Fig. 6.

Quantification of cilia-driven flow in mouse trachea. (a) Maximum intensity projection of flow in tracheal lumen showing tail-head flow directed along the bottom and top surface, and recirculatory flow in the center of the trachea due to closed outflow. Overlay of vector flow field estimated with PSV-OCT showing in-plane velocity (v_x,v_z) and direction indicated by length and direction of arrow, and out-of-plane speed |v_y| indicated by size and color of circle placed at base of each arrow. Axes: h- head; t- tail; d- dorsal; v- ventral. (b,c) Quantification of relative values of out-of-plane flow |v_y| versus in-plane flow (v_x² + v_z²)^1/2. In two regions of interest (ROI), one near the surface of the tracheal wall (ROI 1, red) and one in the center of the lumen (ROI 2, green). (c) Histogram of ratio of values of |v_y|/(v_x² + v_z²)^1/2 . Note the logarithmic scale. Values less than one indicate flows that are primarily in-plane, while values greater than 1 indicate flows that are primarily out-of-plane.