RBC extrusion during whole blood clot contraction. (A) Citrated whole blood was obtained from male or female AA (n = 11) and AS (n = 11) mice and was preincubated under hypoxic conditions (20 mm Hg for 4 hours) “before” the addition of tissue factor and calcium as described in “Methods.” The sample was incubated for a further 1 hour to allow clotting and retraction, “after” which RBCs extruded into the serum were enumerated. (B) Number of RBCs extruded into the serum during clot contraction. (C) Clot weights in AA and AS mice. ∗∗P < .01; ∗∗∗P < .001.