Shear field around adherent leukocytes as measured by Micro-PTV

Polystyrene micro-particle (bead) tracking velocimetry (mu-PTV) with automatic object detection was used to measure fluid shear rates around adhered leukocytes in venules of the living murine cremaster muscle. Morphology-based automated bead detection was followed by auction-based bead-pair assignment. Beads above or below the objective's depth-of- field were identified and eliminated by a blurriness algorithm which approximated the microscope's point-spread-function as an axially-varying two-dimensional Gaussian. These data allow construction of shear rate and shear stress maps around adherent leukocytes with 0.5 micrometer resolution.