Visualization of patent channels formed in clots by RBC-PAs under flow. Z-projections of 3 successive low-magnification images are stitched together with the direction of flow from bottom to top. (A) Just after the start of 160 s⁻¹ shear (16 minutes), fibers and incorporated RBC-PAs are visible (both green), along with a few pores. (B) At 24 minutes, channels have begun to form from pores enlarging in the direction of flow. Some buffer-derived bystander RBCs (red) have entered clots and become trapped in the network. Fibers that have partially lysed tend to align in the direction of flow. (C) At 37 minutes, clearly visible patent channels have formed, and the strands of network that remain are aligned. Some RBC-PAs and buffer-derived RBCs are trapped in the remaining fibrin; the majority of the bystander RBCs traverse clots via channels, and many flow through the sample moving too fast to be captured in these Z-projections but can be detected in the videos (supplemental Data).