Figure 3.

Platelets are distributed in the thrombus according to their activation state. (A) Representative image of the segmented 10% platelets within a thrombus following a laser-induced injury in serial block-face scanning electron microscopy (left panel) (n = 3). The site of laser injury is indicated by an asterisk. Scale bar: 10 μm. Right panel: enlargement revealing 3 subpopulations of platelets differentially activated: resting platelets (solid arrows), partially activated (dashed arrows), and fully activated (dotted arrows). (B) Enlargements of the representative serial block-face scanning electron microscopy image of the 3 subpopulations of platelets composing the thrombus. Three examples for each sub-population are shown schematically. Scale bar: 1 μm. (C) Quantitative analysis of sphericity values of segmented platelets in the thrombus after a laser-induced injury. Each point corresponds to one sphericity value and, therefore, to an individual platelet, resting platelets (blue), partially activated (purple), and fully activated (red). One hundred platelets have been analyzed. The mean ± SEM is shown. Significance was determined using one-way analysis of variance with Tukey’s multiple comparisons test. (D) Representative image of a thrombus following a laser-induced injury in serial block-face scanning electron microscopy revealing the 3 parts studied: injury, intermediate, and periphery. Scale bar: 10 μm. (E) Quantitative analysis of the distribution of platelets according to their state of activation. One thousand platelets were segmented and over a hundred platelets have been analyzed using the Amira software (Thermo Fisher Scientific).