaped appearance. (F) A lower-magnification image shows the heterogeneity in platelet shape; some are discoid and thin while others are round. (G) An unfragmented MK. Scale bars indicate the magnification.