Fig. 6.

OCT-based particle tracking velocimetry of recirculatory/vortical cilia-driven fluid flow. Note that the same embryo was imaged in Figs. 6 and 7 and only the image well water volume differs between the two image acquisition sessions. (a) shows the particle pathline image. (b) shows the two-dimensional, two-component (i.e. v = v_xi + v_zk) flow velocity field superimposed on the particle pathline image. The arrow direction encodes vector direction, while the arrow color encodes vector magnitude. The recirculatory/vortical whorl noted with a blue arrow in (a) has a faster fluid flow closer to the body than further away. Near the surface of the embryo, the flow is largely anterior-to-posterior (i.e. head-to-tail), while “return” flow current is in a posterior-to-anterior direction. b, body; e, eye; h, head; ps, polystyrene microsphere; t, tail; w, air/water interface. A, anterior; P, posterior.