Inhibition of clot contraction-mediated extrusion of mouse sickle RBCs from whole blood clots formed ex vivo. (A) Number of RBCs released from clots formed ex vivo from the blood of AA (n = 15), AS (n = 10), and SS (n = 16) mice in the absence (−) or presence (+) of FXIIIa inhibitor T101 (20 µM). ***P < .001. (B) Representative images of whole blood (before initiation of clot formation) and serum (after removal of clots formed for 2 hours). Yellow color of SS serum indicates sparse RBC presence. (C) Effect of changes in hematocrit on the serum RBC content 2 hours after contraction of the clot formed from the blood of AA (n = 9) and SS (n = 11) mice. (D) Scanning electron micrographs of ex vivo whole blood clots. Arrows indicate fibrin, arrowheads indicate sickled RBC processes. Original magnification: ×10 000 (upper) and ×40 000 (lower). (E) Transmission electron micrographs of clots formed ex vivo from the blood of AA and SS mice. Original magnification ×10 000. Gen, genotype.