Chemotaxis in collagen gels.

aMeandering index is defined as net displacement divided by track length, such that migration in a straight line gives a value of 1, while greater meandering leads to values closer to zero. bAngle measures migration along the Y-axis (parallel to the chemokine gradient). Values range from 0° to 180°, such that direct migration toward the chemokine gives a value of 180°. cBearing measures migration along the X-axis (perpendicular to the chemokine gradient). Values range from 90°–270°, such that perfect migration toward the chemokine (no side-to-side wandering), gives a value of 180°.